Patterns of Co-Medications Among People With Schizophrenia in Hong Kong

OBJECTIVES: Co-medications are a common concern among individuals with schizophrenia, yet no systematic investigation has been conducted among this population in Hong Kong. The aim of this study is to investigate the patterns of co-medication use and prevalence of polypharmacy among people with schizophrenia in Hong Kong.

METHODS: The electronic medical record database of the Hong Kong Clinical Data Analysis and Reporting System (CDARS) to was used to identify patients diagnosed with schizophrenia between January 1, 1993 and December 31, 2019. The cumulative duration of medication use within the cohort was calculated as the sum of the prescription periods for each patient. Co-medication was defined as the simultaneous use of at least two medications on the same day, and polypharmacy was defined as the simultaneous use of at least five medications on the same day.

RESULTS: A total of 70,396 patients diagnosed with schizophrenia were identified. They were prescribed a single medication during 13.32% of the observation period, and two medications concurrently during 23.10% of the observation period. Polypharmacy was prevalent, accounting for 15.89% of the observation period. Regarding specific medication use, antipsychotics were used during 76.53% of the observation period, and were frequently combined with other medications (64.64% of the observation period), including antiparkinson drugs (43.31%), antidepressants (13.91%), antiepileptic drugs (13.62%), beta-adrenoceptor blocking drugs (12.89%), and anxiolytics (11.80%). Among the class of antipsychotics, antipsychotic monotherapy and the concurrent use of two antipsychotics accounted for 54.11% and 19.95% of the observation period, respectively, while the use of three or more antipsychotics was less common (2.48%).

CONCLUSIONS: Polypharmacy remained a common practice among people with schizophrenia. The concurrent use of other medications during antipsychotic treatment was primarily related to managing the side effects of antipsychotics and addressing psychiatric comorbidities among individuals with schizophrenia.