Comparative risk of parkinsonism associated with olanzapine, risperidone and quetiapine in older adults

Te-yuan Chyou, Prasad Nishtala

Research output: Contribution to conferenceAbstractpeer-review


Background: In New Zealand (NZ), clinical trials provide limited information on the comparative risk of Parkinsonism associated with secondgeneration antipsychotics (SGAs) in older adults.
Objectives: This study examines the incidence of Parkinsonism in new users of SGAs in older adults (≥ 65 years). As secondary analyses, we
examined the risk of Parkinsonism by type and dose of SGA and also the age-sex interactions.
Methods: We used the NZ national minimum data set and the pharmaceutical collections to identify older adults who had a diagnosis of
Parkinsonism and who started taking olanzapine, risperidone or quetiapine between 01/01/2005 and 31/12/2016. Confounding was mitigated
using propensity score methods. The Cox proportional hazard (COXPH) regression model with inverse treatment probability weighting (ITPW) was
used to evaluate the risk of Parkinsonism associated with SGAs, using quetiapine as the reference. We used the generalized propensity score
method, where daily doses as continuous variables were used as exposure variables, to evaluate the dose-response risk of Parkinsonism
associated with SGAs.
Results: After ITPW adjustment for confounders including comorbidity, the COXPH model showed that compared to quetiapine, the use of
olanzapine and risperidone were associated with an increased risk of parkinsonism (ITPW-adjusted hazard ratio (ITPW-HR) 1.76, 95% confidence
interval 1.57 to 1.97; and ITPW-HR 1.31 (1.16 to 1.49) respectively). The dose-response risk of Parkinsonism was highest for olanzapine (HR 1.69
(1.40 to 2.05)) and the least for quetiapine (HR 1.22 (1.14 to 1.31)). Age-sex interactions revealed risk of Parkinsonism in the 65-74yr group was
higher for both sexes with risperidone compared to olanzapine, but the risk increased significantly with olanzapine for both sexes in the 85yr+
Conclusions: The study found that quetiapine use might be associated with a relatively lower risk of Parkinsonism than olanzapine or risperidone
in older adults. Prescribers should exercise caution when using olanzapine in the oldest old
Original languageEnglish
Publication statusPublished - 1 Oct 2021
Event36th ICPE conference Berlin, Aug 26-30 - Virtual, Berlin, Germany
Duration: 26 Aug 202030 Sept 2021


Conference36th ICPE conference Berlin, Aug 26-30
Internet address


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