Identifying psychiatric morbidity and comorbidity patterns associated with COVID-19 mortality. A register-based cohort study from Catalonia

Background There is limited evidence on the association between psychiatric morbidity and COVID-19 mortality. Methods We used deidentified electronic health records from the Catalan public health system to evaluate the association between number of mental disorders and COVID-19 mortality. Adults diagnosed with a mental disorder in Catalonia’s mental health services (from to 2017–2019) were compared to a matched (1:1) control group by sex, age, and area of residence. COVID-19 mortality risk was evaluated from February to December 2020. Odds ratios (OR) with 95% confidence intervals (CI) were estimated for the association between the number of mental disorders and COVID-19 mortality. To examine if different patterns of psychiatric comorbidity were related to COVID-19 death, we performed K-means cluster analysis on individuals with ≥2 disorders, stratified by COVID-19 death. Results The final sample included 785,378 adults (392,689 with ≥1 mental disorder). Mortality risk increased with the number of mental disorders: OR 1.23 (95% CI: 1.11–1.35) for one mental disorder, up to 5.21 (95% CI: 1.34–20.27) for four or more. Cluster analysis (n=84,207) identified seven psychiatric comorbidity profiles among those who did not die of COVID-19, and six profiles among those who died, with substantial comparability between cohorts. Conclusion An increasing number of psychiatric diagnoses was associated with greater COVID-19 mortality, while specific comorbidity patterns showed limited differential influence. This suggests that it is not the specific combination of mental disorders that influences COVID-19 death outcomes, but rather the overall burden of multiple diagnoses.