Comparative risk of Parkinsonism associated with olanzapine, risperidone and quetiapine in older adults-a propensity score matched cohort study

Te-yuan Chyou, Revathi Nishtala, Prasad Nishtala

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Purpose: The purpose of this study was to examine the incidence of Parkinsonism in
new users of second-generation antipsychotics (SGAs) in older adults (≥65 years). In the secondary analyses, we examined the risk of Parkinsonism by type and dose of SGA and conducted age-sex interactions.
Method: This population-based study included older adults who had a new-onset
diagnosis of Parkinsonism and who started taking olanzapine, risperidone or
quetiapine between 1 January 2005, and 30 December 2016. The Cox proportional
hazard (COXPH) model with inverse treatment probability weighted (ITPW)
covariates was used to evaluate the risk of new-onset Parkinsonism associated with
SGAs, using quetiapine as the reference. We used the Generalized Propensity Score
method to evaluate the dose-response risk of Parkinsonism associated with SGAs.
Results: After ITPW adjustment for covariates, the COXPH model showed that compared to quetiapine, the use of olanzapine and risperidone were associated with an increased risk of Parkinsonism. The ITPW-hazard ratios are 1.76 (95% confidence interval 1.57-1.97) and 1.31 (95%CI 1.16-1.49), respectively. The dose-response risk of Parkinsonism was highest for olanzapine with a hazard ratio of 1.69 (95%CI 1.40-2.05) and the least for quetiapine with a hazard ratio of 1.22 (95%CI 1.14-1.31). The risk of Parkinsonism in the 65 to 74-year age group was higher for both sexes with risperidone compared to olanzapine, but the risk increased with olanzapine for both sexes in the 85+ age group.
Conclusion: The study found that the risk of new-onset Parkinsonism in older adults is 31% and 76% higher with risperidone and olanzapine respectively compared to
adverse effects, atypical antipsychotics, elderly, extrapyramidal side effects,
Original languageEnglish
Article numberpds.5007
JournalPharmacoepidemiology and Drug Safety
Early online date16 Apr 2020
Publication statusE-pub ahead of print - 16 Apr 2020

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