Response to Efavirenz-Containing Regimens in Previously Antiretroviral-Naive HIV-Positive Patients

BACKGROUND: We investigated the role of gender on response to efavirenz (EFV)-containing regimens in previously antiretroviral-naive patients. METHODS: All previously antiretroviral-naive individuals from the Royal Free Hospital in London starting EFV from 1996 onward were included. Treatment failure was defined as the first of 2 consecutive viral load measurements >500 copies/mL more than 24 weeks after starting EFV. Standard survival methods were used to assess time to discontinuation and to treatment failure. RESULTS: Ninety-six women and 337 men were included. Women were mostly of black African ethnicity (64.6%) with a heterosexual risk (94.8%), whereas men were mostly white (66.8%; P < 0.0001) with a homosexual risk (71.2%; P < 0.0001). Women had lower CD4 counts when starting EFV (median [interquartile range [IQR] = 126 [36, 220] cells/mm for women vs. 190 [109, 268] cells/mm for men; P = 0.0003). After 48 and 96 weeks, 38.8% (95% confidence interval [CI]: 28.8% to 48.7%) and 56.3% (95% CI: 45.8% to 66.9%) of women had discontinued EFV compared with 28.3% (95% CI: 23.4% to 33.2%) and 41.8% (95% CI: 36.3% to 47.3%) of men (P = 0.005). The percentage experiencing failure by 48 and 96 weeks when ignoring treatment changes but censoring at the date of discontinuing all treatment was 1.3% (0.0%, 3.9%) and 4.4% (0.0%, 9.3%) for women compared with 3.8% (1.6%, 6.0%; P = 0.49) and 5.8% (3.0%, 8.6%) for men. Median (IQR) CD4 count increases at 48 weeks were +166 (+89, +239) cells/mm for women and +176 (+93, +263) cells/mm for men. CONCLUSIONS: Women seem to have comparable virologic and immunologic outcomes to first-line EFV-containing regimens compared with men, although they are more likely to discontinue the drug.