Latent tuberculosis among injection drug users in a methadone maintenance treatment program, Taipei, Taiwan: TSPOT.TB versus tuberculin skin test.

BACKGROUND

Taiwan has a growing HIV/AIDS epidemic that has recently shifted to an increase among injection drug users (IDUs). IDUs co-infected with HIV and tuberculosis (TB) have a high risk of progression from latent tuberculosis infection (LTBI) to active TB.

METHODS

This study aimed to determine the prevalence and correlates of LTBI among IDUs by TSPOT.TB and tuberculin skin test (TST), in a large methadone program in Taipei, Taiwan. Consenting participants were interviewed by a trained worker regarding sociodemographics, substance use history, and health factors.

RESULTS

Multivariate analysis was used to determine risks associated with each test outcome. Of 287 participants, 165 (58.7%) tested TSPOT.TB-positive and 244 (85.0%) tested TST-positive. The mean age was 44 y, and 7.3% were HIV-infected. Kappa statistics indicated slight concordance between TSPOT.TB and TST. In multivariate analysis, after controlling for potential confounders, TSPOT.TB positivity was significantly associated with age ≥ 50 y (reference, 20-34 y). A history of ever having had contact with a TB-infected person was associated with TST positivity, whereas HIV infection was inversely associated with TSPOT.TB positivity and TST positivity.

CONCLUSIONS

This study shows a high prevalence of LTBI in individuals at risk for HIV infection in Taipei, Taiwan. Future TB prevention programs should particularly focus on IDUs.