Influencing Factors of Multiple Adverse Outcomes Among Schizophrenia Patients Using Count Regression Models: A Cross-Sectional Study

Abstract Background: Schizophrenia patients have increased risks of several adverse outcomes, including violent crime, aggressiveness and suicide. However, studies of different adverse outcomes in the same population are rare and the influencing factors for these outcomes need clarification by appropriate models. This study aimed to identify influencing factors of these adverse outcomes by examining and comparing different count regression models.Methods: This study included schizophrenia patients who had at least once follow-up record in the Guangdong Mental Health Center Network Medical System during 2020. Three types of adverse outcomes including a) aggressiveness with police dispatch or violence crime, b) aggressiveness without police dispatch, and c) self-harm or suicide attempts. First, we investigated the incidence of these adverse outcomes in each type. Second, the Poisson, negative binomial (NB), zero-inflated Poisson (ZIP), and zero-inflated negative binomial (ZINB) regression models were fitted and compared for their intensity. Finally, We analysed associations between these adverse outcomes intensity and sociodemographic, clinical factors with the best model. Results: A total of 130474 schizophrenia patients were selected. Each type of adverse outcomes was reported by less than 1% of schizophrenia patients in 2020. NB regression model is the best model for fitting the number of aggressiveness without police dispatch because of the best goodness of fit and relatively simple interpretation, whereas ZINB models for the other two outcomes. Age, sex, and history of adverse outcomes were influencing factors shared across these adverse outcomes. Higher educational level, employment were protective factors shared between aggressiveness with police dispatch or violent crime , and aggressiveness without police dispatch. Aggressiveness without police dispatch , and self-harm or suicide attempts shared older onset age (≥18 years) as a risk factor. Family history of mental disease was a risk factor of self-harm or suicide attempts individually.Conclusions: NB and ZINB models were selected for fitting the number of adverse outcomes in our studies. Influencing factors for adverse outcomes intensity included both those shared across different types and those individual to specific types. Therefore, combined and customized tools in risk assessment and intervention for different types of these outcomes might be necessary.