By Carol A. Kemper, MD, FACP

Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center

Dr. Kemper reports no financial relationships relevant to this field of study.

SOURCE: Screening for latent tuberculosis infection in adults. U.S. Preventive Services Task Force Recommendation Statement. JAMA 2016;316:962-969.

If corporate America wishes to embrace globalization, they should heed the global disease burden, at least to the degree that it puts their own workforce at risk from tuberculosis exposure. Too often in Silicon Valley, we see another case of active tuberculosis (TB) in a visiting student, or a young high-tech worker on an H-1B visa, or in an elderly immigrant, none of whom have been screened and treated for latent TB (LTBI).

This updated statement from the United States Preventive Services Task Force (USPSTF) advocates, with “moderate certainty,” for a “moderate net benefit” for the screening and treatment of persons at increased risk for TB. Based on a current assessment of the benefits and harms, screening and treatment of individuals with latent TB is of overall benefit, regardless of age, even if they are currently asymptomatic or considered lower risk.

Based on 2011-2012 National Health and Nutrition Examination Survey data, the prevalence of LTBI in the United States is estimated to be between 4.7-5.0%. Approximately 5-10% of these will progress to active TB or reactivation disease. Rates of progression to active disease are higher in the elderly, and in those with diabetes, kidney disease, and immunosuppression. Not only does the risk of reactivation increase to 20-25% by the time you are in your 80s, but the risk of mortality also is considerably increased. Although active TB is considered a treatable disease, it is important to recognize the overall mortality for active TB is approximately 4%, even with treatment.

In 2015, 66% of cases of active TB occurred in foreign-born persons, and the case rate of active TB was approximately 13 times higher in foreign-born persons compared with those born in the United States. More than half of those who develop active TB are from five countries: the Philippines, Vietnam, India, China, and Mexico. The prevalence of LTBI also is greater in the homeless, persons in long-term care facilities, and those in correctional facilities.

The USPSTF concluded that the two types of screening tests (skin test and IGRA tests) are fairly sensitive and specific, and the evidence for harm in being screened is nil. The risk for harm in the treatment of LTBI has been well characterized, and is comparatively less than the risk of harm from developing active or reactivation TB. In concrete numbers, if 100,000 persons at increased risk for TB were screened and treated for LTBI, 52 to 146 cases of active TB would be prevented, seven to 67 cases of hepatotoxicity would occur, and 111 persons would discontinue treatment for adverse effects. To prevent one case of active TB, approximately 111-314 persons (depending on risk factors) would need to be treated for LTBI. In contrast, the number of persons needed to cause one case of hepatotoxicity from LTBI treatment would range from 279-2,531 (depending on the treatment).

Make it your job — and the job of your primary care colleagues — to screen persons at risk for LTBI, especially anyone born in a foreign country endemic for TB, regardless of age, and make an effort to target those individuals who are allowed to enter this country without screening for LTBI.