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Tuberculosis in the Workplace 7 Regulation and the Future of Tuberculosis in the Workplace Of the three questions considered by the Institute of Medicine, the most difficult was: what will be the likely effects on tuberculosis infection, disease, or mortality of an anticipated Occupational Safety and Health Administration (OSHA) standard to protect workers from occupational exposure to tuberculosis? The committee quickly realized—on the basis of conversations with OSHA staff and others—that the final standard on occupational tuberculosis would likely differ from the proposed rule in some important respects. The committee could not, however, be certain of the specific ways in which the proposed rule and the final standard would differ or when the standard would be published. Therefore, rather than concentrate narrowly on individual features of the proposed rule, the committee decided to consider more generally the potential for a final standard to affect the transmission of tuberculosis. Possible effects include both benefits (e.g., cases of active tuberculosis prevented) and harms (e.g., unnecessary treatment following a false-positive tuberculin skin test result). The committee’s charge and the time and resources given to it did not provide for an assessment of the costs or cost-effectiveness of implementing an OSHA standard or for an evaluation of policy options and recommendations. During its 6 months of study and deliberation, the committee considered both positive and negative assessments of the need for OSHA regulations on occupational tuberculosis. On one side is the view that regulation is necessary to (1) achieve more complete, consistent, and long-term compliance with recommended tuberculosis control measures, especially in nonhospital settings, (2) prevent the kind of complacency about tuber-
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Tuberculosis in the Workplace culosis that characterized public health and workplace programs in the 1980s, and (3) extend additional financial and other protections to workers not provided for by voluntary tuberculosis control guidelines. On the other side is the view that (1) the rate of compliance with the tuberculosis control measures recommended by the Centers for Disease Control and Prevention (CDC) is already high; (2) even with the less than full compliance, the measures implemented have been effective; and (3) an OSHA standard would be inflexible, unnecessarily burdensome, and not easily changed to reflect revisions that might result from CDC’s recently initiated review of its 1994 guidelines for health care facilities. The next section of this chapter examines the context in which an OSHA standard would be implemented and the conditions that would need to be met for the standard to have positive effects on tuberculosis infection, disease, or mortality. The section also reviews OSHA’s projections of the number of workplace cases of tuberculosis infection, disease, and mortality that would be prevented if the 1997 proposed rule were implemented. The final section of the chapter considers the relationship between workplace and community tuberculosis control programs. As in previous chapters, most of the available information concerns hospitals. POTENTIAL EFFECTS OF AN OSHA STANDARD ON OCCUPATIONAL TUBERCULOSIS Changing Environment Any assessment of the potential effects of an OSHA standard must recognize the changes in communities and workplaces since OSHA announced its rule-making process in 1994. Even though only 3 years have passed since the proposed rule was issued in 1997, much of the analysis for the rule was developed earlier and relied on 1994 or older data. The epidemiology of tuberculosis has changed substantially in recent years. In addition, health care and correctional facilities appear to have more fully adopted the kinds of tuberculosis control measures described by CDC and OSHA. As described earlier in this report, declining tuberculosis case rates have now been confirmed for the United States for 7 straight years. After increasing by 13 percent between 1985 and 1992, tuberculosis cases rates declined by 35 percent between 1993 and 1999. The rates of multidrug-resistant tuberculosis have also decreased significantly in recent years, from 3.5 percent in 1991 to 1.2 percent in 1999. (Resistance to isoniazid dropped from 8.4 in 1993 to 7.2 in 1999.) These improvements can be attributed at least in part to better funding of community tuberculosis control programs, increased attention to AIDS patients and other groups
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Tuberculosis in the Workplace at increased risk, wider adoption of directly observed therapy, declining rates of human immunodeficiency virus (HIV) infection or AIDS, and improved implementation of tuberculosis control measures in hospitals, prisons, and, perhaps, other congregate settings. Despite progress in efforts to control and prevent tuberculosis in the community, a few big cities still count hundreds of cases each year and occasional workplace outbreaks of the disease continue to be documented. In 1997, only two percent of the U.S. population lived in counties that might be described as “tuberculosis free,” meaning that they had had no cases of tuberculosis in 5 years (Geiter, 1999; see also note in Chapter 6). Continued community and workplace efforts to prevent and control tuberculosis should help enlarge this percentage. Conversely, neglect of tuberculosis control measures could help create the conditions for a new, potentially more dangerous resurgence of the disease. Conditions for an Effective OSHA Standard Given the limited information and time available to the committee as well as the uncertainty about the actual content of a final standard, the committee concluded that it could not reasonably develop any quantitative estimate of the likely health effects of an OSHA standard. Instead, it identified three assumptions or conditions that would have to be met for an OSHA standard to have positive effects on tuberculosis infection, disease, and mortality. Condition 1. Implementation of workplace tuberculosis control measures as recommended by CDC and proposed by OSHA must contribute meaningfully to prevention of the transmission of Mycobacterium tuberculosis in hospitals and other covered workplaces. Condition 2. An OSHA standard must sustain or increase the level of adherence to workplace tuberculosis control measures, especially in high-risk institutions and communities. Condition 3. An OSHA standard must allow reasonable flexibility to adapt tuberculosis control measures to fit differences in the level of risk facing workers. Condition 1. Does implementation of tuberculosis control measures as recommended by CDC and proposed by OSHA help prevent transmission of M. tuberculosis in hospitals and other covered workplaces? Overall, the committee finds that recommended tuberculosis control measures are effective. In Chapter 6, the committee concluded that more attentive implementation of these measures contributed to the ending of outbreaks of tuberculosis in hospitals and to the prevention of new outbreaks.
