OBJECTIVE: To investigate the association between psychiatric comorbidity and in-hospital mortality in patients hospitalized for physical conditions in Germany. METHODS: This retrospective study used data from the hospital database of IQVIA (Frankfurt, Germany). Adults with a psychiatric disorder as a secondary diagnosis at hospital admission were matched (1:3) to those without a psychiatric disorder using a propensity score based on age, sex, hospital department, and primary diagnosis. Diagnoses of psychiatric and physical disorders relied on the ICD-10 classification. Associations between psychiatric comorbidity and in-hospital mortality were studied using logistic regression. RESULTS: There were 36,796 patients with (mean [SD] age 66.2 [14.7] years
53.4% men) and 110,388 patients without psychiatric comorbidity included in the study (mean [SD] age 66.1 [15.1] years
51.9% men). Overall, no statistical association was observed between psychiatric comorbidity and in-hospital mortality (OR = 1.00, 95% CI = 0.95-1.05). However, there was a positive and significant relationship in people aged ≤70 years and men, whereas a negative association was observed for those aged >
80 years and women. CONCLUSIONS: Psychiatric comorbidity was associated with increased in-hospital mortality in patients aged ≤70 years and men in hospitals in Germany. Further research is warranted to corroborate these findings in other countries.