Predictive values of prurigo nodularis and herpes zoster for HIV infection and immunosuppression requiring HAART in French Guiana

Prurigo nodularis and herpes zoster frequently lead to the diagnosis of HIV in tropical areas. The WHO has established a clinical definition of AIDS for undeveloped countries. Prurigo and herpes zoster are both classified as stage 2. The main objective of this study was to compare the level of immunosuppression of patients diagnosed as HIV-positive after consulting for prurigo nodularis or herpes zoster in French Guiana. A retrospective study was conducted including patients consulting at the Department of Dermatology, Cayenne Hospital (French Guiana) for prurigo nodularis or herpes zoster between 1989 and 2007 for which the systematic HIV test was positive. Demographic data and CD4 counts of both groups were compared. Analysis of 346 patients consulting for herpes zoster (n = 192) or prurigo nodularis (n = 154) led to the discovery of 129 HIV infections. The positive predictive value (PPV) for HIV positivity was 38.5% for herpes zoster and 36% for prurigo nodularis. The median lymphocyte count was 302/mm3 in herpes zoster and 87/mm3 in prurigo nodularis (P < 0.001). The PPV for having a CD4 lymphocyte count < 200/mm3 was 26.5% for herpes zoster and 72% for prurigo nodularis. Prurigo nodularis was predictive of advanced immunosuppression. This questions the pertinence of the WHO clinical classification of AIDS. In the absence of CD4 count, the present results suggest that for patients with prurigo nodularis, antiretrovirals should be initiated without delay.