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CDC draft TB guidelines change risk assessments

No need for annual TB testing in low-risk settings

While respirator fit-testing has been the most controversial issue, infection control professionals should be aware that a new tuberculosis risk-assessment strategy is outlined in draft TB guidelines by the Centers for Disease Control and Prevention (CDC). The risk-assessment portion of the guideline is the component that determines the frequency of worker skin testing and other infection control measures.

"Risk assessments originally varied by setting, but now we have them applying to the entire facility," said Adelisa Panlilio, MD, MPH, medical epidemiologist in the CDC division of healthcare quality promotion. "We changed the risk assessment and linked it to the frequency of recommended TB skin test screening of health care personnel."

Panlilio outlined the key risk assessment elements recently in Boston at the 2004 annual meeting of the Infectious Disease Society of America. "Certainly, we know that the greatest risk of transmission is posed by the presence of the unsuspected and/or undiagnosed infectious patient," she said. "And that won’t change. The principles of preventing transmission that we recommend are the same as in the ’94 [CDC TB] guidelines."

However, one new feature is that low-risk settings need not do periodic (e.g., annual) TB skin testing of health care workers. Baseline testing at hire still should be performed for health care workers who might have contact with TB patients regardless of the risk classification of the setting.

"Periodic screening is optional in low TB incidence areas," she said. "That is new. We were concerned about the high rate of testing of health care personnel in areas with low prevalence, where all you are finding are usually false positives. There is a lot of effort and expense expended in such settings, and we are trying to discourage that."

Every type of health care setting should conduct initial and ongoing evaluations of the risk for transmission of TB regardless of whether patients with TB will be encountered there, the CDC recommends.

"The risk assessment should be performed initially and then periodically at least annually," Panlilio said. "This includes assessing the community TB profile. What is the prevalence of TB in the community? What is the proportion of cases or isolates that are multidrug resistant? Look at TB patient-specific indicators — the kind of patients that may be seen in the facility to determine the risk classification for the facility."

Dividing line set at 200 beds

Facilities will fall into one of three risk classifications, "low," "medium," or "ongoing transmission." The latter essentially is a high-risk category, but it is designed as a temporary designation until controls rein in TB and bring the risk down, she explained. The dividing line for various infection control measures under the categories was drawn at 200 hospital beds.

"Approximately half the hospitals in the U.S. have 200 or more beds," she said. "This was an arbitrary decision, but we had to make a cutoff somewhere. So if you have a facility with less then 200 beds, and see fewer than three infectious TB patients a year, you are in the low-risk category. Of if you have more than 200 beds and see fewer than six [TB] patients a year you are in the low-risk category."

By the same token, medium-risk facilities are either those with less than 200 beds that see three or more TB patients annually or hospitals with 200 or more beds that see at least six TB patients a year. "The higher risk, which should really be a temporary category — is if there is evidence of ongoing transmission — regardless of the setting," Panlilio added.

While periodic screening of workers in low-risk settings is not recommended, medium-risk facilities should test workers annually. More frequent skin testing is expected to be done if there is ongoing transmission and contact investigations are under way.

According to the CDC draft guidelines, the following steps are among those that should be taken in performing a risk assessment in settings where TB patients may be encountered:

In collaboration with the state or local health department, review the community profile of TB disease.
Review the number of patients with suspected or confirmed TB disease who have been treated in the setting over at least the last five years.
Determine if people with unrecognized TB disease have been admitted to or were encountered in the setting in the last year.
Determine which HCWs need to be included in a TB screening program and the frequency of screening (based on risk classification, see II.B.3).
Ensure the prompt recognition and evaluation of suspected episodes of health careassociated transmission of M. tuberculosis.
Identify areas in the setting with an increased risk for health careassociated transmission of M. tuberculosis and target them for improved TB infection controls.
Determine the number of AII rooms needed for the facility.
Determine the types of environmental controls other than AII rooms needed.
Determine which HCWs need to be included in the respiratory protection program.

(Editor’s note: The CDC draft, Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005, is at www.cdc.gov/nchstp/tb/Federal_Register/default.htm. The comment period ends Feb. 4, 2005.)