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Tuberculosis in the Workplace The most important measures appear to be administrative controls, in particular, policies and procedures aimed at promptly identifying, isolating, and treating people with infectious tuberculosis. In addition to the CDC guidelines, hospitals may have been influenced by OSHA’s efforts to enforce the adoption of tuberculosis control measures under the agency’s general-duty clause and its respiratory protection standard. Likewise, after 1997, the expectation that a permanent OSHA standard would be issued may have played a role. Some state regulatory agencies and private accrediting organizations were also enforcing infection control requirements during the 1990s. Because most of the information located by the committee dealt with hospitals, the committee could not reach conclusions about the effectiveness of tuberculosis control measures in these workplaces. To various degrees, these workplaces differ from hospitals and each other in physical environments, resources available, populations served, and range of tasks undertaken by different categories of workers. These workplaces may also differ in the level of management and worker understanding and acceptance of the threat of tuberculosis and the need for control measures. In principle, however, basic control measures such as screening to promptly identify and isolate those with symptoms and signs of tuberculosis should help prevent transmission of M. tuberculosis in prisons and other congregate settings serving populations at increased risk of tuberculosis. Tuberculosis control measures cannot be expected to prevent all worker exposure to the disease. In areas with moderate to high levels of tuberculosis, occasional worker exposure to patients with infectious tuberculosis can be expected. For example, opportunities for exposure will exist in emergency departments and other “intake” areas before infectious individuals are recognized and isolation protocols can be applied and completed. Furthermore, not all individuals with infectious tuberculosis have easily recognized symptoms or signs of the disease, so workers may be exposed to them for some time before tuberculosis is suspected and diagnosed. Conscientious implementation of tuberculosis control measures does not guarantee that transmission will never occur, but it appears to reduce risk significantly, especially in high-prevalence areas. Condition 2. Will an OSHA standard help sustain or increase the level of adherence to effective workplace tuberculosis control measures? As the past decade’s outbreaks of tuberculosis recede in memory and cost control continues as a priority for community and occupational health programs, the potential once again exists for communities and workplaces to neglect the control measures that helped end workplace outbreaks and reverse increases in tuberculosis case rates. The information
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Tuberculosis in the Workplace reviewed in Chapters 5 and 6 suggests that the 1982 and 1990 CDC guidelines were not widely implemented and that lapses in infection control likely contributed to the workplace outbreaks of tuberculosis reported in the late 1980s and early 1990s. The 1994 CDC guidelines appear to be more widely accepted and adopted, albeit with some gaps between formal policies and day-to-day practices. Except to the extent that they have been incorporated as requirements by other public or private agencies, the steps recommended by CDC are voluntary. On the basis of logic and experience, the committee expects that an OSHA standard would sustain or increase the rate of compliance with mandated tuberculosis control measures. First, a national standard is likely to motivate more organizational adherence to tuberculosis control measures than can be achieved by voluntary guidelines, variable state laws, or the threat of bad publicity or litigation in the event of a tuberculosis outbreak. The committee believes that most organizations want to do right as defined by laws, guidelines, ethical principles, and lessons of science or experience. It also believes that compliance with recommended practices can usually be increased by the threat of citation and financial penalties that lies behind regulations. Second, as argued by OSHA, the committee agrees that a standard will be clearer, more hazard specific, and easier to enforce than either the general-duty clause in OSHA’s statute or OSHA’s existing standards on respiratory protection. Unlike OSHA’s general-duty clause, a standard allows the agency to identify and require actions to abate workplace risks in advance. Unlike OSHA’s general standard on respiratory protections, a tuberculosis standard would, in certain respects, be specific to this biologic hazard (e.g., by describing types of hazardous situations—such as entering an isolation room—and identifying respirators or respirator characteristics appropriate to these situations). Third, by providing a firmer basis for OSHA enforcement actions, a standard should also put workers on stronger ground in identifying and challenging an employer’s inadequate implementation of the tuberculosis control measures specified by the standard. Such a challenge need not involve an actual complaint to OSHA. Notifying an employer of deficiencies may be sufficient to prompt corrective action. One caveat needs to be mentioned, however. State and local government hospitals and other facilities would not be covered by an OSHA standard unless a state had an approved OSHA plan for enforcing the standard in these facilities. The facilities might, however, be subject to other infection control requirements, for example, those set forth in state licensure laws. Also, if a facility such as a state or local correctional used a private contractor to run the facility’s medical department, that private contractor would be covered by the standard for its activities and employees.
