Relationship between antidepressant and anxiolytic/hypnotic prescribing: a mixed-methods study.

Background: Antidepressant prescribing has dramatically increased in Scotland, and the cause is unknown.

Objective: To investigate if the increase in antidepressant prescribing coincided with a reduction in prescribing of anxiolytics and hypnotics; to investigate this relationship at practice level; and to explore whether general practitioners (GPs) explain the increase by their increased use for anxiety.

Study Design: analysis of routine prescribing data and interviews with GPs.

Setting: Scottish general practices.

Participants: 942 practices included in the analysis. Sixty-three GPs in 30 practices completed interviews.

Main Outcome Measures: Quantity of antidepressants, anxiolytics, and hypnotics prescribed. Relationship at practice level between anxiolytic/hypnotic and antidepressant prescribing. Spontaneous comments by GPs about prescribing antidepressants for anxiety.

Results: Antidepressant prescribing increased from 28.9 million defined daily doses (DDDs) in 1992/3 to 128.3 million in 2004/5. Anxiolytic/hypnotic prescribing fell from 64.2 million to 55.1 million DDDs. There was a weak, positive correlation between levels of antidepressant and anxiolytic/hypnotic prescribing (+0.084, p=0.010). GPs treated anxiety with antidepressants, although many described an overlap between anxiety and depression. Some spontaneously identified a relationship with benzodiazepine prescribing when asked to explain the increase in antidepressant prescribing.

Conclusion: A small part of the increase in antidepressant prescribing is due to substitution for benzodiazepines to treat anxiety.