Predictors of adherence to antiretroviral therapy in rural Zambia

Abstract

Background/objective: Antiretroviral therapy (ART) adherence levels of >or=95% optimize outcomes and minimize HIV drug resistance. As such, identifying barriers to adherence is essential. We sought to assess travel to point-of-care for ART as a potential barrier to adherence in rural Zambia, within the context of patient demographics, perceived stigma, and selected clinical indices.

Methods: We studied 424 patients receiving ART from the Macha Mission Hospital (MMH). Interviews ascertained age, gender, education, perceived stigma, nearest rural health facility (RHF), and mode/cost/time of transport for each study participant. Motorcycle odometer and global positioning system way-points measured distance from the MMH to each of the RHFs, estimating patients' home-to-MMH travel distances. Body mass index, World Health Organization HIV/AIDS stage, and pill counts were assessed from review of patients' medical and pharmacy records.

Results: At least 95% adherence was documented for 83.7% of the patients in their first months of ART. Travel-related factors did not predict adherence. Adherence was higher for those on ART for a longer time (odds ratio = 1.04 per day; P = 0.002).

Conclusions: Patients in rural Zambia can achieve adherence rates compatible with good clinical outcomes despite long travel distances. The MMH was able to provide quality HIV/AIDS care by implementing programmatic features selecting for a highly adherent population in this resource-limited setting.

FIGURE 1

Volunteers and population of origin for the rural Zambian study of predictors of adherence to ART (final study: n = 409).

FIGURE 2

Form used to calculate patient adherence. The form utilizes pill counts (A and G) and pharmacy records (B) to determine the percentage of doses taken out of the number of doses prescribed for a given interval of time for a particular drug regimen. The lowest adherence percentage calculated for a single review was considered as a conservative estimate of a patient’s overall adherence. In this example, adherence was calculated for a 30-day period between clinic visits, and overall adherence for this period would be considered 70%. NVP indicates nevirapine; 3TC, lamivudine; ZDV, zidovudine.

FIGURE 3

The number of patients per RHF per chiefdom. The map was created from GPS way-points of RHFs nearest to patients’ homes, as indicated by patient interviews.

FIGURE 4

Odds of adherence across the total days over which pill counts were measured (days on ART), adjusted for home-to-MMH travel time, WHO stage, BMI, perceived stigma, and cost of transportation at their median values.