What works and for whom in treating depression in older adults in deprived communities in Brazil: Findings from a causal mediation analyses of the PROACTIVE trial that overlapped with the COVID-19 pandemic

BackgroundThe PROACTIVE trial was a task-shared, collaborative care, psychosocial intervention that was highly effective at improving recovery from depression in older adults in Brazil that overlapped with the COVID-19 pandemic. Here we investigate mediators of the interventions effectiveness. MethodsCausal mediation analysis using interventional indirect effects, decomposed the total effect of PROACTIVE on recovery from depression (PHQ-9<10), into multiple indirect effects including: dose of intervention (number of sessions and number of activities completed); social support measured through Luben Social Network Scale; perceived loneliness through the three-item UCLA questionnaire; conditions associated with frailty; and extra sessions offered to participants who did not respond to the intervention. FindingsOf the interventions total effect (difference in probability of recovery from depression between the intervention and control arms 0{middle dot}211 [bias-corrected 95% CI: 0{middle dot}139, 0{middle dot}274]): 14% was mediated through improved conditions associated with frailty 0{middle dot}030 [0{middle dot}003, 0{middle dot}065]); 6% through reduced loneliness (0{middle dot}013 [0{middle dot}001, 0{middle dot}028]); and 20% through attending extra sessions for participants who did not respond to the intervention (0{middle dot}042 [0{middle dot}007, 0{middle dot}105]). InterpretationOur findings emphasise the importance of a home-based intervention to improve depression outcomes where participants are encouraged to self-select activities to mitigate against loneliness and are referred to primary care to manage health issues relating to frailty. Importantly, our findings suggest that offering extra sessions to participants who did not respond to the intervention shows promise in ensuring a sustained recovery from depression. FundingSao Paulo Research Foundation and Joint Global Health Trials UK.