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Tuberculosis in the Workplace Condition 3. Will an OSHA standard allow reasonable adaptation of control measures to fit different organizational situations or changing environmental circumstances? In general, regulations tend to reduce organizational flexibility. Revisions in regulations may also lag behind important changes in the environment or in the problem that gave rise to the regulation in the first place. Although much of the controversy about the flexibility of an OSHA tuberculosis standard focuses on costs or cost-effectiveness, some criticisms—mainly those relating to tuberculin skin testing requirements— involve the potential for inflexible requirements to harm workers’ health. (As discussed earlier and below, CDC is reexamining its recommendations on tuberculosis control in health care facilities, including its statements about baseline and periodic tuberculin skin testing.) The voluntary character of the CDC guidelines ultimately gives employers at any risk level the discretion to tailor their responses to the particular risks faced by their workers. Although some provisions of the 1994 guidelines are described as requirements, CDC has no enforcement power. Also, many statements are not phrased as “shoulds” (much less “musts”) but, rather, are presented as suggestions for organizations to consider. The following discussion compares the flexibility offered by the 1994 CDC guidelines and the 1997 proposed OSHA rule in three areas. The first and most important area involves the provisions of each for assessing the workplace risk of tuberculosis transmission, categorizing workplaces by the level of risk facing workers, and matching tuberculosis control measures to the level of risk. The other two areas involve tuberculin skin testing programs and respiratory protection programs. Matching Requirements to Risk Level: Facility Risk Assessment Chapters 1 and 5 make clear that the incidence of tuberculosis varies substantially among communities and that the risk of acquiring infection with M. tuberculosis has varied among hospitals and other workplaces. As described in Chapter 4, the 1997 proposed OSHA rule provides some very limited risk-related flexibility by distinguishing two categories of organizations, one of which would face fewer regulatory requirements. To quality for the “lower risk” category (a label not used in the proposed rule), an organization would have to (1) neither admit nor provide medical services to individuals with suspected or confirmed tuberculosis, (2) have had no confirmed cases of infectious tuberculosis during the previous 12 months, and (3) be located in counties that have had no confirmed cases of infectious tuberculosis during 1 of the previous 2 years and fewer than six cases during the other year. Any facility that did not meet all of these
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Tuberculosis in the Workplace criteria would have to meet all of the proposed rule’s requirements applicable to its type of work environment. In contrast, the 1994 CDC guidelines provide for a more complex risk assessment process for health care facilities. That process incorporates more information and differentiates facility risk level and related control measures more finely.1 The guidelines specify that a health care facility or an area within a facility may be assigned to one of five risk categories: minimal, very low, low, intermediate, and high. For the facilities in the two lowest risk categories, the guidelines recommend considerably fewer control measures.2 Even if a facility had admitted no tuberculosis patients, had no tuberculosis cases in its community, and had a policy of referring those with diagnosed or suspected tuberculosis, that facility could not qualify for OSHA’s “low risk” category if the surrounding county had reported one case of tuberculosis in each of the preceding 2 years. As discussed in Chapter 4, a facility’s service area may not match county boundaries and may have a much different incidence of tuberculosis. Reasonable flexibility in adoption of tuberculosis control measures does not imply lack of attention to the risk of tuberculosis in low risk facilities. Both the CDC guidelines and the proposed OSHA rule specify that all facilities—even those that have not recently encountered someone with active tuberculosis—should have protocols and trained individuals in place to identify the unexpected infectious individual and then transfer or otherwise manage the person in ways that minimize risks to workers and others. The issue is the degree to which control measures can be matched to tuberculosis risk in the community and in the facility, taking into account the facility’s experience in preventing transmission of tuberculosis. The risk assessment criteria described in the CDC guidelines allow for a more sensitive match between control measures and tuberculosis risk than do the criteria in the proposed OSHA rule. Overall, the committee concludes that if an OSHA standard follows the 1997 proposed rule it may not offer sufficient flexibility for organizations to adopt control measures appropriate for the level of risk facing workers. To the extent that an OSHA standard inflexibly extends requirements to institu 1 As described in Chapter 4, the CDC risk assessment process includes a review of the community tuberculosis profile, the numbers of patients with tuberculosis examined or treated in different areas of the facility, the tuberculin skin test conversion rates for workers in different areas of the facility or in different job categories, and evidence of person-to-person transmission of M. tuberculosis resulting in active disease. The process also includes review of medical records to identify possible delays or deficiencies in identifying or treating individuals with infectious tuberculosis. In some cases, it calls for observation of infection control practices. 2 For the three higher-risk categories, the CDC recommendations differ primarily in whether they call for certain steps to be taken yearly or more frequently.
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Tuberculosis in the Workplace tions that are at negligible risk of occupational transmission of M. tuberculosis, the standard is unlikely to benefit workers at the same time that it would impose significant costs and administrative burdens on covered organizations and absorb institutional resources that could be applied to other, potentially more beneficial uses. Requirements for Baseline and Serial Tuberculin Skin Testing In addition to the broad concerns about whether an OSHA standard would allow sufficient flexibility for organizations to match tuberculosis control measures to the risk facing workers, a narrower question is whether a standard would allow organizations reasonable flexibility to adjust tuberculin skin testing programs to reflect the changing epidemiology of tuberculosis and, possibly, changing CDC recommendations. As described in Chapter 2 and Appendix B, when the prior probability of tuberculosis infection is low because of low prevalence, Bayes’ Theorem shows that the probability of false positive test results increases. When prevalence decreases to very low levels, the majority of those with positive tests will not in fact be infected. This, in turn, increases the potential for workers to be treated unnecessarily for latent tuberculosis