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Determinants of Adherence to Antiretroviral Therapy Differ Between Africa and Asia
Rimke Bijker1, Awachana Jiamsakul2, Margaret Siwale3, Sasisopin Kiertiburanakul4, Cissy M. Kityo5, Praphan Phanuphak6, Tobias F. Rinke de Wit1, Oon Tek Ng7, Raph L. Hamers1, PASER-TASER Cohort Collaboration1
1 Department of Global Health, Academic Medical Center of the University of Amsterdam, Amsterdam Institute for Global Health and Development, Amsterdam, Netherlands. 2 The Kirby Institute, Sydney, NSW, Australia. 3 Lusaka Trust Hospital, Lusaka, Zambia. 4 Ramathibodi Hospital, Mahidol University, Bangkok, Thailand. 5 Joint Clinical Research Centre, Kampala, Uganda. 6 HIV-NAT/Thai Red Cross AIDS Research Centre, Bangkok, Thailand. 7 Tan Tock Seng Hospital, Novena, Singapore.
Background: Adherence to antiretroviral therapy (ART) has been poorly studied among HIV-infected populations in resource-limited settings. We studied determinants of adherence in sub-Saharan Africa and Asia.
Methods: In a cohort collaboration in Africa (6 countries, 13 sites) and Asia (5 countries, 11 sites) adherence was assessed using the WHO-validated Adherence Visual Analogue Scale (VAS) at each clinic visit, during the first 24 (all sites) or 36 (15 sites) months of 1st-line ART. The main outcome was suboptimal mean adherence (SubAdh), defined as mean VAS<95% for each 6-month period. We used generalized estimating equations multivariable regression, adjusting for number of adherence assessments, site type and calendar year. Region-of-residence was assessed as a potential effect modifier.
Results: In the first 24 months of follow-up, 23,074 VAS assessments were performed in 3,913 participants; median per participant was 7 (IQR 6-8) in Africa (n=2,409) and 8 (IQR 5-9) in Asia (n=1,504). Of 12,889 mean adherence scores, 6.5% (832/12,889) were classified as SubAdh, with 7.3% (614/8,398) in Africa versus 4.9% (218/4491) in Asia (Chi2, p<0.001) (Figure). SubAdh was strongly associated with virological failure (≥400 c/mL) at month 12 and 24 (Chi2, p<0.001). In Africa (but not in Asia), factors associated with SubAdh were male sex (OR 1.4, 95%CI 1.1-1.6) and any concomitant medication (1.9, 1.2-3.1); attending a non-government facility (0.7, 0.5-0.9) and older age were associated with less SubAdh. In Asia, relative to heterosexuals, SubAdh was lower in men who have sex with men (0.5, 0.3-0.9) and higher in injecting drug users (3.5, 2.1-5.8). In both regions, longer ART duration (extending to at least 36 months) was associated with better adherence. A sensitivity analysis that accounted for attrition, using last observation carried forward methods, suggested that adherence improvement with ART duration was not entirely due to attrition bias or missing data. Type of ART regimen was not associated with SubAdh. Participants from high or upper-middle income countries had a 24% (95%CI 7-38%) reduced risk of SubAdh, compared to low or lower-middle income countries (p=0.007).
Conclusions: Cross-regional differences may be partly related to health system resources, although social desirability bias cannot be excluded. Interventions to improve adherence need to be locally tailored and should particularly target the first ART years.