Psychological Medicine

Original Articles

The DEBIT trial: an intervention to reduce antipsychotic polypharmacy prescribing in adult psychiatry wards – a cluster randomized controlled trial

A. Thompsona1, S. A. Sullivana1 c1, M. Barleya1, S. O. Strangea1, L. Moorea2, P. Rogersa3, A. Siposa1 and G. Harrisona1

a1 Academic Unit of Psychiatry, University of Bristol, Bristol, UK

a2 Cardiff Institute of Society, Health and Ethics, Cardiff University, Cardiff, UK

a3 School of Care Sciences, University of Glamorgan, Pontypridd, UK


Background Clinical guidelines advise against prescribing more than one antipsychotic with limited exceptions. Despite this, surveys continue to report high antipsychotic polypharmacy rates. The aim of the study was to investigate the effectiveness of a multi-faceted intervention in reducing prescribing of antipsychotic polypharmacy on general adult psychiatry wards, compared with guidelines alone.

Method A pragmatic cluster randomized controlled trial recruited 19 adult psychiatric units (clusters) from the South West of England. Participants were all ward doctors and nurses. The multi-faceted intervention comprised: an educational/CBT workbook; an educational visit to consultants; and a reminder system on medication charts.

Results The odds of being prescribed antipsychotic polypharmacy in those patients prescribed antipsychotic medication was significantly lower in the intervention than control group when adjusted for confounders (OR 0.43, 95% CI 0.21–0.90, p=0.028). There was considerable between-unit variation in polypharmacy rates and in the change in rates between baseline and follow-up (5 months after baseline).

Conclusion The intervention reduced levels of polypharmacy prescribing compared to guidelines alone although the effect size was relatively modest. Further work is needed to elicit the factors that were active in changing prescribing behaviour.

(Received January 11 2007)

(Revised June 14 2007)

(Accepted July 02 2007)

(Online publication September 10 2007)


c1 Address for correspondence: Ms S. Sullivan, Academic Unit of Psychiatry, University of Bristol, Bristol BS6 6JL, UK. (Email: