APIC challenges periodic’ TB respirator fit-testing

Linking TB draft to bioterror also a stretch

The Association for Professionals in Infection Control and Epidemiology (APIC) strongly challenged the rationale for "periodic" respirator fit-testing in draft public health guidelines for preventing tuberculosis transmission in health care facilities.

The Centers for Disease Control and Prevention (CDC) recommends in the draft document that health care workers be fit tested "during the initial respiratory protection program training and periodically thereafter based on the risk assessment for the setting."

The Occupational Safety and Health Administration (OSHA) was requiring annual fit-testing, but APIC successfully lobbied to kill the funding to enforce the measure.

In comments submitted to the CDC, APIC emphasized, "There is no evidence that fit-testing, let alone routine, periodic fit-testing, is necessary to control transmission of TB in health care facilities." Moreover, studies have not been able to identify reliable and reproducible fit-testing methods, even in the controlled research setting, APIC stressed.

The association cited a study that concluded, "None of the five fit-testing methods met the criteria for determining whether a fit-test adequately screened out poorly fitting respirators."1

Investigators have demonstrated that respirators with inherently good fit characteristics are more likely to protect workers than use of poor fitting respirators with fit-testing.

The CDC needs to establish fit-test criteria and make these results available to the public to enhance likelihood of benefit to users, APIC recommended. "CDC should not recommend routine, periodic fit testing in the absence of proven benefit, need or reliable methodology," APIC stated.

APIC pointed out that the N95 respirators — which became ingrained in health care after TB resurged in the early 1990s — have never been proven necessary to control even multidrug-resistant TB (MDRTB).

"Epidemiologic evidence has clearly demonstrated that TB and MDRTB outbreaks could be controlled with the use of administrative and environmental control measures using submicron surgical masks," APIC commented. "The evidence for N95 or other industrial respirators has not been established in clinical settings."

The draft TB guidelines, which were closed to comment as of Feb. 4, 2005, pointed out that infection control efforts against TB have a new relevance to bioterrorism preparedness.

"Many of the activities and recommendations for the prevention and control of TB will also be useful for preventing transmission of agents of bioterrorism and diseases such as smallpox and SARS," the CDC guidelines state.

Part of the reasoning behind this is that smallpox and severe acute respiratory syndrome (SARS) "are transmitted by air" and thus environmental control measures like controlled air isolation rooms can prevent transmission, the CDC reasoned.

However, APIC pointed out that SARS and smallpox are predominately transmitted via contact and droplet spread.

"This paragraph implies that the airborne route is predominant," APIC stated. "In addition, CDC has recommended use of surgical masks when N95 respirators are in short supply. Need for N95 is not clearly established by studies in countries where SARS was epidemic. It may be prudent to eliminate this section as it is misleading, recommendations are covered in other CDC guidance documents, and the focus of this document is tuberculosis control."

In addition, APIC offered the following general comments and recommendations to the CDC regarding the new TB guidelines:

  • Length

The draft guidelines are extremely comprehensive, but lengthy. The length and structure make it extremely difficult to identify the essential or critical components and recommendations.

It would help if all essential elements and recommendations were in the main body of the document and if the appendices were utilized to provide additional explanation (i.e., to supplement the main text). In addition, an executive summary with recommendations would be extremely helpful.

  • QuantiFERON and other assays

Given the recent licensure of the QuantiFERON-Gold whole-blood assay, the final guidelines should include updated recommendations for the use of this test. The QFT-Gold has the potential to be extremely useful in differentiating between prior exposure/infection with BCG/other atypical mycobacteria and M. tuberculosis.

In addition, it may be helpful to add a statement reflecting the future option to use newer tests/ technology when licensed and recommended by the CDC since third generation QFT and other tests are under development, evaluation and/or review.

The recommendations in tables and text need to address the use of the QFT in follow-up of unprotected exposures. If baseline TB screening has been performed using the QFT, the follow-up post-exposure testing also should be performed with a QFT. Otherwise, if a TB skin test (TST) is the only post-exposure test option, the interpretation of the results will be complicated further by attempting to correlate two different test methods. These difficulties will be complicated additionally by potential boosting if two TSTs are needed post-exposure.

  • "Airborne" terminology

For consistency with the previous and current working draft of the CDC Guideline to Prevent Transmission of Infectious Agents in Healthcare Settings, the term "Airborne Precautions" should be used instead of "Airborne Infection Isolation."

Both documents will use the term "Airborne Infection Isolation Room (AIIR)" to describe the appropriate room placement for patients on airborne precautions. This can be corroborated with guideline authors on the Healthcare Infection Control Practices Advisory Committee or in the Division of Healthcare Quality Promotion.

  • Emergency departments and risk classification

Low-risk facilities may have medium risk emergency departments, depending upon community risks and availability of resources. The emergency department/urgent care center should be separated from the rest of the facility in determining the risk classification and also in development of control measures.

For example, a facility may not admit suspected or confirmed TB patients, but they may be seen in the emergency department and, if admission is warranted, referred elsewhere.

  • References to OSHA requirements

The CDC guidelines should be based upon evidence, not on standards promulgated for general industry.

The historical paragraph regarding the proposed OSHA TB rule is not relevant to this document, does not provide added value, and may only confuse future readers.

OSHA only regulates private industry. In some states, but not all, there are public entities that regulate public practice settings, in other states, there are no requirements.

The regulations and requirements can differ for private and public industry settings and employers. Therefore, throughout this entire guidance document, policy and recommendations should not be based upon OSHA regulatory requirements as they may or may not be applicable.

Reference

1. Coffey CC, Lawrence RB, Zhuang Z, et al. Comparison of five methods for fit-testing N95 filtering-facepiece respirators. Appl Occup Environ Hyg 2002; 17(10):723-730.