OBJECTIVES: There is considerable interest in the psychiatric and neurological sequelae of COVID-19. Studies have indicated that COVID-19 patients have an increased risk of psychiatric and neurological sequelae. This study aimed to investigate the incidence of psychiatric and neurological sequelae of COVID-19 in Japan using claims data.

METHODS: This retrospective cohort study was conducted using LIFE Study data from March 1, 2020 to October 31, 2021. We created a primary cohort comprising patients with COVID-19. To comparatively analyze the incidences of psychiatric and neurological sequelae, we established a control cohort comprising patients with influenza in the same period. We used propensity score matching to control for baseline characteristics. To evaluate the influence of COVID-19 on psychiatric and neurological sequelae occurrence within 3 months and 6 months after a diagnosis of COVID-19, we conducted multivariate logistic regression analyses and Cox proportional hazards analyses.

RESULTS: The primary cohort of COVID-19 patients comprised 674 patients in the 3-month cohort and 460 patients in the 6-month cohort. Patients with COVID-19 were significantly more likely to develop a first psychotic disorder and insomnia within 3 months than the control cohort (psychotic disorder: odds ratio 1.46, 95% confidence interval [CI] 1.07-2.01; insomnia: 2.08, 1.62-2.68). In addition, COVID-19 was significantly associated with an increased incidence of psychiatric and neurological sequelae within 3 months when compared with the control cohort (psychotic disorder: hazard ratio 1.40, 95%CI 1.05-1.85, insomnia: 1.54, 1.31-1.81). The results for the 6-month follow-up period were the same as for the 3-month follow-up period (psychotic disorder: odds ratio 1.58, 95%CI 1.10-2.27; insomnia: 2.12, 1.57-2.86 and psychotic disorder: hazard ratio 1.47, 95%CI 1.07-2.02; insomnia: 1.54, 1.27-1.87).

CONCLUSIONS: COVID-19 was associated with an increased risk of some psychiatric sequalae in Japan. Although this study only indicated associations, it provides useful suggestions to guide further investigations of COVID-19.