Impact of Choice of Test for Latent Tuberculosis Infection on Treatment Acceptance and Completion

Objective: The aim of this study is to assess whether choice of test for tuberculosis (TB) infection affects decisions to accept and complete treatment among contacts to TB cases.

Methods: Retrospective study is conducted in which TB contacts, ⩾15 years old during 2005 and 2009, were tested for infection with either a tuberculin skin test (TST) or an interferon-gamma release assay test, the QuantiFERON-TB Gold In-Tube (QFT-GIT).

Results: Of 658 persons with valid test results, 185 (28%) had positive results, including 128 of 406 (32%) who had TST and 57 of 252 (23%) who received QFT-GIT. Treatment acceptance was 43 of 57 (75%) among QFT-GIT-positive and 97 of 128 (76%) among TST-positive persons (risk ratio [RR] = 1.0, 95% confidence interval [CI], 0.83-1.2). Treatment completion was 56% among QFT-GIT-positive (32 of 57) and 59% (75 of 128) among TST-positive persons (RR = 0.96, 95% CI, 0.73-1.26).

Discussion: Our study showed no difference in proportions of TB contacts ⩾15 years old with positive TST results who accepted or completed LTBI treatment compared with those with positive QFT-GIT results. Future studies should include high-risk persons with no known TB exposure, who constitute the main reservoir for TB cases in the United States.