Prevalence and risk factors for positive tuberculin skin tests among active drug users at a syringe exchange program.
OBJECTIVE
To evaluate the prevalence and predictors of tuberculin skin test (TST) reactions > or =10 mm among active injection drug users (IDUs) at a syringe exchange program in New York City.


METHODS
From August 1995 to January 1996, participants were offered TB screening, an interview, and received $15.00 upon returning for skin test interpretation.


RESULTS
610/650 (94%) consented to screening. Of the 566 (93%) who returned for skin test readings, skin test data were available for 564 (99.8%); 14% (95% CI 11.6-17.4) had TSTs > or =10 mm. When the > or =5 mm threshold for interpretation of TST among HIV-infected persons was used, the prevalence of TST positivity increased by only 1%. In univariate analysis, the prevalence of TST > or =10 mm increased with age and with increasing years of IDU (both P = 0.001). Because of a strong correlation between age and duration of IDU, two logistic regression models were examined. In the model with age alone, a history of self-reported TST positivity (OR 8.88; 95% CI 4.9-16.09; P = 0.0001) and increasing age (OR per 10 years increase in age, 1.69; 95% CI 1.24-2.29; P = 0.0008) were independent predictors of TSTs > or =10 mm. In the model with duration of IDU, a history of TST positivity (OR 8.82; 95% CI 4.74-16.41; P = 0.0001) and duration of IDU (OR per 10 years of IDU, 1.46; 95% CI 1.10-1.94; P = 0.0081) were independent predictors of TST > or =10 mm.


CONCLUSIONS
Use of the reduced cutoff point for TST positivity from 10 mm to 5 mm did not significantly affect the prevalence of positive TSTs in this cohort of active drug users. Increased prevalence of TB infection with age suggests a high annual incidence of TB infection in this population, and the increased risk of TB infection with increasing duration of IDU suggests that the duration spent in IDU environments may increase infection risk.
Salomon
N
N
Department of Medicine, Beth Israel Medical Center, New York, New York 10003, USA. nsalomon@bethisraelny.org
Perlman
D C
DC
Friedmann
P
P
Ziluck
V
V
Des Jarlais
D C
DC
D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008403:Mass Screening; D018671:Needle-Exchange Programs; D009519:New York City / Q000453:epidemiology; D015995:Prevalence; D012307:Risk Factors; D012959:Socioeconomic Factors; D015819:Substance Abuse, Intravenous / Q000453:epidemiology*; D013997:Time Factors; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis / Q000453:epidemiology*