Effect of regulatory warnings on antipsychotic prescription rates among elderly patients with dementia: a population-based time-series analysis.
BACKGROUND
Three warnings of serious adverse events associated with the use of atypical antipsychotic drugs among elderly patients with dementia were sent to health care professionals in Canada. We assessed the impact of these warnings on prescription rates of antipsychotic drugs in this patient population.


METHODS
We used prescription drug claims data from Ontario to calculate prescription rates of atypical and conventional antipsychotic drugs among elderly patients with dementia from May 1, 2000, to Feb. 28, 2007. We performed a time-series analysis to estimate the effect of each warning on rates of antipsychotic drug use.


RESULTS
Before the first warning, growth in the use of atypical antipsychotics was responsible for an increasing rate of overall antipsychotic use. Each warning was associated with a small relative decrease in the predicted growth in the use of atypical antipsychotic drugs: a 5.0% decrease after the first warning, 4.9% after the second and 3.2% after the third (each p < 0.05). The overall prescription rate of antipsychotic drugs among patients with dementia increased by 20%, from 1512 per 100 000 elderly patients in September 2002, the month before the first warning, to 1813 per 100 000 in February 2007, 20 months after the last warning.


CONCLUSIONS
Although the warnings slowed the growth in the use of atypical antipsychotic drugs among patients with dementia, they did not reduce the overall prescription rate of these potentially dangerous drugs. More effective interventions are necessary to improve postmarket drug safety in vulnerable populations.
Valiyeva
Elmira
E
The Department of Health Policy, Management and Evaluation, University of Toronto, Toronto, Ont. elmira.valiyeva@utoronto.ca
Herrmann
Nathan
N
Rochon
Paula A
PA
Gill
Sudeep S
SS
Anderson
Geoffrey M
GM
D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D000928:Antidepressive Agents / Q000008:administration & dosage* / Q000009:adverse effects; D001008:Anxiety Disorders / Q000188:drug therapy* / Q000453:epidemiology; D002983:Clinical Competence; D003863:Depression / Q000188:drug therapy* / Q000453:epidemiology; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D009864:Ontario / Q000453:epidemiology; D012189:Retrospective Studies
D000928:Antidepressive Agents