infection. The most serious possible harm of unnecessary treatment involve a very small risk of liver damage, although this risk is lower than previously thought (Nolan et al., 1999, as discussed in Chapter 2). Less serious potential harms include rashes, gastrointestinal upsets, fever, and joint pain. In addition, some people may suffer needless anxiety or fear related to a false-positive test result or subsequent treatment. Furthermore, the less an individual’s social contacts understand about the meaning of a positive test result, the greater the potential for a person’s social relationships to be compromised by such a result. Excessive workplace testing and treatment efforts would also waste resources that could be constructively used to support other aspects of a workplace tuberculosis control program. That the tuberculin skin test has some limitations, especially in low-prevalence environments, does not mean that it is a poor test. It has been a valuable element in tuberculosis control programs, including in outbreak situations and as part of surveillance programs in health care and other facilities in high prevalence areas. Nonetheless, as recommended by the IOM report Ending Neglect: The Elimination of Tuberculosis in the United States (IOM, 2000), better diagnostic tests for both infection and active disease are needed. Recognizing that the circumstances that prompted the 1994 guidelines have changed, the CDC’s Advisory Council for the Elimination of Tuberculosis recently recommended that CDC review and, if appropriate, revise the guidelines, including the recommendations for tuberculin skin testing. Such a review is now under way, and the committee under-
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Tuberculosis in the Workplace stands that new recommendations may be published sometime in 2002. OSHA could adapt its requirements for tuberculin skin testing to changes in CDC recommendations, for example, by declaring departures from the testing requirements in the standard to be de minimus violations (i.e., unimportant and not subject to citation or penalty). More straightforward, the standard could be revised to state that OSHA requirements for skin testing would follow CDC recommendations. Requirements for Respiratory Protection Program Much of the concern about the 1997 proposed OSHA rule has focused on the requirements for personal respiratory protection. When the CDC guidelines were published in 1994, they, too, were criticized for their recommendations for respiratory protection. Some of the criticism involved the cost and complexity of the limited choice of personal respirators that met the criteria set forth by the CDC in 1994. Much of that criticism abated soon thereafter when the National Institute for Occupational Safety and Health approved the relatively inexpensive and simple N95 respirators. Earlier sections of this report describe personal respiratory protections as the third element in CDC’s hierarchy of tuberculosis control measures. As discussed in Chapter 6, outbreak studies support this hierarchy and suggest that most of the benefit of control measures comes from administrative and engineering controls. Modeling exercises support the tailoring of personal respiratory protections to the level of risk faced by workers—that is, more stringent protection for those in high-risk situations and less stringent measures for others. The following discussion considers first the workers targeted for respirator use by the 1994 CDC guidelines and the 1997 proposed OSHA rule. It then examines the requirements for fit testing of personal respirators. Requirements for Respirator Use Although the respiratory protection requirements of the 1997 proposed OSHA rule have been criticized for inflexibility, the proposed rule and the 1994 CDC guidelines mostly target the same types of workers for use of personal respirators. The wording differs, but both essentially call for workers to be provided personal respirators if they (1) enter isolation rooms housing people with known or suspected infectious tuberculosis, (2) are present when certain high-hazard procedures such as bronchoscopies are performed on individuals with known or suspected tuberculosis,3 (3) transport such indi- 3 The CDC guidelines (but not the proposed OSHA rule) also mention that workers performing such procedures might sometimes need more protective respirators (e.g., powered air-purifying respirators).
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Tuberculosis in the Workplace victuals, whether masked or not, in enclosed vehicles, or (4) otherwise work in areas where they may be exposed to contaminated air.4 The 1994 CDC guidelines are ambiguous for one low-risk situation involving facilities that are located in communities with tuberculosis, that have a policy of referring tuberculosis patients, and that have not admitted a tuberculosis patient within the preceding year. Workers in such facilities may be exposed to infectious tuberculosis while evaluating a patient in an emergency department or other area. The guidelines advise that these workers “may” need to be included in a respiratory protection program. The 1997 proposed OSHA rule appears to require explicitly that employers provide respirators to such workers if a patient is being evaluated because tuberculosis is suspected. Although the proposed OSHA rule seems to require the use of personal respirators for workers in a few situations that are not clearly covered by the CDC guidelines, the committee could not determine how many additional employers or employees might be affected. In general, both the proposed rule and the guidelines focus their respirator use provisions on the worker’s reasonably anticipated risk of exposure rather than the facility’s risk category. Requirements for Fit Testing As described in Chapter 4, both the 1994 CDC guidelines and the 1997 proposed OSHA rule provide for initial training and fit testing for workers who use personal respirators. Consistent with the then-applicable 1987 OSHA respiratory protection standard, the 1994 guidelines do not mention annual fit testing. Consistent with the 1998 respiratory protection standard (see Chapter 4), the 1997 proposed OSHA rule provides for an overall respiratory protection program that includes both initital and annual fit testing. In general, it seems rather a common-sense proposition that any workers who are provided with new safety equipment (such as a personal respiratory device) should also be provided some initial training in the equipment’s proper use and maintenance and some continuing education to remind them about when and how it is to be used. Likewise, if the equipment differs by size, shape, or other characteristics to accommodate individual physical differences, then some kind of initial fit evaluation also seems generally plausible. Administratively, a program for fit of testing personal respirators requires trained personnel to conduct a complicated series of tests. New 4 The CDC guidelines do not specifically mention workers repairing air systems likely to contain airborne M. tuberculosis. Such workers would, however, seem to be covered under the guideline’s more general language specifying the use of personal respirators by workers in “other settings where administrative and engineering controls are not likely to protect them from inhaling infection airborne droplet nuclei” (CDC, 1994b, p. 97).
