Free-of-charge dispensing of antipsychotics for schizophrenia in Denmark: Impact on the nationwide prescription registry and redemption of somatic medications

Abstract

Objective: Free-of-charge dispensing of antipsychotics for schizophrenia was introduced in Denmark around 2008. However, free-of-charge dispensing is not recorded in the Danish National Prescription Register (DNPR), potentially introducing bias and misclassification. Methods: We identified all 30 275 individuals with a first-episode schizophrenia diagnosis in Denmark between 1 January 1999 and 1 March 2017 including all redeemed prescriptions registered in the DNPR during the 2 years after the schizophrenia diagnosis. For each calendar year, we calculated the proportion of individuals who had filled ≥1 prescription for psychotropic and/or somatic medications within the first 2 years after the schizophrenia diagnosis. Results: From 2007 to 2017, the proportion of individuals with prescription-records for any psychotropic medication during the 2 years after the schizophrenia diagnosis decreased from 88% to 74%, particularly antipsychotics (from 83% to 61%) and antidepressants (from 49% to 35%). This was particularly observed among those aged 18–30 years at the schizophrenia diagnosis. A similar decrease was not observed for prescription-records of somatic medications. Conclusion: The introduction of free-of-charge antipsychotics has affected the redemption of specific psychotropic drugs in the DNPR in first-episode schizophrenia. This limitation needs to be considered in register-based studies and emphasizes the need to identify solutions.