Two-step tuberculin skin testing of injection drug users recruited from community-based settings
Setting: Cross-sectional study of drug users recruited from street-based settings in four US cities: Denver, Portland, Oakland and San Francisco.
Objective: To evaluate responses to two-step tuberculin skin testing among HIV-positive and HIV-negative injection drug users.
Design: Subjects were recruited from existing studies of HIV and risk behaviors for tuberculin skin testing. Those with a negative initial tuberculin test were referred for a second skin test 1–3 weeks later. A positive tuberculin test was defined as 10 mm, or 5 mm if the subject was HIV-positive.
Results: Of 997 persons receiving an initial tuberculin test, 13% had a positive response. Of 644 persons receiving a second tuberculin test, 8% had a positive response, with rates as high as 14% among those from Oakland and 12% among African Americans. HIV-positive subjects were less likely to have skin test responses 10 mm on the initial test (P = 0.03), or increases between the initial and second test of 10 mm (P = 0.06).
Conclusion: Boosting occurred in both HIV-positive and HIV-negative injection drug users. Two-step testing should be considered for this population, particularly those on whom repeat tuberculin testing will be performed.
Lifson, AR., Grant, SM., Lorvick, J., Pinto, FD., He, H., Thompson, S., ... Watters, JK. (1997). Two-step tuberculin skin testing of injection drug users recruited from community-based settings. International Journal of Tuberculosis and Lung Disease, 1(2), 128-134.