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Tuberculosis in the Workplace equipment reduces the time required to administer the test, but the equipment is expensive and not yet in general use. Scheduling for an annual fit test must allow time for the test as well as time for workers to get to and from the test site (which may be on another floor or in another building). If a worker misses the test, he or she must be rescheduled. If the test itself cannot be provided when scheduled, new times must be scheduled for multiple workers. A requirement for annual retesting multiplies the number of people who must be scheduled and tested each year. The more workers who are covered by an employer’s respiratory protection program, the more complex will be the employer’s administrative burden and the greater the expense. For large medical centers that treat substantial numbers of tuberculosis patients, annual fit testing can be a major undertaking that involves thousands of workers. Employers now have two fit testing options. In a qualitative fit test, the respirator user reports whether he or she can detect an external aerosol. For example, if the test substance is a saccharin aerosol, users can detect a sweet taste if the respirator does not fit properly (e.g., because of leakage at the face seal surface). In a quantitative fit test, the concentration of a marker material inside and outside the mask is determined by relatively complex equipment that produces more accurate results. In a recently reported laboratory test, McKay and Davies (2000) compared two substances, Bitrex and saccharin, which are commonly used in qualitative fit testing. The researchers found that all 26 test subjects accurately detected leaks in respirators when exposed to Bitrex but that one-third did not identify leaks when saccharin was used. A second study by the same researchers (reported so far only in an abstract), now appears to cast doubt on the use of Bitrex as a fit-testing agent in certain situations (McKay, 2000). Coffey and colleagues (1999) quantitatively tested the performance of N95 respirators in a simulated workplace setting. They made direct measurements of ambient particles both outside and inside the masks of 25 subjects who wore different types of commercially available respirators. The investigators report considerable model-to-model variability in the degree of protection against filter penetration by the test particles. Additionally, when testers applied the 1 percent pass-fail criterion required by OSHA, a substantial majority of test subjects failed the fit test for 17 of the 21 devices tested, that is, most subjects could not be successfully fitted. (The 1 percent pass-fail criterion is thought to be needed to achieve no more than 10 percent respirator face-seal leakage during normal use in the work place.) A determination that qualitative fit testing is ineffective and that quantitative fit testing is required could add substantial costs to a respiratory protection program, especially one that included annual testing for large numbers of workers. The findings by Coffey and colleagues raise a further serious concern that with quantitative fit testing,
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Tuberculosis in the Workplace most workers might not pass a fit test with the currently available models of the widely used N95 respirator. This suggests that more attention should perhaps be paid to mask performance at the manufacturing and premarketing stage. A determination that qualitative fit testing is ineffective and that quantitative fit testing is required could add substantial costs to a respiratory protection program, especially one that included annual testing for large numbers of workers. The findings by Coffey and colleagues raise a further serious concern that with quantitative fit testing, most workers might not pass a fit test with the widely used N95 respirator. The committee found no epidemiologic studies that have evaluated whether qualitative or quantitative fit testing (either initial or annual) for N95 or other respirators used for tuberculosis control improves respirator fit in normal practice as workers treat, transport, guard, or otherwise have contact with people who have known or suspected tuberculosis. Given the relatively small numbers of workers with skin test conversions, it is unlikely that field studies would be sensitive enough to demonstrate whether initial or annual fit testing reduced worker’s occupational risk of acquiring tuberculosis infection or active tuberculosis. The committee located no modeling studies that focused specifically on the potential health effects of fit testing. One small, single-site study has suggested that education about proper fit may be as effective as physical fit testing (Hannum et al., 1996). In that study, a hospital recruited workers to participate in one of three respirator training programs. Researchers then tested the workers on their ability to correctly adjust their respirator’s fit and seal. They concluded that training was important but that it did not matter much whether the training included direct fit testing or a classroom demonstration of how workers should fit check their respirator before each use. The devices used in the study were high-efficiency particulate air (HEPA) respirators, which differ from the now widely used N95 respirators. Thus, this study is not directly relevant to N95 respirators. Flexibility of Respiratory Protection Requirements Perhaps paradoxically the committee’s most daunting challenge was to assess whether the 1997 proposed OSHA rule allowed employers reasonable flexibility to match respiratory protections to the level of risk. Although the group agreed that respiratory protection is the least important of the hierarchy of tuberculosis controls, it also agreed that respirators and respiratory protection programs have a role to play when an occupational risk of tuberculosis exists. As described in Chapter 6, modeling studies suggest that the benefits of respiratory protection are directly proportional to the presence of risk. In facilities that admit only the occasional individual with tuberculosis or
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Tuberculosis in the Workplace that have a policy of transferring such individuals, workers are likely to see no or very marginal additional protection from an extensive respiratory protection program. In a high-risk setting with many tuberculosis admissions, questionable administrative and engineering controls question, and, especially, cases of multidrug-resistant disease, a rigorous respiratory protection program may be beneficial. The 1997 proposed OSHA rule allows little flexibility for organizations to adopt respiratory protection programs that reflect the variability in the level of risk facing workers. For low-risk institutions, a proportionately modest program might include the availability of N95 respirators and the training of key individuals in their appropriate use. In high-risk facilities, a program might include a spectrum of respiratory protection devices including N95 respirators for most situations and a more protective respirator for selected high-hazard procedures such as bronchoscopy and autopsy. The education and fit-testing elements of a respiratory protection program would then be tailored to the risk facing different employees. In both high- and low-risk institutions, the highest priority would still be administrative controls that promote prompt identification and isolation of those with signs and symptoms suspicious for tuberculosis. For institutions that may admit those with tuberculosis, engineering controls are also important. Given the variability of masks from different manufacturers that was noted earlier, it may be appropriate for policymakers to focus more attention on manufacturers so that generally poor-fitting respirator models are not marketed. In addition, further research and analysis may be useful to examine fit-testing criteria and methods in laboratory versus operational settings and to determine levels of respiratory protection that will reasonably reduce risk in environments posing different degrees of risk to workers. Summary: Conditions for an Effective OSHA Standard Overall, the committee concludes that an OSHA tuberculosis standard can have a positive effect if it meets three basic conditions: (1) it is consistent with tuberculosis control measures that appear to be effective, (2) it sustains or increases the level of compliance with those measures, and (3) it allows employers appropriate flexibility to adopt control measures that are matched to the level of risk facing their workers. The committee expects that a standard will meet the first two conditions by sustaining or increasing the rate of use of tuberculosis control measures that appear to be effective. The committee is, however, concerned that if an OSHA standard follows the 1997 proposed rule, it will not meet the third condition of allowing organizations reasonable flexibility to adopt measures appropriate to the level of risk facing their workers.
