N. Salomon et al., Prevalence and risk factors for positive tuberculin skin tests among active drug users at a syringe exchange program, INT J TUBE, 4(1), 2000, pp. 47-54
Citations number
35
Categorie Soggetti
Cardiovascular & Respiratory Systems
Journal title
INTERNATIONAL JOURNAL OF TUBERCULOSIS AND LUNG DISEASE
OBJECTIVES: To evaluate the prevalence and predictors of tuberculin skin te
st (TST) reactions greater than or equal to 10 mm among active injection dr
ug users (IDUs) at a syringe exchange program in New York City.
METHODS: From August 1995 to January 1996, participants were offered TB scr
eening, an interview and received $15.00 upon returning for skin test inter
pretation.
RESULTS: 610/650 (94%) consented to screening. Of the 566 (93%) who returne
d for skin test readings, skin test data were available for 564 (99.8%); 14
% (95%CI 11.6-17.1) had TSTs greater than or equal to 10 mm. When the great
er than or equal to 5 mm threshold for interpretation of TST among HIV-infe
cted persons was used, the prevalence of TST positivity increased by only 1
%. In univariate analysis, the prevalence of TST greater than or equal to 1
0 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 logist
ic 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 greater than or equal to 10 mm
. In the model with duration of IDU, a history of TST positivity (OR 8.82;
95%CI 4.74;1-16.41; 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 gre
ater than or equal to 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 thi
s cohort of active drug users. Increased prevalence of TB infection with ag
e 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.