Use of antidepressants by general practitioners and psychiatrists in Australia

Objective: To examine the antidepressant prescribing patterns of psychiatrists and general practitioners (GPs) in Australia, focusing specifically on: the prescribed daily dose, the relative proportions (from subsidized dispensing data) of prescriptions written, and how these proportions change over time for a newly listed antidepressant drug (using paroxetine as an example). Method: Retrospective analyses of subsidized claims data (comprising nearly 90% of the community supply of antidepressants) and prescriber surveys. Results: General practitioners prescribe 86% of subsidized antidepressants in Australia. Almost three-quarters of the antidepressant prescriptions prescribed in primary care management are also initiated by a GP. Psychiatrists prescribed higher doses than general practitioners for all the antidepressants examined. For paroxetine, a higher than average proportion of scripts were written by psychiatrists when the drug was initially available and it only reached the GP/psychiatrist split seen with an established drug in the same therapeutic class (fluoxetine) four years after marketing. The most prominent type of depression that GPs believed they were treating was 'chronic mild depression', which contrasts with the subsidized indication for all newer antidepressant classes of 'major depressive disorders'. Conclusions: General practitioners are the major providers of treatment for depression in Australia. When writing prescriptions for tricyclic antidepressants GPs use doses lower than those recommended for major depression, however, most management in primary care is not for conditions regarded by the GP as major depression. A significant number of prescriptions for the newer antidepressants may not accord with the Pharmaceutical Benefits Scheme (PBS) restrictions for use.