Predicting factors for unsuccessful switching from nevirapine to efavirenz in HIV-infected patients who developed nevirapine-associated skin rash.

Skin rash associated with nevirapine (NVP) is common and efavirenz (EFV) is often used as a substitute. We aimed to determine the predicting factors for unsuccessful switching from NVP to EFV. A retrospective cohort study was conducted in HIV-infected patients who developed rash after taking NVP. There were 109 patients with a mean standard deviation (SD) age of 36.6 (7.4) years and 45% were males. Median (interquartile range) CD4 cell count and HIV RNA at the time of NVP initiation were 163 (50-273) cells/mm(3) and 4.6 (1.7-5.4) log copies/mL, respectively. Twenty (18.3%) patients subsequently developed EFV-associated rash. By logistic regression, history of drug allergy apart from NVP (odds ratio [OR] 11.42) and CD4 cell count <100 cells/mm(3) (OR 6.14) were significant predicting factors for EFV-associated rash. Two predicting factors for unsuccessful switching from NVP to EFV were found. Patients who have these factors need to have a close follow-up if EFV is substituted.