Appropriateness of antidepressant prescribing: an observational study in a Scottish primary-care setting

Background Since the 1990s, Scottish community-based antidepressant prescribing has increased substantially.

Aim To assess whether GPs prescribe antidepressants appropriately.

Design of study Observational study of adults (aged >= 16 years) screened with the Hospital Anxiety and Depression Scale (HADS) attending a GP.

Setting Four practices in Grampian, Scotland.

Method Patients (n = 898) completed the HADS, and GPs independently estimated depression status. Notes were scrutinised for evidence of antidepressant use, and the appropriateness of prescribing was assessed.

Results A total of 237 (26%) participants had HADS scores indicating 'possible'(15%) or 'probable'(11%) depression. The proportion of participants rated as depressed by their GP differed significantly by HADS depression subscale scores. Odds ratio for 'possible' versus 'no' depression was 3.54 (95% confidence interval [CI] = 2.17 to 5.76, P<0.001); and for 'probable' versus 'possible' depression was 3.59 (95% CI = 2.06 to 6.26, P<0.001). Similarly, the proportion of participants receiving antidepressants differed significantly by HADS score. Odds ratio for 'possible' versus 'no' depression was 2.79 (95% Cl = 1.70 to 4.58, P<0.001); and for 'probable' versus 'possible' was 2.12 (95% Cl = 1.21 to 3.70, P = 0.009). In 101 participants with 'probable' depression, GPs recognised 53 (52%) participants as having a clinically significant depression. Inappropriate initiation of antidepressant treatment occurred very infrequently. Prescribing to participants who were not symptomatic was accounted for by the treatment of pain, anxiety, or relapse prevention, and for ongoing treatment of previously identified depression.

Conclusion There was little evidence of prescribing without relevant indication. Around half of patients with significant symptoms were not identified by their GP as suffering from a depressive disorder: this varied inversely with severity ratings. Rather than prescribing indiscriminately (as has been widely assumed), it is likely that GPs are initiating antidepressant treatment conservatively.