To the Editor:
I would like to compliment Eholié and colleagues on their report “Field Adherence to Highly Active Antiretroviral Therapy in HIV-Infected Adults in Abidjan, Cote d'Ivoire.”1 This manuscript is instructive because it is one of the few reports that find less-than-exceptional levels of adherence to HIV antiretroviral therapy in sub-Saharan Africa. In this study of 308 individuals on partially subsidized antiretrovirals, mean adherence was 78%, a level of adherence comparable to what is currently seen in North America and Western Europe.2 The most commonly reported barrier to adherence in this study was pharmacy stock-outs (28%). Financial demands of securing partially subsidized antiretroviral medications was also a common reason for missing doses (20%). These findings are similar to other studies reporting that financial barriers to access-either costs associated with transport to clinic, the cost of medications themselves, or pharmacy stock-outs3-7-are among the most frequent causes of missed doses in resource-limited settings.
These structural causes of missed doses call for a more precise use of the term “adherence.” Adherence is defined as “taking medication as prescribed” and presumes access to medication. Failure to access therapy and failure to adhere to therapy require different responses. The former calls for stable drug supply and distribution, whereas the latter calls for interventions to sustain individual behavior. It is impossible to adhere to medications without access.
These concepts also have different implications with respect to the risk of resistance. Pharmacy stock-outs and failure to secure financial resources to pick up refills lead to interrupted therapy at the individual level, but also potentially across entire systems of care. Sustained and repeated interruptions pose a greater risk than the occasional missed dose for resistance to nonnucleoside reverse transcriptase inhibitor-based therapy, the mainstay of treatment in resource-limited settings.7,8 The article by Eholié et al highlights that these structural barriers to access are the true Achilles' heel of therapy in resource-limited settings.
David R. Bangsberg, MD, MPH
Epidemiology and Prevention Interventions Center Division of Infectious Diseases The Positive Health Program San Francisco General Hospital University of California, San Francisco San Francisco, CA
1. Eholie SP, Tanon A, Polneau S, et al. Field adherence to highly active antiretroviral therapy in HIV-infected adults in Abidjan, Cote d'Ivoire. J Acquir Immune Defic Syndr
2. Bangsberg DR, Deeks SG. Is average adherence to HIV antiretroviral therapy enough? J Gen Intern Med
3. Akam A. Anti-retroviral adherence in a resource poor setting [abstract]. Presented at: International AIDS Conference; 2004; Bangkok.
4. Hardon AP, Akurut D, Comoro C, et al. Hunger, waiting time and transport costs: time to confront challenges to ART adherence in Africa. AIDS Care
5. Byakika-Tusiime J, Oyugi JH, Tumwikirize WA, et al. Adherence to HIV antiretroviral therapy in HIV+ Ugandan patients purchasing therapy. Int J STD AIDS
6. Weiser S, Wolfe W, Bangsberg D, et al. Barriers to antiretroviral adherence for patients living with HIV infection and AIDS in Botswana. J Acquir Immune Defic Syndr
7. Oyugi JH, Byakika-Tusiime J, Ragland K, et al. Treatment interruptions predict resistance in HIV-positive individuals purchasing fixed-dose combination antiretroviral therapy in Kampala, Uganda. AIDS
8. Parienti J, Massari V, Descamps D, et al. Predictors of virologic failure and resistance in HIV-infected patients treated with nevirapine- or efavirenz-based antiretroviral therapy. Clin Infect Dis