Illness beliefs about depression among patients seeking depression care and patients seeking cardiac care: an exploratory analysis using a mixed method design.

Background: Treatment of depression in cardiac patients is difficult. Patients' illness beliefs regarding depression are associated with outcomes. The aim of the mixed-methods study was to test whether patients in routine care for depression differ from patients with depression in routine care for cardiac diseases regarding illness beliefs about depression.

Methods: A consecutive sample of n = 217 patients with depressive disorder was recruited from routine care for depression (N = 148) and routine care for cardiac diseases (N = 69). Beliefs about depression were measured by the Brief-Illness Perception Questionnaire. Causal beliefs were categorized using qualitative methods. To investigate differences regarding other illness beliefs, we performed an ANCOVA controlling for sociodemographic and clinical differences by propensity score matching.

Results: Patients in routine care for cardiac diseases attributed their depression more often to physical illnesses (48% vs. 16%) and less often to their self (30% vs. 47%), problems at work (25% vs. 35%), childhood (25% vs. 30%), and negative life events (19% vs. 25%) in contrast to patients in routine care for depression. Patients in routine care for cardiac diseases reported beliefs of lower disability, burden, and treatment-control and of higher self-control in contrast to patients in routine care for depression.

Conclusions: Illness beliefs especially causal beliefs differ between patients in routine care for cardiac diseases and routine care for depression. Future research should investigate effects of these illness beliefs. We recommend exploring patients' illness beliefs about depression in routine care for cardiac diseases and routine care for depression.