Objective: We aimed to investigate potential causes of higher risk of treatment interruptions within the multicountry Strategic Timing of AntiRetroviral Treatment (START) trial in 2015.
Methods: We defined baseline as the date of starting antiretroviral therapy (ART) and a treatment interruption as discontinuing ART for at least 2 weeks. Participants were stratified by randomization arm and followed from baseline to earliest end date of the initial phase of START, death, date of consent withdrawn or date of first treatment interruption. Cox regression was used to calculate hazard ratios and 95% confidence intervals for factors that may predict treatment interruptions in each arm.
Results: Of the 3438 participants who started ART, 2286 were in the immediate arm and 1152 in the deferred arm. 12.9% of people in the immediate arm and 10.5% of people in the deferred arm experienced at least one treatment interruption by 3 years after starting ART. In adjusted analyses, age [hazard ratio for 35-50 years: 0.75 (95% confidence interval: 0.59-0.97) and >50 years: 0.53 (0.33-0.80) vs. <35 years], education status [hazard ratio for postgraduate education vs. less than high-school education (0.23 (0.10-0.50))] and region [hazard ratio for United States vs. Europe/Israel (3.16 (2.09-4.77))] were significantly associated with treatment interruptions in the immediate arm. In the deferred arm, age and education status were significantly associated with treatment interruptions.
Conclusion: Within START, we identified younger age and lower educational attainment as potential causes of ART interruption. There is a need to strengthen adherence advice and wider social support in younger people and those of lower education status.