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Tuberculosis in the Workplace OSHA’s Projections of Averted Infections, Disease, and Mortality from Implementing a Standard on Occupational Tuberculosis As discussed in Chapter 3, courts have directed OSHA to undertake quantitative risk assessments to justify its standards. Such risk assessments are often difficult because relevant data about the full extent of a workplace hazard and the consequences of control measures are very limited. These difficulties are present in full measure for the assessment of the 1997 proposed rule on occupational tuberculosis. In the 1997 proposed rule, OSHA presented a quantitative risk assessment that estimated the number of infections, cases of disease, and deaths due to tuberculosis that would be averted by adoption of the rule. OSHA staff had four experts review an earlier version of the risk assessment, and they made some revisions on the basis of the reviewers’ comments. In preparation for the issuing of a final standard on occupational tuberculosis, OSHA staff have again revised and updated their estimates. This new analysis was not, however, available to the committee pending publication of the final standard. Therefore, the following comments necessarily apply to the earlier analysis included in the 1997 proposed rule. Although OSHA published the proposed rule in 1997, much of the data on which it relied were several years older (e.g., a 1994 Washington State survey, 1991 data from Jackson Memorial Hospital in Miami, and a 1984–1985 North Carolina study). As summarized in this chapter, tuberculosis cases, case rates, and deaths have been declining since 1993, and recent studies also suggest low levels of occupational transmission of M. tuberculosis. The changing epidemiology of tuberculosis reflects both community and workplace tuberculosis control measures. Given this change, it is not surprising that the assessment presented with the 1997 proposed rule is outdated and that OSHA has revised it. (Again, the revised analysis was not available to the committee.) Infection with M. tuberculosis In 1997, OSHA defined infection with M. tuberculosis as the “material impairment of health.” It did so on the basis of both the potential for latent infection to progress to active disease (which is discussed further below) and the risk for adverse health effects from treatment of the infection. As described earlier, although treatment is not risk free and individuals offered treatment should be informed of both benefits and risks, recent data suggest that the risk of liver damage from carefully monitored treatment of latent infection using isoniazid is quite low and is less than that described in the proposed rule. Estimation of levels of tuberculosis infection and potential reductions in such infections as a result of an OSHA standard is particularly
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Tuberculosis in the Workplace difficult in the absence of any recent systematic data on infection levels on a national or state-by-state basis. The last national survey of infection was undertaken in the early 1970s. As discussed in Chapters 5 and 6 and Appendixes C and D, all studies used to estimate the occupational risk of infection and the effects of tuberculosis control measures have their limitations. The committee recognizes OSHA’s efforts to take some criticisms of its estimating strategy into account. For example, after reviewers criticized the use of 1982 and 1984 Washington State data, in part, because the data were more than 10 years old, OSHA staff substituted data from a 1994 survey. Similarly, after data from a 1984–1985 North Carolina survey were criticized as likely being confounded by cross-reactions to atypical mycobacteria in the central and eastern parts of the state, the analysts used only data from hospitals in western North Carolina. The analysts also adjusted the 1984 data to reflect subsequent decreases in active tuberculosis in the state. Nonetheless, the committee concludes that OSHA’s original estimate that the proposed regulations would reduce yearly work-related tuberculosis infections by 90 percent from 1994 levels (thereby averting 21,400 to 25,800 infections) is overstated.5 As discussed above, tuberculosis cases and case rates have declined substantially since 1993. Further, the committee is concerned that OSHA’s analysis did not adequately recognize the contributions to worker infections of (1) unsuspected and undiagnosed cases of active tuberculosis in the workplace or (2) exposure in the community. One concern involves the choice of the definition for internal control and exposed groups for Washington State data (definition 1 as discussed in 62 FR 201 at Table V-3). Another concern is the use of North Carolina data flawed by very low hospital response rates and inconsistent skin testing procedures. The committee also has some concerns about OSHA’s use of 1991 data from Jackson Memorial hospital, which experienced a 1989 to 1990 outbreak of tuberculosis among patients on an HIV ward. Although the data used were for the year after the conclusion of the outbreak, skin test conver- 5 The agency’s state-by-state estimates of the “annual excess risk of tuberculosis infection due to occupational exposure” were defined as “a multiplicative function of the background rate of infection” (62 FR 201 at 54192). The agency then derived its estimates of the background rate of infection on the basis of a mathematical model that assumes that the rate of infection in an area can be “expressed as a numerical function of active tuberculosis cases reported in the same area” (62 FR 201 at 54197). Given the limited time and resources available to it, the committee did not evaluate this mathematical model. In the 1997 proposed rule, OSHA estimates the occupational risk of tuberculosis infection over a 45-year working lifetime to range from 4 to 723 per 1,000 population for hospital workers (with the lowest estimates based on the Washington State data and the highest based on the Jackson Memorial Hospital data).
