Explaining variation in antidepressant prescribing rates in east London: a cross sectional study.

BACKGROUND Rates of depression and anxiety in south Asian populations are lower than expected. It remains uncertain whether this reflects a real difference in prevalence or differences in case recognition and management. OBJECTIVE To examine whether concordance of culture or ethnicity between doctors and patients affects the prescribing rates for antidepressant and anxiolytic medications in general practice populations, taking into account demography, practice size and organization. METHOD A cross-sectional general practice study, using practice and demographic data from primary care trusts, doctors' place of qualification from the General Medical Council, combined with practice level prescribing data from the prescription pricing authority (PACT) for the period 2000-2002. Set in 139 practices in the east London primary care trusts (PCTs) of Tower Hamlets, Hackney and Newham, multiethnic areas with large populations of south Asian residents and doctors. The main outcome measure was the annual prescribing rates for each group of drugs, calculated as the mean of two years average daily quantities (ADQs) for each medication, divided by the practice population. RESULTS In east London the median prescribing rate (ADQs) for all antidepressants was 7.97 (inter-quartile range 4.91-10.76), for all anxiolytics and hypnotics 2.27 (interquartile range 1.11-3.96). There were significant differences in prescribing rates between practices with UK trained GPs and practices with south Asian trained GPs, with the highest rates of antidepressant prescribing in practices with UK trained GPs and low proportions of south Asian patients. No differences were found in anxiolytic and hypnotic prescribing rates between these practices. 57% of the variation in prescribing between practices could be explained by a model including the place of GP qualification, the proportion of registered women, older (>65) patients, and the list size per full time GP. CONCLUSIONS Compared with previous studies prescribing rates for antidepressants have almost doubled over five years, the greatest increase being for selective serotonin re-uptake inhibitors (SSRIs). There is a modest fall in prescribing rates for anxiolytics and hypnotics. Concordance between south Asian practice populations and doctors from similar south Asian cultures is not associated with an increase in antidepressant prescribing. Lower rates of prescribing in practices with south Asian trained doctors occur regardless of the ethnic composition of the practice population. Reasons for these differences are uncertain, but may include differences in explanatory models for presenting symptoms, and management strategies which rely less on a biomedical paradigm.