The importance of social support and food insecurity in improving outcomes for perinatal depression: A causal mediation analysis of the AFFIRM-SA trial.

BACKGROUND

Understanding the mechanisms through which psychological interventions influence symptoms of perinatal depression can inform the development of interventions for improving maternal mental health. The AFFIRM-SA trial, conducted in an underserved settlement on the outskirts of Cape Town, was a task-shared psychological intervention designed to improve symptoms of perinatal depression. We aim to estimate indirect effects of mediators through which the AFFIRM-SA intervention reduced perinatal depressive symptoms.

METHODS

Interventional Effects, a robust causal inference framework, was used to decompose the total effect of randomisation to the intervention on symptoms of perinatal depression reducing by at least 40 % on the Edinburgh Postnatal Depression Scale (EPDS) at 12 months postpartum in women with complete data (n = 310), into the following indirect effects at three months postpartum: experienced violence, presence of moderate or severe levels of food, and mean levels of perceived social support.

RESULTS

Of the total effect of the intervention measured through the difference in EPDS scores improving by at least 40 % between treatment arms (mean difference in probability between intervention and control arm: 0.139, bias-corrected 95 % CI -0.056 to 0.224), 8 % was mediated through reduced levels of severe food insecurity (0.011; bias-corrected 95 % CI 0.003, 0.029) and 9 % through increased levels of perceived social support (0.012: bias-corrected 95 % CI: 0.001, 0.032). There was no evidence to support the mediating role of reduced levels of violence.

LIMITATIONS: The main limitation is the sample size (n = 310) which reduces the certainty of our findings where mediators are uncommon (e.g., domestic violence).

CONCLUSIONS

Our findings suggest that psychological interventions that combine psychological components with interventions that directly target social determinants of mental health (such as food insecurity and social support) could substantially improve perinatal depression.