Acute and delayed psychiatric sequelae among patients hospitalised with COVID-19: a cohort study using LIFE study data.

Background: Characterising the psychiatric sequelae of coronavirus disease 2019 (COVID-19) can inform the development of long-term treatment strategies. However, few studies have examined these sequelae at different time points after COVID-19 infection. Aims: The study aimed to investigate the incidences and risks of acute and delayed psychiatric sequelae in patients hospitalised with COVID-19 in Japan. Methods: This retrospective cohort study was conducted using a database comprising healthcare claims data from public health insurance enrollees residing in a Japanese city. We analysed a primary cohort comprising patients hospitalised with COVID-19 between March 2020 and July 2021 and two control cohorts comprising patients hospitalised with influenza or other respiratory tract infections (RTI) during the same period. We calculated the incidences of acute (1-3 months after infection) and delayed (4-6 months after infection) psychiatric sequelae. These sequelae were identified using diagnosis codes and categorised as mood/anxiety/psychotic disorder, mood disorder, anxiety disorder, psychotic disorder or insomnia. Multivariable logistic regression models were used to estimate the odds ratios (ORs) of psychiatric sequelae occurrence after COVID-19 infection compared with influenza and other RTI. Results: The study population with acute psychiatric sequela consisted of 662 patients with COVID-19, 644 patients with influenza, and 7369 patients with RTI who could be followed for 3 months; the study population with delayed psychiatric sequelae consisted of 371 patients with COVID-19, 546 patients with influenza, and 5397 patients with RTI who could be followed for 6 months. In the analysis of acute psychiatric sequelae, COVID-19 had significantly higher odds of mood/anxiety/psychotic disorder (OR: 1.39, p=0.026), psychotic disorder (OR: 2.13, p<0.001), and insomnia (OR: 2.59, p<0.001) than influenza, and significantly higher odds of insomnia (OR: 1.44, p=0.002) and significantly lower odds of anxiety disorder (OR: 0.56, p<0.001) than other RTI. In the analysis of delayed psychiatric sequelae, COVID-19 had significantly higher odds of psychotic disorder (OR: 2.25, p=0.007) than influenza, but significantly lower odds of anxiety disorder (OR: 0.55, p=0.011) than other RTI. Conclusions: COVID-19 was generally associated with an increased risk of psychiatric sequelae occurring within 3 months after infection, but had a lower risk of new psychiatric sequelae developing 4-6 months after infection.