Clinical Edge

Summaries of Must-Read Clinical Literature, Guidelines, and FDA Actions

Primary Care Screening of Latent Tuberculosis

JAMA; ePub 2016 Sep 6; Kahwati, Feltner, et al

Publish date:

There were no studies that evaluated the benefits and harms of screening for latent tuberculosis infection (LTBI) in a primary care setting compared with no screening in a review of 72 studies (n=51,711), thus supporting the US Preventive Services Task Force (USPSTF) final recommendation that recommends screening for LTBI in populations at increased risk. Results included:

• Pooled estimates for sensitivity of the tuberculin skin test (TST) at both 5-mm and 10-mm induration thresholds were 0.79 and those for interferon-gamma release assays (IGRAs) ranged from 0.77 to 0.90.

• Pooled estimates for specificity of the TST at the 10-mm and 15-mm thresholds and the IGRAs ranged from 0.95 to 0.99.

• There was a reduction in absolute risk of active tuberculosis (TB) at 5 years from 1.4% to 0.5% and an increase in absolute risk for hepatoxicity from 0.1% to 0.5% for 24 weeks of daily isoniazid when compared to placebo in a randomized clinical trail of 24 weeks of isoniazid in individuals with pulmonary fibrotic lesions and LTBI (n=27,830).

• 3 months of once-weekly rifapentine plus isoniazid was noninferior to 9 months of isoniazid alone for preventing active TB.

Citation: Kahwati LC, Feltner C, Halpern M, et al. Primary care screening and treatment for latent tuberculosis infection in adults. Evidence report and systematic review for the US Preventive Services Task Force. JAMA. 2016;316(9):970-983. doi:10.1001/jama.2016.10357.

Commentary: Screening and treating latent tuberculosis infection (LTBI) in patients at higher risk for developing active tuberculosis is recommended by multiple professional societies as a means of TB control. The prevalence estimate for LTBI in the overall patient population from a US national survey is approximately 5%1 (approximately 12 million persons). Over their lifetime, approximately 5 to 10% of non-immunocompromised patients diagnosed with LTBI will develop active TB in the absence of treatment. This evidence-based review by the USPSTF reports that current screening tests, which now include interferon-gamma release assays (IGRA) in addition to tuberculin skin tests (TST), are accurate and very specific.2 It also reports that treatment of LTBI reduces the risk for progression to active disease with only a small amount of associated harm.2 This analysis will continue to support the current practice of screening patients at increased risk for developing TB infection (including immunocompromised patients, recent contacts of patients with active TB, recent arrivals from countries with high prevalence of TB, injection drug users, people who reside in high-risk congregate settings including prisons, nursing homes, and homeless shelters) and treating those diagnosed with LTBI (asymptomatic patient with positive IGRA or TST without evidence of active infection). The CDC recommendations for treatment of LTBI include 9 months of daily isoniazid, 4 months of daily rifampin, or 12 weeks of once weekly isoniazid and rifapentine, the latter requiring directly observed therapy (DOT) vs self-administered means for the 2 other regimens. The shorter combined isoniazid/rifapentine treatment has been shown to be noninferior to monotherapy with INH for prevention of active TB. If data also support that completion rates with self-administered isoniazid/rifapentine are as effective as DOT, then perhaps we can anticipate some changes in recommendations for this shorter course. In the interim, continued efforts to improve diagnostics, prognostic markers, and treatments will need to be funded for this potentially fatal infection.3 —Fred A. Lopez, MD

1. Miramontes R, Hill AN, Woodruff RS, et al. Tuberculosis infection in the United States: Prevalence estimates from the National Health and Nutrition Examination Survey, 2011-2012. PlosOne. 2015;10:e0140881.

2. US Preventive Services Task Force. Screening for latent tuberculosis infection in adults—: US Preventive Services Task Force recommendation statement. JAMA. 2016;316(9):962-969. doi:10.1001/jama.2016.11046.

3. Blumberg HM, Ernst JD. The challenge of latent TB infection. JAMA. 2016;316(9):931-933. doi:10.1001/jama.2016.11021.

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