Negative TB Skin Tests Still Elicit a Higher Risk For In-Hospital Death

Negative tuberculin skin test (TST) results, increasing age, and malnutrition are associated with the risk of in-hospital mortality among patients with tuberculosis (TB), according to a recent study.

Findings were presented at ID Week, which took place from October 4 to 8, 2017, in San Diego, California.
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A negative TST is known to be associated with poor outcomes in those with TB. However, it is not yet known whether a negative TST is associated with in-hospital mortality in patients with active disease.

For their study, the researchers evaluated 961 patients with active TB at the University of Texas Health Science Center at Tyler from January 1, 1985, to December 31, 2010. Also included in the analysis were a 25% simple random sample of patients with uncomplicated TB and 100% of 3 groups with complicated TB disease, including drug-resistant TB, HIV-coinfection, and serum drug-level monitoring.

A negative TST was defined as less than 10 mm induration. Potential associations between sociodemographic and clinical factors, TST, and hospital mortality were investigated.

A total of 635 individuals were included in the final analysis, of whom 19.2% had negative TST results and 2.9% had died while hospitalized. Notable characteristics were foreign-birth (47.9%), malnutrition (22.7%), homelessness (18.0%), positive human immunodeficiency virus (HIV) status (2.5 %), positive acid-fast bacillus (AFB) smear (48.7%), prior history of TB (16.7%), and multi-drug–resistant TB (1.7%).

Ultimately, the researchers found that negative TST results, age, and malnutrition were significantly associated with in-hospital mortality. They noted that the risk for in-hospital mortality was 2.2-fold higher among patients with a negative TST, compared with those with a positive TST.

“Negative TST results, as well as increasing age and malnutrition were significantly associated with in-hospital mortality, possibly reflecting weakened cellular immune reaction to Mycobacterium tuberculosis antigens,” the researchers concluded. “TST results may identify patients at higher risk of death.”

—Christina Vogt

Reference:

Joo SJ, Kim J, Cegielski P. Risk factors associated with in-hospital mortality among patients with active TB disease: 25-year experience in the US. Paper presented at: ID Week 2017; October 4-8, 2017; San Diego, CA. https://idsa.confex.com/idsa/2017/webprogram/Paper63129.html.