Physical and Psychiatric Comorbidities and Their Influence on All-Cause and Suicide Mortality: A Longitudinal Study of 109,900 Young Patients with Schizophrenia

Background: Schizophrenia frequently coexists with various physical and psychiatric comorbidities, but the influence of these comorbidities on mortality outcomes, particularly suicide mortality, among young patients with schizophrenia remains inadequately understood. Methods:We followed 109,900 young patients with schizophrenia aged 10-44 years for up to ten years.We assessed 12 physical diseases, including diabetes, myocardial infarction, chronic liver disease, and malignancies, and two psychiatric disorders, namely, alcohol use disorder and substance use disorder (SUD).Time-dependent Cox regression models were used to analyze the associations of these comorbidities with all-cause and suicide mortality.Results: SUD was strongly associated with increased all-cause mortality (hazard ratio [HR]: 1.80) and suicide mortality (HR: 3.76).Malignancies (HR: 14.39) and chronic kidney disease (HR: 6.46) were also strongly linked to all-cause mortality.The risk of all-cause mortality increased with the numbers of comorbidities (HR: 2: 2.02 vs. 1: 1.45).No significant association was found between physical comorbidities and suicide risk.Conclusions: SUD is a significant risk factor for suicide mortality among young patients with schizophrenia.Physical comorbidities such as malignancies and chronic kidney disease are primarily associated with increased all-cause mortality in this population.