Predictors of incident major depression in diabetic outpatients with subthreshold depression

Aims: The objective of the study was to determine rates and risks of major depression in diabetes outpatients with subthreshold depression.

Methods: This study is based on data of a stepped care-based intervention study in which diabetic patients with subthreshold depression were randomly allocated to low-intensity stepped care, aimed at reducing depressive symptoms, or to care as usual. Patients had a baseline Center for Epidemiologic Studies Depression Scale (CES-D) score ≥ 16, but no baseline major depression according to the Mini International Neuropsychiatric Interview (MINI). Demographic, biological and psychological characteristics were collected at baseline. The MINI was used to determine whether participants had major depression during 2-year follow-up. Predictors of major depression were studied using logistic regression models.

Results: Of the 114 patients included at baseline, 73 patients were available at 2-year follow-up. The 2-year incidence of major depression was 42% (n=31). Higher baseline anxiety levels [odds ratio (OR)=1.25; 95% confidence interval (CI), 1.04-1.50; P=0.018] and depression severity levels (OR=1.09; 95% CI, 1.00-1.18; P=0.045) were predictors of incident major depression. Stepped care allocation was not related to incident major depression. In multivariable models, similar results were found.

Conclusions: Having a higher baseline level of anxiety and depression appeared to be related to incident major depression during 2-year follow-up in diabetic patients with subthreshold depression. A stepped care intervention aimed at depression alone did not prevent the onset of depression in these patients. Besides level of depression, anxiety might be taken into account in the prevention of major depression in diabetic patients with subthreshold depression.