• atypical antipsychotic;
  • parkinsonism;
  • fracture;
  • pharmacoepidemiology


Our objective was to estimate the effect of atypical antipsychotics (AAs) on the rate of fractures in a parkinsonism population. We conducted an age- and state-matched nested case-control study in five states (CA, FL, NY, OH, IL) using the Medicaid analytic extract from 2001 to 2002. Eligible participants had a diagnosis of parkinsonism, excluding persons with secondary parkinsonism, bone cancer, bone infections, schizophrenia, schizoaffective disorder, and those who used conventional antipsychotics. The primary outcome was the occurrence of a fracture of the femur, ankle, fibula, tibia, humerus, radius, or ulna (N = 851). Risk-set sampling defined controls (N = 4220). We used conditional-logistic regression to derive adjusted odds ratios (AOR) and 95% confidence intervals of the association between fracture and use of quetiapine, risperidone, or olanzapine in the 60 days before the index date compared to nonuse. After adjustment for confounding, use of quetiapine (AOR 2.4; 95% CI 1.5–3.8), risperidone (AOR 1.2; 95% CI 0.9–1.7), or olanzapine (AOR 1.7; 95% CI 1.2–2.4) was associated with a higher rate of fracture. Use of an AA was associated with a higher rate of fracture in persons with parkinsonism. Prescribers must be cautious when using these agents in elderly persons with parkinsonism. © 2009 Movement Disorder Society