Variations in anxiolytic and hypnotic prescribing by GPs: a cross-sectional analysis using data from the UK Quality and Outcomes Framework

Abstract

Background: Wide variations in anxiolytic and hypnotic prescribing by GPs in England have been described, but are largely unexplained.

Aim: To examine the relationships between the volume of anxiolytics and hypnotics prescribed by GPs and their practice characteristics, population demography, and performance indicators.

Design of study: Cross-sectional study.

Setting: All general practices in England.

Methods: A dataset was constructed for 8469 (98.8%) general practices including: standardised prescribing volume data for anxiolytics and hypnotics (average daily quantities per 1000 STAR-PUs [Specific Therapeutic group Age-sex weightings Related Prescribing Units]), practice descriptors, Index of Multiple Deprivation 2004, ethnicity data (2001 UK Census), and Quality and Outcomes Framework (QOF) data.

Results: The standardised volume of anxiolytics and hypnotics prescribed varied eightfold between practices on the 5th and 95th centiles. A regression model was constructed which explained 20.5% of the variation. Higher prescribing practices were located in more deprived areas (standardised beta 0.31), but also in areas with a lower proportion of ethnic minorities (black or black British = -0.22; Asian or Asian British = -0.12). Higher volumes were also prescribed by practices with lower QOF scores ('Clinical Care' domain = -0.12; 'Organisational' domain = -0.08). Other significant but weaker predictors were: lower proportions of female GPs, higher recorded prevalence of serious mental illness and non-training status. The proportion of GPs trained outside UK was not a predictor.

Conclusion: Demographic factors were more powerful determinants of prescribing than characteristics of the practice itself. Nevertheless, the findings provide some support for the notion that high prescribing practices were less well developed, in that their QOF scores were lower and they were less likely to be training practices.

Figure 1

Total number of average daily quantities (in 1000s) according to all anxiolytic and hypnotic prescriptions dispensed in the community in England from 1998 to 2005. Barbiturates are excluded. Source: Department of Health, Statistics Division 1E, Prescription Cost Analysis System).

Figure 2

Frequency histograms for the volume of anxiolytics and hypnotics prescribed (in average daily quantities per 1000 STAR-PUs [Specific Therapeutic group Age-sex weightings Related Prescribing Units]) in 8469 general practices in England.