Table of Contents
ISRN Pharmacology
Volume 2012, Article ID 274978, 7 pages
http://dx.doi.org/10.5402/2012/274978
Research Article

Plasma Drug Level Validates Self-Reported Adherence but Predicts Limited Specificity for Nonadherence to Antiretroviral Therapy

1Department of Pharmacology and Therapeutics, School of Biomedical Sciences, College of Health Sciences, Makerere University, P.O. Box 7072, Kampala, Uganda
2Data Department, Joint Clinical Research Centre, P.O. Box 10005, Kampala, Uganda
3Department of Pharmacology and Therapeutics, Gulu University, P.O. Box 166, Gulu, Uganda
4Department of Chemistry, School of Physical Sciences, College of Natural Sciences, Makerere University, P.O. Box 7072, Kampala, Uganda
5Clinical Epidemiology Unit, School of Medicine, College of Health Sciences, Makerere University, P.O. Box 7072, Kampala, Uganda

Received 21 November 2011; Accepted 20 December 2011

Academic Editors: G. Hempel, D. K. Miller, and K. Wada

Copyright © 2012 Robert Balikuddembe et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Introduction. Adherence to antiretroviral therapy (ART) in low-income countries is mainly assessed by self-reported adherence (S-RA) without drug level determination. Nonadherence is an important factor in the emergence of resistance to ART, presenting a need for drug level determination. Objective. We set out to establish the relationship between plasma stavudine levels and S-RA and validate S-RA against the actual plasma drug concentrations. Methods. A cross-sectional investigation involving 234 patients in Uganda. Stavudine plasma levels were determined using high-performance liquid chromatography. We compared categories of plasma levels of stavudine with S-RA using multivariable logistic regression models. Results. Overall, 194/234 patients had S-RA ≥ 95% (good adherence) and 166/234 had stavudine plasma concentrations ≥ 36 nmol/L (therapeuticconcentration). Patients with good S-RA were eight times more likely to have stavudine levels within therapeutic concentration (Adjusted Odds Ratio: 7.7, 95% Confidence Interval: 3.5–7.0). However, of the 194 patients with good S-RA, 21.7% had below therapeutic concentrations. S-RA had high sensitivity for adherence (91.6%), but limited specificity for intrinsic poor adherence (38.2%). Conclusions. S-RA is a good tool for assessing adherence, but has low specificity in detecting nonadherence, which has implications for emergence of resistance.