CDC guidelines may mean fewer TB tests

Update calls for risk-assessment, 'periodic' fit-tests

Hospitals will perform fewer tuberculosis screening tests but may provide more training for TB skin test placers and readers under new guidelines released by the Centers for Disease Control and Prevention (CDC) in Atlanta.

The guidelines also more clearly link the CDC's recommendation for "periodic" fit-testing of respirators to the requirement by the U.S. Occupational Safety and Health Administration (OSHA) requirement for annual fit-testing.

This is the first update of the Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Healthcare Facilities since 1994, when the nation was fighting a resurgence of TB. The new document reflects current realities, such as lower overall rates of TB in the United States but higher rates among subpopulations, such as foreign-born Americans.

"It's our hope that the guidelines are more flexible," says Michael Iademarco, MD, MPH, CDC's associate director for science and an author of the guidelines. "You need flexibility to design, for each setting, the proper measures to optimally prevent the transmission of TB."

Risk assessment receives major emphasis in the guidelines, which call for only baseline testing of health care workers if a facility is "low risk." Even hospitals that treat TB patients could eliminate annual testing of some employees, such as those with no patient contact or who work in areas where they would not encounter TB patients.

That doesn't mean low-risk facilities are off the hook when it comes to TB prevention, cautions Iademarco, who is a captain in the U.S. Public Health Service. Rather, they should divert those resources used for screening to other TB control measures, such as regular risk assessments, education of health care workers, and careful monitoring.

"There's a tendency for people to focus on the TST [tuberculin skin test] and the fit-testing. But those two things are just tools in the larger programmatic effort to prevent transmission," he says. "Design a program that works for your setting and measure that it works."

An annual period of fit-testing?

The new guidelines include some subtle but important changes from the draft guidelines, which were released in late 2004. They recommend that health care settings "perform fit-testing during the initial respiratory protection program training and periodically thereafter in accordance with federal, state, and local regulations." The document then references the OSHA respiratory protection standard.

The CDC also recommends that patients with suspected or confirmed TB wear a surgical mask, if possible, when they are not in an isolation room. "Surgical or procedure masks are designed to prevent respiratory secretions of the wearer from entering the air," the guidelines state.

Bill Borwegen, MPH, health and safety director of the Service Employees International Union (SEIU), was pleased with that wording. "I think the CDC makes an eloquent argument about why periodic fit-testing is crucial," he says, noting that the CDC guidelines and OSHA standard "dovetail and complement each other."

Others also interpret the new guidelines as supporting annual fit-testing. "I think we have to assume [the required period for fit-testing is] annual," says William Buchta, MD, MPH, medical director of the Employee Occupational Health Service at the Mayo Clinic in Rochester, MN. "How can you assume anything else?"

Congressional action has temporarily prevented OSHA from spending federal funds to enforce the annual fit-testing rule. But that does not apply to state-plan states, such as Minnesota. Mayo has reduced the number of health care workers who participate in the respiratory protection program and conducts more "on-demand" fit-testing, as needed, Buchta says.

Iademarco contends that the guidelines do not support annual fit-testing. They are silent on the "periodicity" because of the lack of sufficient evidence, he says.

"Periodic is left undefined," he says. "The evidence and expert opinion did not allow for further definition. So the weight of the evidence leads us to recommend initial and periodic fit-testing."

The reference to the OSHA standard is merely a function of CDC protocol, he says. "There is a CDC policy that says in written guidance you must reference and acknowledge other potentially overlapping policies," he says.

Foreign-born HCWs at risk

Overall, the TB guidelines address the current realities of TB transmission, which has declined nationally but remains a concern in some subpopulations, such as the foreign-born.

"Preventing the transmission of tuberculosis among health care workers is one of the highest priorities," says Iademarco. "We need to do that in the context of the changing epidemiology of tuberculosis."

Foreign-born health care workers may have a greater risk of acquiring TB infection from the community than from their workplace, Iademarco notes. Employers need to distinguish between false positive screening tests due to BCG vaccination and true positives that should lead to evaluation for treatment of latent TB infection.

Meanwhile, health care workers must maintain a high level of suspicion that enables them to detect TB disease. "As we move towards elimination [of TB], health care workers are on the front lines of recognizing tuberculosis," he says.

The new guidelines include the most recent information on Quantiferon-TB Gold, which currently is the only blood test available to detect TB infection. The test is more specific than skin tests and distinguishes between Mycobacterium tuberculosis infection and BCG vaccination.

The CDC also addressed concerns that were raised in response to the draft guidelines, which contain tougher training standards for those who place and read TB skin tests. But the agency backed off of more strongly worded recommendations and instead emphasized that the "suggested TST training recommendations are not mandatory." Rather, the training levels suggested would be for a "model" program, the guidelines state.