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Tuberculosis in the Workplace sions among hospital workers exposed on the HIV ward in late 1990 were recorded in early 1991 (Wenger et al. 1995). Also, tuberculosis control measures (e.g., stricter isolation protocols) were still being implemented on the HIV ward in 1991. The committee questions the appropriateness of using outbreak-affected data as a basis for the high-end estimates of the effects of the proposed regulations on occupationally acquired infections. Active Tuberculosis Based on its estimating procedures and assumptions, OSHA concluded that implementation of the proposed rule would prevent each year between 1,477 and 1,744 cases of active tuberculosis among workers covered by the rule (p. 54219, Table VII-3). CDC data raise some questions about the plausibility of these estimates. In its surveillance report for 1999, CDC lists a total of 551 cases of tuberculosis among health care workers and 16 cases among correctional facility workers (CDC, 2000b).6 This figure is less than two-thirds the number of cases that OSHA predicted would be prevented yearly by the implementation of its proposed rule. Moreover, of the reported cases of active disease reported, some proportion will have been the result of community rather than workplace exposure. Although the figure is widely cited and used (including by the CDC), the committee also questions OSHA’s estimate that 10 percent of workers infected with M. tuberculosis would progress to active disease over their lifetimes. Two reviewers of the initial OSHA risk assessment (George Comstock and Bahjat Qaqish) questioned whether this estimate was too high, although a third reviewer (Neil Graham) noted that it was widely accepted (see 62 FR 201 at 54198). In this report’s background paper on the occupational risk of tuberculosis (Appendix C), the author (Thomas M.Daniel) likewise questions the 10 percent figure based on data analyses indicating that the rate of progression is probably half that figure or less, especially in populations more likely than average to be treated for latent infection. Most health care workers constitute such a population, although home health workers, workers in homeless shelters, and certain other groups covered by the proposed rule may have less access to health insurance and health care. The committee recognizes that the rate of compliance with treatment for both latent infection and active disease is often 6 Health care and correctional workers account for about 95 percent of those covered by the proposed rule. The CDC data are based on reported occupation within the past 24 months (CDC, 2000b). Most of the progression from infection to active tuberculosis occurs within the first two years following infection. CDC first began collecting occupational data in 1993, but the initial reports are considered less reliable than subsequent ones. In recent years, approximately 500 to 600 cases of tuberculosis among health care workers have been reported yearly.
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Tuberculosis in the Workplace low, but well-structured programs involving education and directly observed therapy can improve rates of completion of treatment for both conditions (Camins et al., 1996). Recent guidelines from the CDC and the American Thoracic Society strongly recommend treatment for latent infection (ACT/CDC, 2000b). In sum, the committee believes that the 1997 estimates of cases of active tuberculosis that a rule will avert are overstated on three grounds. First, the estimate is inconsistent with reported data on tuberculosis cases by occupation. Second, the rate of progression from infection to active disease is likely lower than traditionally cited. Third, the estimate of infection levels to which the progression rate is applied is too high. One committee member disagreed with this general assessment. That member argued that the validity and reliability of CDC’s own data on tuberculosis case rates by occupation are questionable and that the 10 percent progression figure is reasonable since it continues to be cited by CDC. Tuberculosis Mortality In the 1997 proposed rule, OSHA estimated that the proposed rule would prevent between 115 and 136 tuberculosis-related deaths among covered workers each year. (It also estimated that the rule would also avert 23 to 54 additional deaths among family and other contacts of workers.) The committee concludes that the mortality estimates are overstated. First, as discussed above, the committee believes that the estimates of number of tuberculosis cases that would be averted by a standard are too high. Second, the estimated mortality rate used in the assessment does not take into account demographic factors or the effects of treatment. In the 1997 proposed rule, OSHA estimated that 7.8 percent of all active tuberculosis cases among workers would end in death. It based the estimate on the 3-year average of mortality data reported by CDC for 1989 to 1991 (62 FR 201 at 54207). (More recent CDC surveillance reports apparently include revised numbers for tuberculosis cases and deaths for these years. Based on these numbers, the average case death rate for 1989– 1991 is 7.3 percent.) Case mortality rates reported by CDC for recent years are lower: 6.0 percent in 1998, 5.9 percent in 1997, and 5.6 percent in 1996 (CDC, 2000b). (Population mortality rates dropped from 0.8 per 100,000 population in 1989 to 0.6 in 1994 to 0.4 in 1998.) Thus, use of revised and recent tuberculosis case mortality data would reduce the OSHA estimates. More important, estimates of deaths among health care and other workers should take into account the effects of treatment. The majority of deaths due to tuberculosis occur in individuals in whom the disease is first recognized after death, meaning that their disease was not being treated (Rieder et al., 1991). In addition, the majority of cases of tuberculosis occur among unemployed individuals (CDC, 2000b). Such individuals
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Tuberculosis in the Workplace are likely to have poor access to health care and, thus, to experience serious delays in diagnosis and treatment or to go untreated altogether. Even if all cases of tuberculosis among health care workers were due to occupational acquisition, which is clearly not the case, OSHA’s estimates translate into an unrealistic 20 to 25 percent rate of tuberculosis-related mortality based on the number of cases of disease reported by CDC for health care and correctional workers in recent years. For people with drug-sensitive disease who are diagnosed early and treated fully, the risk of death is very low (Cohn et al., 1990; Combs et al., 1990; Appendix C). Those who have both suppressed immune systems and multidrug-resistant disease, however, run a very high risk of death (Garrett et al., 1999, Appendix C). Fortunately, levels of multidrug-resistant disease are low in the United States and have been declining in recent years. Unlike unemployed individuals, many workers covered by the proposed OSHA rule tend to have good access to health care and to spend their working day among health care professionals. In general, they should be more likely to be diagnosed relatively early and to be offered prompt, appropriate treatment. The financial protections for workers provided for in the 1997 proposed rule also should encourage workers to seek