Atypical antipsychotics and hyperglycemic emergencies: Multicentre, retrospective cohort study of administrative data

OBJECTIVE To evaluate the relationship between initiation of atypical antipsychotic agents and the risk of hyperglycemic emergencies. METHOD We conducted a multicentre retrospective cohort study using administrative health data from 7 Canadian provinces and the UK Clinical Practice Research Datalink. Hospitalizations for hyperglycemic emergencies (hyperglycemia, diabetic ketoacidosis, hyperosmolar hyperglycemic state) were compared between new users of risperidone (reference), and new users of olanzapine, other atypical antipsychotics, and typical antipsychotics. We used propensity scores with inverse probability of treatment weighting and proportional hazard models to estimate the site-specific hazard ratios of hyperglycemic emergencies in the year following drug initiation separately for adults under and over age 66 years. Site-level results were pooled using meta-analytic methods. RESULTS Among 725,489 patients, 55% were aged 66+years; 5% of younger and 19% of older patients had pre-existing diabetes. Hyperglycemic emergencies were rare (1-2 per 1000 person years), but more frequent in patients with pre-existing diabetes (6-12 per 1000 person years). We did not find a significant difference in risk of hyperglycemic emergencies with initiation of olanzapine versus risperidone; however heterogeneity existed between sites. The risk of an event was significantly lower with other atypical (99% quetiapine) compared to risperidone use in older patients [adjusted hazard ratio, 95% confidence interval (CI): 0.69, 0.53-0.90]. CONCLUSIONS Risk for hyperglycemic emergencies is low after initiation of antipsychotics, but patients with pre-existing diabetes may be at greater risk. The risk appeared lower with the use of quetiapine in older patients, but the clinical significance of the findings requires further study.