Research paperImpact of functional and structural social relationships on two year depression outcomes: A multivariate analysis

•Patients with depressive symptoms and poor quality relationships are at risk of persistent depression.•Subjective social relationships had a stronger role in predicting depression outcomes than physical comorbidity, economic disadvantage or alcohol abuse.Subjective social relationships independently predicted depression course even when childhood trauma, personality and baseline depression was accounted for.•People with depressive symptoms and poor quality relationships may benefit from personalised treatment and relapse prevention strategies adapted to focus on social relationships.

BackgroundHigh rates of persistent depression highlight the need to identify the risk factors associated with poor depression outcomes and to provide targeted interventions to people at high risk. Although social relationships have been implicated in depression course, interventions targeting social relationships have been disappointing. Possibly, interventions have targeted the wrong elements of relationships. Alternatively, the statistical association between relationships and depression course is not causal, but due to shared variance with other factors. We investigated whether elements of social relationships predict major depressive episode (MDE) when multiple relevant variables are considered.MethodData is from a longitudinal study of primary care patients with depressive symptoms. 494 participants completed questionnaires at baseline and a depression measure (PHQ-9) two years later. Baseline measures included functional (i.e. quality) and structural (i.e. quantity) social relationships, depression, neuroticism, chronic illness, alcohol abuse, childhood abuse, partner violence and sociodemographic characteristics. Logistic regression with generalised estimating equations was used to estimate the association between social relationships and MDE.ResultsBoth functional and structural social relationships predicted MDE in univariate analysis. Only functional social relationships remained significant in multivariate analysis (OR: 0.87; 95%CI: 0.79-0.97; p=0.01). Other unique predictors of MDE were baseline depression severity, neuroticism, childhood sexual abuse and intimate partner violence.LimitationsWe did not assess how a person's position in their depression trajectory influenced the association between social relationships and depression.ConclusionsInterventions targeting relationship quality may be part of a personalised treatment plan for people at high risk due of persistent depression due to poor social relationships.