Socioeconomic factors explain suboptimal adherence to antiretroviral therapy among HIV-infected Australian adults with viral suppression

BACKGROUND: Missing more than one tablet of contemporary antiretroviral therapy (ART) per month increases the risk of virological failure. Recent studies evaluating a comprehensive range of potential risk factors for suboptimal adherence are not available for high-income settings.

METHODS: Adults on ART with undetectable viral load (UDVL) were recruited into a national, multi-centre cohort, completing a comprehensive survey assessing demographics, socio-economic indicators, physical health, well-being, life stressors, social supports, HIV disclosure, HIV-related stigma and discrimination, healthcare access, ART regimen, adherence, side effects, costs and treatment beliefs. Baseline data were assessed, and suboptimal adherence was defined as self-reported missing ≥1 ART dose/month over the previous 3-months; associated factors were identified using bivariate and multivariate binary logistic regression.

RESULTS: We assessed 522 participants (494 [94.5%] men, mean age = 50.8 years, median duration UDVL = 3.3 years [IQR = 1.2-6.8]) at 17 sexual health, hospital, and general practice clinics across Australia. Seventy-eight participants (14.9%) reported missing ≥1 dose/month over the previous three months, which was independently associated with: being Australian-born (AOR [adjusted odds ratio] = 2.4 [95%CI = 1.2-4.9], p = 0.014), not being in a relationship (AOR = 3.3 [95%CI = 1.5-7.3], p = 0.004), reaching the "Medicare safety net" (capping annual medical/pharmaceutical costs) (AOR = 2.2 [95%CI = 1.1-4.5], p = 0.024), living in subsidised housing (AOR = 2.5 [95%CI = 1.0-6.2], p = 0.045), receiving home-care services (AOR = 4.4 [95%CI = 1.0-18.8], p = 0.046), HIV community/outreach services linkage (AOR = 2.4 [95%CI = 1.1-5.4], p = 0.033), and starting ART following self-request (AOR = 3.0 [95%CI = 1.3-7.0], p = 0.012).

CONCLUSIONS: In this population, 15% reported recent suboptimal ART adherence at levels associated in prospective studies with subsequent virological failure, despite all having an undetectable viral load. Associations were with social/economic/cultural/patient engagement factors, but not ART regimen/clinical factors. These associations may help identify those at higher risk of future virological failure and guide patient education and support.