Predictability of the one-year course of depression and generalized anxiety in primary care

Several predictors of the course of depression and generalized anxiety have been identified. Whether these predictors provide a solid basis for primary care physicians (PCPs) to give an accurate prognosis remains unclear. A parallel study showed modest agreement between PCP prognosis and observed course (kappa< or = 0.21). It is the aim of the present study to establish the extent to which the one-year course of depression and generalized anxiety in primary care is in fact predictable. Predictability is operationalized as the combined predictive power of major prognostic factors identified in the literature. We identified 269 cases of ICD-10 depression and 134 of generalized anxiety among consecutive PCP attenders. For these patients a statistical model was built that provided optimal predictions of the one-year course of the disorder, based on the prognostic factors discerned. The predictions were compared with the actual course observed. Reasonable agreement (kappa = 0.37 for depression, kappa = 0.35 for anxiety) and good association (gamma = 0.66 for depression, gamma=0.67 for anxiety) were found between predicted and observed course. Nevertheless, the combined predictive power of the prognostic factors remains limited. A realistic evaluation of the accuracy of the PCP prognosis should take this limited predictability into account.