Background: Measurement of adherence to antiretroviral therapy (ART) by patient self-report is common in resource-limited settings but widely believed to overstate actual adherence. The extent to which these measures overstate adherence has not been examined among a large patient population.
Methods: HIV-infected adult patients in Kenya who initiated ART within the past 3 months were followed for 6 months. Adherence was measured by participants’ self-reports of doses missed in the past 7 days during monthly clinic visits and by continuous Medication Event Monitoring System (MEMS) in participants’ pill bottles. Seven-day self-reported adherence was compared to 7-day MEMS adherence, 30-day MEMS adherence, and adherence more than 90% during each of the first 6 months.
Results: Self-reported and MEMS adherence measures were linked for 669 participants. Mean 7-day self-reported adherence was 98.7% and mean 7-day MEMS adherence was 86.0%, a difference of 12.7% (P < 0.01). The difference between the two adherence measures increased over time due to a decline in 7-day MEMS adherence. However, patients with lower MEMS adherence were in fact more likely to self-report missed doses and the difference between self-reported and MEMS adherence was similar for each number of self-reported missed doses. When analysis was limited to patients who reported rarely or never removing multiple doses at the same time, mean difference was 10.5% (P < 0.01).
Conclusion: There is a sizable and significant difference between self-reported and MEMS adherence. However, a strong relationship between the measures suggests that self-reported adherence is informative for clinical monitoring and program evaluation.
aDepartment of Health Policy and Management, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
bDepartment of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana
cSchool of International and Public Affairs, Columbia University, New York, New York
dGeorgetown Public Policy Institute, Georgetown University, Washington, DC
eIndiana University School of Medicine, Indianapolis, Indiana, USA
fMoi University School of Medicine, Eldoret, Kenya
gMGH Center for Global Health
hHarvard Medical School
iRagon Institute of MGH, MIT and Harvard, Boston, Massachusetts, USA.
Correspondence to Harsha Thirumurthy, Department of Health Policy and Management, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Campus Box 7411, Chapel Hill, NC 27599-7411, USA. E-mail: email@example.com
Received 5 June, 2012
Revised 11 August, 2012
Accepted 23 August, 2012