Trends in utilization and dosing of antipsychotic drugs in Scandinavia: Comparison of 2006 and 2016

Aims The aim of this study was to investigate time trends in dosing and prevalence of antipsychotic prescriptions in Scandinavia. Methods We retrieved data on antipsychotic use between 2006 and 2016 from Danish, Norwegian and Swedish national prescription registers. For each antipsychotic, we calculated prevalence of use and mean doses, overall and for specific age groups (young, adults and elderly). Results Antipsychotic use in Scandinavia increased from 16.5 to 17.2 users/1000 inhabitants between 2006 and 2016 (+2.4%, annual change: 0.07 users/1000 inhabitants/year, 95% CI: 0.02-0.20, P = 0.02). In 2006, chlorprothixene and levomepromazine were the most commonly used antipsychotics. By 2016, quetiapine was the most used antipsychotic in all three countries and across all age groups, with an overall 1-year prevalence of 4.05-9.97 users/1000 inhabitants (annual change: 0.57 users/1000 inhabitants/year, 95% CI: 0.54-0.60, P < 0.001). Quetiapine showed a marked decrease in mean doses during the 11-year study period (0.46-0.28 defined daily doses (DDD)/user/day: 39.1%, -0.02 DDD/user/day/year, 95% CI: -0.020 to -0.015, P < 0.001). In 2016, the highest mean doses were seen for clozapine (0.90-1.07 DDD/user/day) and olanzapine (0.66-0.88 DDD/user/day). Conclusions There is an increased prevalence of antipsychotic prescriptions that coincides with low and/or decreasing mean doses of the majority of commonly used antipsychotics in Scandinavia. Of all antipsychotics, this development was most pronounced for quetiapine. Reasons for and consequences of increased antipsychotic use that lasts shorter periods of time requires further study.