Increasing body mass index or weight does not appear to influence the association between efavirenz-based antiretroviral therapy and implant effectiveness among HIV-positive women in western Kenya

Abstract Objective Our objective was to evaluate if increasing body mass index (BMI) or weight influences the association between efavirenz-based antiretroviral therapy (ART) and implant effectiveness. Study design We conducted a secondary cohort analysis of HIV-positive women aged 15 to 45 years enrolled in HIV care in western Kenya using an implant from January 2011 to December 2015. Implant use, ART regimen, and weight were documented at each clinic visit and height at enrollment. We categorized BMI as underweight, normal weight, overweight, or obese, and weight as Results In this analysis, 12,960 women contributed a total of 11,285 woman-years (w-y) of observation time while using an implant, with a median of 6.6 months. The aIRRs comparing efavirenz- to nevirapine-based ART groups did not increase as BMI increased; the aIRRs were 2.0 (1.1–3.6) for underweight, 1.9 (1.5–2.5) for normal, 3.1 (1.6–6.0) for overweight, and 2.1 (0.6–6.9) for obese women. The aIRRs comparing efavirenz- to nevirapine-based ART groups did not increase as weight increased; the aIRRs were 2.0 (1.6–2.6) for weight Conclusion Higher BMI or weight did not appear to modify the relationship between efavirenz use and implant effectiveness. Implications. Programs should not recommend differential counseling for women with higher BMI or weight who concomitantly use implants and efavirenz.