CDC urges OSHA to amend TB testing provision
SHEA: Proposed TB rule lacks credibility
The Occupational Safety and Health Admini stration should drop a requirement for tuberculosis skin testing of health care workers every six months in its proposed TB standard and allow some local flexibility in developing exposure control plans, advises the Centers for Disease Control and Prevention.
Obtained from the OSHA docket office in Washington, DC, the comments are slated to be delivered as testimony at an April 7, 1998, OSHA hearing by Linda Rosenstock, MD, MPH, director of the National Institute for Occupational Safety and Health. NIOSH compiled the various comments into a "consensus view" from both agencies.
While generally supporting OSHA's proposed TB standard, the CDC essentially made suggestions that would bring the rule more in line with its own TB guidelines.1,2 As many have noted in response to the proposed standard, the CDC guidelines are more flexible and have already been implemented by most infection control professionals.
Debating skin-test frequency
"We are suggesting that facilities should be able to choose between developing facility-wide or area-or-location-specific exposure control plans," the testimony states. "Providing this choice will allow program managers to target their efforts, allowing for more efficient and potentially more effective identification and control of hazards. We are also recommending that OSHA remove the six-month [TB skin test requirement] because in some settings that frequency of testing may produce excessive numbers of false positive test results. The skin testing provisions that remain would provide sufficient worker protection."
While OSHA would require six-month testing for all workers who enter a TB isolation room, the CDC guidelines allow for TB testing to be based on risk assessments that may vary the testing provisions within different areas of the institution.
"Facilities that elect to do an area-specific exposure plan may identify areas of the facility where the risk of exposure is greater than the rest of the facility, and where 6-month testing may be appropriate," Rosenstock's testimony states.
Making six-month testing option would not leave workers unprotected, as other provisions of the standard call for testing "at least" annually, after exposure incidents, or whenever a worker has signs or symptoms, she notes.
While the CDC guidelines have been effective in reducing the risk of occupational TB, there is a need for a federal OSHA standard, her testimony states.
"While some employers will observe voluntary guidelines, others will not, and the vigilance of many will wane over time," the comments state. "A mandatory standard will ensure that every employer consistently observes these fundamental principles of worker protection."
SHEA questions validity of rule
However, hospital epidemiologists have come out against the proposed rule, saying it is based on invalidated and scientifically flawed studies. Indeed, the OSHA-proposed TB rule fails to meet the agency's own established criteria for promulgation of a standard, charges the Society for Healthcare Epidemiology of America (SHEA).
In comments submitted to the OSHA docket office, SHEA concludes that "the promulgation of the proposed standard cannot be scientifically justified at this time."
The so-called "benzene" court decision (Industrial Union Department, AFL-CIO v. American Petroleum Institute, 448 U.S. 607 [1980]) established the criterion justifying the need for a standard. According to this decision, there must be substantial evidence to prove the following two conditions:
· there is a significant health risk under existing conditions;
· the issuance of a new standard will significantly reduce or eliminate that risk.
In determining this risk, OSHA has generally considered, at a minimum, a fatality risk of 1/1,000 over a 45-year working lifetime, add the authors, SHEA president Elias Abrutyn, MD, and Michael L. Tapper, MD, chairman of the SHEA AIDS/TB committee.
"We are particularly concerned that three invalidated and scientifically-flawed studies were used to estimate a nationwide risk of occupational TB," SHEA emphasizes. "In the analysis there is no effort made to include adjustment for major confounding variables, i.e., race, ethnicity, socioeconomic status, receipt of BCG and the effect they may have on the background prevalence of TB infection in the occupational group under study."
For example, SHEA says OSHA inappropriately cites TB problems at Jackson Memorial Hospital in Miami as justification for the standard.
"The data were derived during an outbreak period when TB controls were not sufficient," SHEA notes. "Subsequently, the implementation of the 1990 CDC recommendations for TB prevention were shown to be effective in controlling transmission to patients and healthcare workers. In addition, the hospital is in a geographic area where the background prevalence of TB is high and the worker population coming from the high prevalence population is expected to have a higher background rate of TB infection. Without ascertaining that the exposed and control groups were similar, the role of `exposure' in tuberculin skin test conversion rates cannot be validated."
SHEA similarly dismisses TB data from North Carolina and Washington that were cited by OSHA in its proposed rule. SHEA notes that "it appears that no effort was made to determine the validity of the information submitted."
Likewise, OSHA's assumption that one can estimate the background rate of TB infection from the number of active TB cases reported in a geographic area has not been substantiated. A high number of TB cases between 1985 and 1992 came from immigrant populations, SHEA reminds.
Fatality risk overstated
SHEA also charges that OSHA overestimated the fatality risk associated with TB infection in health care workers. The CDC uses the estimate of a 10% lifetime risk of progressing to active TB as a basis for predicting the likelihood of TB disease in the general population.
"To our knowledge there are no population-specific estimates that can be applied to healthcare workers," SHEA states. "However, it is a well established fact that health and socioeconomic status are important determinants of TB infection progressing to disease. Therefore, healthcare workers, as a generally healthier and socioeconomically-stable population, may have a lower risk for disease progression than the general population."
In addition, OSHA fails to consider the impact of INH preventive therapy, now recommended for all skin-test converters regardless of age, SHEA says. At least 80% of subsequent TB disease can be prevented with INH chemoprophylaxis.
SHEA goes on to say the proposed fit-testing requirements for respirators are unnecessary and costly, and lack scientific support. The proposed frequency and routine use of two-step testing are also unnecessary and excessive.
"Certain aspects of the standard are inconsistent with accepted standards of practice, fail to consider the multitude of factors and confounding influences that affect risk and the interpretation of TB risk to healthcare workers, and inappropriately infringe on patient care and professional judgement," SHEA concludes. "As written, the proposed standard lacks credibility in the scientific community and will be difficult to implement and enforce."
Putting the situation in historical perspective, SHEA observed that between 1985 and 1992 there was a resurgence of TB in the United States, due in part to an increased incidence of disease in immigrant populations, the impact of the HIV epidemic, and perhaps most significantly, an erosion of the public health infrastructure that had contributed to the control and decline of tuberculosis earlier in this century. In addition, the low clinical index of suspicion of tuberculosis in symptomatic individuals (principally people with HIV infection) undoubtedly contributed to the transmission of TB in a variety of occupational settings, most predominantly in hospitals, SHEA claims.
TB levels at an all-time low
"Transmission of TB to healthcare workers occurred during this period of resurgence and posed a legitimate cause for concern," SHEA stated. "However, through aggressive public health and treatment measures, there has been a steady decline in the incidence of TB to the lowest levels in history. Data from the American Hospital Association demonstrate that the overwhelming majority of healthcare facilities have implemented the hierarchy of controls, appropriate to their facility's level of risk, as recommended by the 1994 CDC guidelines. . . . Healthcare workers have never been better protected from TB than they are today. OSHA has provided no evidence that exceeding these recommendations, and imposing an additional and unnecessary burden on healthcare facilities, will have any additional impact on the protection of healthcare workers."
References
1. Department of Labor. Occupational Safety and Health Administration. Occupational exposure to tuberculosis; proposed rule. 62 Fed Reg 54,160-54,307 (Oct. 17, 1997).
2. Centers for Disease Control and Prevention. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health care facilities, 1994. MMWR 1994; 43:(No. RR-13) 1-133.
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