Korean J Schizophr Res.  2023 Apr;26(1):24-31. 10.16946/kjsr.2023.26.1.24.

One-Year Clinical Outcomes After Diagnosis According to Early Medication Adherence in First-Episode Schizophrenia: A Nationwide, Health Insurance Data-Based Retrospective Cohort Study

• Choi W
• Joo SW
• Ahn S
• Choi YJ
• Kim SM
• Lee J

• KMID: 2542197
• DOI: http://doi.org/10.16946/kjsr.2023.26.1.24

Abstract

Objectives
Early pharmacologic intervention is considered necessary for improving the prognosis in patients with first-episode schizophrenia (FES). However, few nationwide population-based studies have focused on early medication adherence. We investigated the status of early adherence to antipsychotics and the effect of early adherence on later clinical outcomes in FES.
Methods
We used data from the South Korean Health Insurance Review Agency database (2009-2021). We selected 28,931 patients with FES who had a prescription record of at least one antipsychotic medication within 180 days after their diagnosis. We measured early medication adherence using the medication possession ratio (MPR) and compared demographic characteristics and results of psychiatric hospitalization between the adherence group (0.6≤MPR<1.1) and the non-adherence group (MPR<0.6).
Results
The average early medication adherence was 0.82 by MPR, and the non-adherence group accounted for 15.6% of all subjects. From 1 to 2 years after diagnosis, the adherence group showed a higher number of psychiatric hospitalizations per hospitalized patient but a shorter duration than the non-adherence group. Additionally, the proportion of patients who experienced psychiatric hospitalizations was smaller in the adherence group.
Conclusion
In patients with FES, early medication adherence is associated with lower rates of psychiatric hospitalization and shorter hospitalization durations.

Keyword

First-episode schizophrenia; Medication adherence; Medication possession ratio; Psychiatric hospitalization; 약물 소지 비율; 정신과적 입원; 초발 조현병; 투약 순응도

Figure

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  Fig. 1. Ways for calculating the medication possession ratio (MPR) value. A: MPR was calculated by dividing the number of days of antipsychotic medication prescribed outpatient within 180 days of first diagnosis by 180 days. B: If two or more antipsychotics were prescribed, the longest duration was selected. C: If hospitalized within 180 days of first diagnosis, the hospitalization period was excluded from the observation period.

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  Fig. 2. Distribution of the incident patients with first-episode schizophrenia who have taken antipsychotics for 6 months after diagnosis by medication possession ratio (MPR).

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