M Derisi and a research group from the Univ. of Cal.- San Diego Medical Center (Owen Clinic) reported this study. The aim of this study was to identify risk factors for NNRTI-associated rash in a clin. care population.

Nevirapine (NVP), delavirdine (DLV), and efavirenz (EFV) were associated with rash in 18-37% of patients in clinical trials. Trimethoprim/ sulfamethoxazole (TMP/SMX) induces a clinically similar rash, occurring about ten times as often among HIV-infected patients than among uninfected patients.

Authors conducted a retrospective analysis of a clinical cohort initiating or changing antiretroviral therapy with a NNRTI-containing regimen between June 1996 and April 1999. Demographic and clinical characteristics, including prior sulfa exposure and subsequent presence or absence of rash were examined as potential risk factors for NNRTI-associated rash using logistic regression.

436 patients met inclusion criteria. Patient characteristics included: 87% male; by race, 14% African-American, 21% Hispanic, 60% Caucasion, 5% other; median (range) CD4+ lymphocyte count 173 (0-1101); by NNRTI exposure, 50% NVP, 44% EFV, 6% DLV. The prevalence of NNRTI-associated rash varied from 8.4% (EFV) to 14.4% (NVP) (p=0.17). According to prior sulfa experience, the incidence of NNRTI-associated rash increased from 5% (prior sulfa and no rash), to 13% (no prior sulfa exposure), to 28% (prior sulfa and rash) (p<0.0001). By race, the incidence of NNRTI rash varied from 6% in African-American patients to 20% in Hispanic patients (p=0.028). Among those with prior sulfa exposure (n=373), in a multiple logistic regression model, prior sulfa rash and Hispanic descent were independent risk factors for NNRTI rash; odds ratios were 8 (95% CI 3.8-16.9) and 2.6 (95% CI 1.2-5.8), respectively.

The incidence of NNRTI-associated rash is significantly influenced by sulfa history and Hispanic race. Gender, CD4 count, and choice of NNRTI were not found to be significant predictors.