AHA: OSHA rule flunks TB skin tests

Could rule spur false-positives, needless treatment?

Tuberculosis skin-testing requirements for health care workers proposed by the Occupational Safety and Health Administration could lead to inaccurate results and unnecessary treatments in health care settings with minimal TB risk, the American Hospital Association warns.1

"Our greatest concern is the skin-testing requirement," said Gina Pugliese, RN, MS, CIC, an infection control consultant who testified on behalf of the AHA at an April 13, 1998, OSHA hearing in Washington, DC. "Currently, almost half of the counties in the United States have no reported cases of TB. Under OSHA's proposal, hospitals in these counties will be forced to conduct baseline testing of workers, regardless of the risk of TB in the community. Even if limited to workers in `intake areas,' this requirement imposes an unnecessary burden on hospitals with minimal TB risk and has the potential for inaccurate results."

For example, OSHA's proposal for baseline skin testing in all facilities would subject thousands of health care workers who are at minimal or no risk for TB to unnecessary skin testing, she noted. The Centers for Disease Control and Prevention has recommended against routinely testing populations at low risk of TB because they are more likely to have false-positive reactions and then may be inappropriately treated with anti-TB drugs, she reminded. Such testing of low-risk workers would likely spread across larger populations if TB continues to decline in the United States after the standard is in place, she added.

"We recommend that OSHA tie its baseline skin-testing requirements [to] the risk of TB so that declines in TB incidence will result in declines in baseline skin-testing of workers," she said.

Similarly, OSHA's proposal to require skin testing every six months for workers who may enter TB isolation rooms or perform a high-hazard procedure - regardless of the number of TB patients in the area or facility - would result in skin testing of workers in facilities with only one case of TB, Pugliese added. That proposed OSHA requirement is also inconsistent with CDC guidelines, which recommend repeat skin testing on an annual basis for workers in "low risk" facilities that admit fewer than six patients to an area during the preceding year. In addition, the CDC recommends TB skin testing every three months for workers in "high risk" facilities that may have clusters of skin-test conversions, higher conversion rates in groups with occupational exposure, or person-to-person transmission.

"OSHA's effort to simplify the CDC risk categories for enforcement purposes would impose an unnecessary burden on low-risk facilities while simultaneously permitting higher-risk facilities to reduce the frequency of their skin testing surveillance efforts," Pugliese testified.

OSHA underestimates costs

Delivering related testimony at the same hearing was Elizabeth Fuss, RN, MS, CIC, who represented the Greater Baltimore chapter of the Association for Professionals in Infection Control and Epidemiology.

"We also have concerns about OSHA's call for TB skin testing to be done every six months," Fuss testified. "This provision seems to be based on the erroneous assumption that more frequent testing will more readily detect transmission in a healthcare facility. We believe that to do TB skin testing every six months is not necessary, is not scientifically justified or supported in medical literature, and is certainly not a reasonable or efficient use of limited healthcare dollars."

For example, a 100-bed hospital in Baltimore that spent $5,000 for TB skin testing in 1997 would see that cost almost double under the provisions in the OSHA rule, Fuss said. While OSHA has estimated a minimal cost impact of the standard, Fuss reminded that another 372-bed Baltimore hospital spent $11,000 for TB skin testing in 1997.

"These figures indicate that OSHA's cost estimates of $2,408 per establishment for implementation of the entire TB standard are extremely low," she said.

Also, most hospitals have already conducted TB risk assessments and established a frequency of repeat skin testing and other control measures based on CDC guidelines, Pugliese noted.2

"It is unreasonable to expect employers to change the frequency of repeat skin testing based on a new standard without any additional evidence that this will reduce the risk of TB to workers," she said. "We suggest that OSHA change the criterion for repeat skin testing to be consistent with the CDC guidelines, that is, using 'six or more cases in an area in the past year' as the criterion for requiring repeat skin testing every six months."

Hospitals are also concerned about OSHA's proposed requirement to do two-step baseline skin testing for all workers with a prior negative skin test, Pugliese said, noting that many prefer the CDC recommendation that the frequency of "boosting" in a facility should be used to determine the need for two-step baseline skin testing. Over time, TB skin testing may boost reactions in people with childhood infection, for example, and that can be misinterpreted as a test conversion from a recent exposure, according to the CDC. Two-step testing can be used to reduce the likelihood of misinterpreting a boosted reaction.

"The AHA believes that employers should continue to be able to use data on the frequency of boosting in their work site to determine the need for two-step testing, using such factors as the types of workers, their age, and experience with boosting," Pugliese said. "Two-step skin testing has become particularly important in health care settings with workers at risk of occupational exposure to TB from countries where TB is endemic and who have received prior BCG vaccination."

Finally, OSHA's proposal for skin testing within 30 days of termination of employment is problematic and will be burdensome to implement, Pugliese warned. Such a requirement for skin testing at termination is unrelated to the level of risk in a facility, and thus could also contribute to testing large numbers of low-risk people. Regardless, because skin-test conversions may occur as long as 10 weeks after infection, testing at termination would not necessarily identify workers who may have been occupationally infected. In addition, terminated workers have virtually no incentive to cooperate, particularly if their last day of employment is the day on which they are notified of their termination, she said.

"This requirement seems to establish an unnecessary and undesirable precedent," she testified. "No other standard, including OSHA's bloodborne pathogen standard, requires screening workers for an occupationally acquired infection at or after termination."


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.