Movement Disorders in Elderly Users of Risperidone and First Generation Antipsychotic Agents: A Canadian Population-Based Study

BACKGROUND: Despite concerns over the potential for severe adverse events, antipsychotic medications remain the mainstay of treatment of behaviour disorders and psychosis in elderly patients. Second-generation antipsychotic agents (SGAs; e.g., risperidone, olanzapine, quetiapine) have generally shown a better safety profile compared to the first-generation agents (FGAs; e.g., haloperidol and phenothiazines), particularly in terms of a lower potential for involuntary movement disorders. Risperidone, the only SGA with an official indication for the management of inappropriate behaviour in dementia, has emerged as the antipsychotic most commonly prescribed to older patients. Most clinical trials evaluating the risk of movement disorders in elderly patients receiving antipsychotic therapy have been of limited sample size and/or of relatively short duration. A few observational studies have produced inconsistent results. METHODS: A population-based retrospective cohort study of all residents of the Canadian province of Manitoba aged 65 and over, who were dispensed antipsychotic medications for the first time during the time period from April 1, 2000 to March 31, 2007, was conducted using Manitoba's Department of Health's administrative databases. Cox proportional hazards models were used to determine the risk of extrapyramidal symptoms (EPS) in new users of risperidone compared to new users of FGAs. RESULTS: After controlling for potential confounders (demographics, comorbidity and medication use), risperidone use was associated with a lower risk of EPS compared to FGAs at 30, 60, 90 and 180 days (adjusted hazard ratios [HR] 0.38, 95% CI: 0.22–0.67; 0.45, 95% CI: 0.28–0.73; 0.50, 95% CI: 0.33–0.77; 0.65, 95% CI: 0.45–0.94, respectively). At 360 days, the strength of the association weakened with an adjusted HR of 0.75, 95% CI: 0.54–1.05. CONCLUSIONS: In a large population of elderly patients the use of risperidone was associated with a lower risk of EPS compared to FGAs.