Antipsychotic Treatment Duration in Children and Adolescents: A Register-Based Nationwide Study.

Objective: Despite the increasing use of antipsychotic drugs in children and adolescents in many countries, little is known about the treatment duration in this vulnerable population. The present nationwide study investigated the duration of antipsychotic treatment and factors associated with treatment discontinuation in Finnish children and adolescents. Methods: All subjects aged 1-17 years who had started a second-generation antipsychotic (SGA) drug (risperidone, quetiapine, aripiprazole, or olanzapine) between January 2008 and December 2016 ( n  = 20,932) were extracted from the Finnish Prescription Registry and followed up until December 31, 2017. Treatment duration was calculated as the time between the initial purchase of medication and treatment discontinuation. Treatment was considered discontinued if the treatment-free gap was more than 270 days. The associations between explanatory factors and treatment discontinuation were analyzed with the Cox proportional hazards models. Results: The mean and median treatment durations were 509 days (95% confidence interval [95% CI]: 500-517 days) and 317 days (95% CI: 306-325 days), respectively. The duration was shorter in girls than in boys ( p  < 0.001). Of all SGA users, 35.1% used antipsychotics less than 50 days and 16.0% used more than 600 days. Shorter treatment duration was associated with age groups of 7-12 and 13-15 years compared with 1-6 years (hazard ratio [HR]:1.23 [95% CI: 1.11-1.36]; HR: 1.35 [95% CI: 1.21-1.51], respectively) and initiating treatment with quetiapine or olanzapine compared with risperidone (HR: 1.18 [95% CI: 1.12-1.25]; HR: 1.66 [95% CI 1.46-1.88], respectively). Switching of SGA drug during treatment was associated with longer treatment duration (HR: 0.40 [95% CI: 0.38-0.43]). Conclusions: In children and adolescents, the mean treatment duration of SGAs was relatively long given that the majority of SGA use was off-label. Older age and initiating treatment with quetiapine were associated with earlier treatment discontinuation, whereas switching of antipsychotic drug during therapy increased the possibility of longer SGA use.