Increased physical morbidity in patients with schizophrenia spectrum disorders (SSDs) is well documented. However, much less is known about the association between somatic comorbidities and psychosis treatment outcomes.

This cross-sectional study, nested within the larger frame of a prospective cohort study, was done in 2016 at Psychiatric Hospital Sveti Ivan, Zagreb, Croatia. Data were collected on a consecutive sample of 301 patients diagnosed with schizophrenia spectrum disorders who achieved a stable therapeutic dosage. Key outcome was the number of psychiatric rehospitalizations since diagnosis of the primary psychiatric illness. Predictors were number of physical and psychiatric comorbidities. By robust regression, we controlled different clinical, sociodemographic, and lifestyle confounding factors.

The number of chronic somatic comorbidities was statistically significantly associated with a larger number of psychiatric rehospitalizations, even after the adjustment for number of psychiatric comorbidities and large number of other clinical, sociodemographic, and lifestyle variables.

Chronic somatic comorbidities are associated with higher rates of psychiatric rehospitalization independently of psychiatric comorbidities and other clinical, sociodemographic, and lifestyle factors. Therefore, to treat psychosis effectively, it may be necessary to treat chronic somatic comorbidities promptly and adequately. Chronic somatic comorbidities should be considered equally important as the SSD, and should be brought to the forefront of psychiatric treatment and research with the SSD as one entity. The integrative approach should be the imperative in clinical practice.