evaluation and treatment if they suspect they have contracted tuberculosis. THE WORKPLACE AND THE COMMUNITY Unlike typical occupational health problems such as those involving hazardous chemicals or dust exposures, the occupational risk of tuberculosis has a close connection to the risk of tuberculosis in the surrounding community. A theme throughout this report has been the interconnection between community risk and workplace risk and the challenge of fitting workplace tuberculosis control measures to these risks and to changes in risks over time. The committee draws a parallel between the circumstances facing occupational health programs and the circumstances described in the recent report Ending Neglect: The Elimination of Tuberculosis in the United States (IOM, 2000). That report attributed the resurgence in tuberculosis in the 1980s to complacency resulting from the striking reduction in disease resulting from effective treatments introduced after World War II. Complacency led to disinterest in the goal of tuberculosis elimination and to the dismantling of tuberculosis control programs. Basic public health measures were neglected, including surveillance activities, contact tracing, outbreak investigations, and case management services to ensure completed treatment of latent infection and active disease. This helped set the stage for the resurgence of tuberculosis in the 1980s when new circumstances emerged—including the HIV and AIDS epidemic, the increase
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Tuberculosis in the Workplace in the rate of multidrug-resistant disease (largely due to incomplete treatment), and expanded immigration from areas with high rates of tuberculosis. For health care facilities, prisons, and other organizations that serve people at high risk of tuberculosis, a similar pattern of workplace neglect in the late 1980s and early 1990s contributed to workplace outbreaks of tuberculosis. Surveys, investigations of outbreaks, and facility inspections all point to institutionalized lapses in tuberculosis control including inattention to signs and symptoms of infectious tuberculosis, delays in initiating appropriate evaluations and treatments, and improper ventilation of isolation rooms and areas. Outbreaks were, however, concentrated in a relatively small number of states that account for a large proportion of people with HIV infection, immigrants from high-prevalence countries, and cases of multidrug-resistant disease. Just as community neglect interacted with workplace neglect to set the stage for workplace outbreaks of tuberculosis, it now appears that community control measures have interacted with workplace control measures to help end outbreaks and reduce the potential for new ones. For example, public health efforts to ensure completed treatment of active tuberculosis can be credited with reducing the number and proportion of people appearing in hospitals and other workplaces with highly lethal, multidrug-resistant disease. This has reduced the risk to workers in these settings. At the same time, the implementation in hospitals of better tuberculosis control measures as recommended by CDC has almost certainly reduced the rates of transmission of drug-sensitive and multidrug-resistant tuberculosis not only within hospitals but also in the broader community into which patients are discharged. The challenge now is to understand and adapt to the decreasing incidence of tuberculosis without re-creating the conditions that will make institutions and workers vulnerable to new and possibly more deadly outbreaks of the disease. Maintaining expertise and vigilance will not be easy assuming that tuberculosis case rates continue to decrease. Ending Neglect set out a strategy for maintaining long-term vigilance and moving toward the elimination of tuberculosis in the United States. (The report’s recommendations are listed in Appendix G.) This strategy stresses (1) better methods for identifying people with recently acquired tuberculosis infection, (2) stronger efforts to effectively treat those who could benefit from treatment of infection, (3) research to develop effective vaccines, (4) more active product development initiatives focused on diagnostic and treatment technologies, and (5) research to tackle the problem of patient and provider failure to follow treatment recommendations. Many of the recommendations from the earlier report would, if implemented, benefit workplace- as well as community-based tuberculosis control programs. One recommendation calls for research to de-
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Tuberculosis in the Workplace velop better diagnostic tests and treatments for latent tuberculosis infection and active tuberculosis, a need identified in Chapter 2.7 Another recommendation is for research on nonadherence to treatment regimens that could be used to develop more effective strategies to promote acceptance and completion of treatment.8 A third recommendation proposes new approaches to identifying and treating latent tuberculosis infection among high-risk immigrants, who are well represented in the health care workforce.9 The report stresses that after treatment of active disease, “the second priority is targeted tuberculin skin testing and treatment of latent infection” (IOM, 2000, p. 8). In addition to immigrants from high-prevalence countries, the high-risk groups targeted include prison inmates, people with HIV infection, and homeless individuals. The report also calls for the United States to increase its support for global tuberculosis control. With more than 40 percent of tuberculosis cases in the United States and among health care workers involving people born in other countries, policymakers and public health authorities cannot ignore the international problem of tuberculosis. In sum, just as tuberculosis risk in the workplace is linked to tuberculosis risk in the community, the risk in American communities is affected by the risk of tuberculosis elsewhere in the world and by migration within and across the nation’s borders. Effective tuberculosis control measures in the workplace are one element of a much larger strategy to prevent and eventually eliminate the disease. 7 Recommendation 5.2. To advance the development of diagnostic tests and new drugs for both latent infection and active disease, action plans should be developed and implemented. CDC should then exploit its expertise in population-based research to evaluate and define the role of promising products (IOM, 2000). 8 Recommendation 5.3. To promote better understanding of patient and provider nonadherence with tuberculosis treatment recommendations and guidelines, a plan for a behavioral and social science research agenda should be developed and implemented (IOM, 2000). 9 Recommendation 4.1 calls for preimmigration tuberculin skin testing of visa applicants from countries with high rates of tuberculosis. Once they have arrived in the United States, those with positive skin tests would, when indicated, be required to complete an approved course of treatment for latent tuberculosis infection before being issued a permanent residency card (“green card”). (Screening and treatment for active tuberculosis are already required.) The report also recommends that the federal government support the cost of such treatment rather than putting the burden on local communities.
Representative terms from entire chapter: