Diagnostic accuracy and treatment approach to depression in primary care: predictive factors.

Objective: The study assessed the predictive factors of diagnostic accuracy and treatment approach (antidepressants versus active monitoring) for depression in primary care.

Methods: This is a cross-sectional study that uses information from a naturalistic prospective controlled trial performed in Barcelona (Spain) enrolling newly diagnosed patients with mild to moderate depression by GPs. Treatment approach was based on clinical judgement. Diagnosis was later assessed according to DSM-IV criteria using Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) interview by an external researcher. Patients (sociodemographic, psychiatric diagnosis, severity of depression and anxiety, health-related quality of life, disability, beliefs about medication and illness and comorbidities) and GP factors associated with diagnostic accuracy and treatment approach were assessed using multilevel logistic regression. Variables with missing data were imputed through multiple imputations.

Results: Two hundred sixty-three patients were recruited by 53 GPs. Mean age was 51 years (SD = 15). Thirty percent met DSM-IV criteria for major depression. Mean depression symptomatology was moderate-severe. Using multivariate analyses, patients' beliefs about medicines were the only variable associated with the antidepressant approach. Specialization in general medicine and being a resident tutor were associated with a more accurate diagnosis.

Conclusions: Clinical depression diagnosis by GPs was not always associated with a formal diagnosis through a SCID-I. GPs' training background was central to an adequate depression diagnosis. Patients' beliefs in medication were the only factor associated with treatment approach. More resources should be allocated to improving the diagnosis of depression.