To investigate the effect of medication adherence in patients with schizophrenia, we used data from an emergency inpatient registry to compare clinical features and treatment outcomes between a medication adherence group and a non-adherence group. In both groups, a hallucinatory-delusional state was the most frequent primary status at admission. The non-adherence group included more cases of compulsory hospitalization, and patients in this group tended to experience psychiatric crises with stronger symptoms and require hospitalization for longer periods. In contrast, patients in the adherence group exhibited milder symptoms with shorter hospitalization periods, and had a higher hospitalization frequency, longer disease duration, higher total number of hospitalization days, and shorter re-hospitalization durations. It is widely accepted that non-adherence increases the risk of re-hospitalization because of the recurrence of symptoms due to treatment interruption. However, in this study, the adherence group had a higher hospitalization frequency. A reason for this discrepancy may be that patients in the adherence group are more likely to seek treatment because they are more likely to notice psychological changes. Moreover, because this study included only hospitalized patients, it excluded patients who avoided hospitalization; their inclusion might have resulted in lower re-hospitalization rates in the adherence group. Thus, our study results do not contradict the accepted paradigm that non-adherence results in higher re-hospitalization rates. Our study results suggest that, because it affects the number of hospitalization episodes, the status of medication adherence at admission should be carefully considered during the selection of treatment plans for patients with schizophrenia.
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