CD4+ cell count and risk for antiretroviral drug resistance among women using peripartum nevirapine for perinatal HIV prevention.

OBJECTIVE

To determine the association between the antenatal CD4(+) cell count and the development of viral drug resistance following the use of peripartum nevirapine (NVP) for perinatal HIV prevention.

DESIGN

Secondary analysis of data from a previously conducted randomised controlled trial.

SETTING

Lusaka, Zambia.

POPULATION

HIV-positive pregnant women.

METHODS

We analysed the data from a clinical trial of single-dose tenofovir/emtricitabine (TDF/FTC) to reduce viral drug resistance associated with peripartum NVP. The trial population was categorised according to antenatal CD4(+) cell count (200-350, 351-500 and >500 cells/μl).

MAIN OUTCOME MEASURES

The relative risk for acquiring drug resistance, determined by consensus sequencing and oligonucleotide ligation assay (OLA), was estimated using multivariable logistic regression.

RESULTS

Of the 397 study participants, 119 (30%) had a CD4(+) count of 200-350 cells/μl, 135 (34%) had a CD4(+) count of 351-500 cells/μl and 143 (36%) had a CD4(+) count of >500 cells/μl. Among women receiving no intervention, the risk for drug resistance appeared to increase as the CD4(+) cell count decreased. Participants with CD4(+) cell counts of 200-350 cells/μl randomised to the study arm had the lowest risk, suggesting a higher efficacy of the intervention within this stratum. These results were consistent at 2 and 6 weeks, regardless of how drug resistance was measured.

CONCLUSIONS

Women with CD4(+) cell counts of 200-350 cells/μl may be at increased risk for viral drug resistance following the use of peripartum NVP. Given the high prevalence of NVP resistance and the clear benefits of treatment, antiretroviral therapy should be initiated among pregnant women with CD4(+) cell counts of ≤350 cells/μl.