Prevalence of tuberculin positivity and skin test anergy in HIV-1-seropositive and -seronegative intravenous drug users.
OBJECTIVE
--To identify differences in purified protein derivative (PPD) tuberculin positivity and skin test anergy rates by human immunodeficiency virus (HIV) serostatus, CD4+ lymphocyte count, and other risk factors in intravenous drug users (IVDUs); and to evaluate the appropriateness of the Centers for Disease Control (CDC)--recommended definition for a positive PPD tuberculin skin test result in HIV-1-seropositive patients.


METHODS
--Nested case-control and cross-sectional analyses.


METHODS
--Community-based cohort of IVDUs.


METHODS
--Two hundred sixty HIV-1-seropositive and -seronegative IVDUs, drawn from an unselected cohort, were skin-tested for sensitivity to PPD tuberculin, mumps, and Candida antigens using the Mantoux method.


METHODS
--Positivity to PPD tuberculin, skin test anergy.


RESULTS
--Even using the CDC definition of an induration 5 mm or greater in diameter in HIV-1 seropositives, this group was substantially less likely to be PPD tuberculin positive than HIV-1 seronegatives (13.8% vs 25.2%; P = .02). In the HIV-1 seropositives the relative odds of being PPD positive varied depending on whether 10 mm or greater (odds ratio [OR], 0.3; 95% confidence interval [CI], 0.2 to 0.7), 5 mm or greater (OR, 0.5; 95% CI, 0.2 to 0.9), or 2 mm or greater (OR, 0.7; 95% CI, 0.4 to 1.3) was used to define a positive test result. The mean diameter induration in the HIV-1-seropositive group was 2.6 mm vs 5.4 mm in the seronegative group (P = .005). Skin test anergy (to mumps and Candida) appeared to explain the differential. Anergy was substantially higher in the HIV-1 seropositive group and increased as the CD4+ lymphocyte count fell (chi 2 for linear trend, 24.5; P less than .0001). An inverse linear trend for PPD positivity and CD4+ lymphocyte count was also observed (chi 2 for trend, 6.1; P = .01). In multivariate analyses, being 35 years of age or older and being HIV-1 seronegative were significantly associated with PPD positivity, while history of previous police arrest was of borderline significance. Only HIV-1 seropositivity was significantly associated with anergy.


CONCLUSIONS
--These findings show that CDC-recommended definition of an induration 5 mm or greater in diameter for PPD tuberculin positivity in HIV-1 seropositives significantly underestimates the "true" infection rate (using the PPD positivity rate in HIV-1 seronegatives as the criterion standard). A definition of 2 mm or greater would appear to be a better cutoff for reducing misclassification in HIV-1 seropositives. This study also confirms that delayed-type hypersensitivity is seriously depressed in HIV-1 seropositive IVDUs and that anergy testing is mandatory to properly assess a negative PPD test result.
Graham
N M
NM
Department of Epidemiology, Johns Hopkins Univesity School of Hygiene and Public Health, Baltimore, MD 21205.
Nelson
K E
KE
Solomon
L
L
Bonds
M
M
Rizzo
R T
RT
Scavotto
J
J
Astemborski
J
J
Vlahov
D
D
D000293:Adolescent; D000328:Adult; D002177:Candidiasis / Q000175:diagnosis / Q000276:immunology; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006679:HIV Seropositivity / Q000150:complications / Q000276:immunology*; D015497:HIV-1; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009107:Mumps / Q000175:diagnosis / Q000276:immunology; D015995:Prevalence; D012882:Skin Tests; D015819:Substance Abuse, Intravenous / Q000150:complications / Q000276:immunology*; D014374:Tuberculin Test; D014376:Tuberculosis / Q000150:complications / Q000175:diagnosis*