Objective: To determine if general practitioner rates of antidepressant drug prescribing and referrals to specialist services for depression vary in line with patients' scores on depression severity questionnaires.
Design: Analysis of anonymised medical record data.
Setting: 38 general practices in three sites-Southampton, Liverpool, and Norfolk. Data reviewed Records for 2294 patients assessed with severity questionnaires for depression between April 2006 and March 2007 inclusive.
Main outcome measures: Rates of prescribing of antidepressants and referrals to specialist mental health or social services.
Results: 1658 patients were assessed with the 9 item patient health questionnaire (PHQ-9), 584 with the depression subscale of the hospital anxiety and depression scale (HADS), and 52 with the Beck depression inventory, 2nd edition (BDI-II). Overall, 79.1% of patients assessed with either PHQ-9 or HADS received a prescription for an antidepressant, and 22.8% were referred to specialist services. Prescriptions and referrals were significantly associated with higher severity scores. However, overall rates of treatment and referral were similar for patients assessed with either measure despite the fact that, with PHQ-9, 83.5% of patients were classified as moderately to severely depressed and in need of treatment, whereas only 55.6% of patients were so classified with HADS. Rates of treatment were lower for older patients and for patients with comorbid physical illness (including coronary heart disease and diabetes) despite the fact that screening for depression among such patients is encouraged in the quality and outcomes framework. Conclusions General practitioners do not decide on drug treatment or referral for depression on the basis of questionnaire scores alone, but also take account of other factors such as age and physical illness. The two most widely used severity questionnaires perform inconsistently in practice, suggesting that changing the recommended threshold scores for intervention might make the measures more valid, more consistent with practitioners' clinical judgment, and more acceptable to practitioners as a way of classifying patients.