Increased somatic morbidities in schizophrenic patients and their association with HRQoL are well documented. Less is known about their association with schizophrenia treatment outcome.

To explore whether the number of somatic comorbidities is associated with poorer psychosis treatment outcome independently of psychiatric comorbidities and other clinical and socio-demographic parameters.

To improve understanding of association of somatic morbidities on treatment outcome of schizophrenic patients.

This nested-cross-sectional study was done during 2016 at Psychiatric hospital Sveti Ivan, Zagreb-Croatia on the sample of 301 patients diagnosed with schizophrenia spectrum disorder. Outcomes were the number of psychiatric rehospitalizations since primary psychiatric diagnosis and the composite of significant improvement measured by CGI-S and the best self-rated health defined as 4th quartile of EQ-5D-5L VAS. Predictors were number of somatic and psychiatric comorbidities. By logistic regression, we controlled socio-demographic and clinical confounders.

Having two or more somatic comorbidities was significantly associated with the failure to achieve the composite of improvement. The number of somatic comorbidities was significantly associated with increase in psychiatric hospitalizations, even after the adjustment for psychiatric comorbidities and large number of clinical and socio-demographic variables.

Chronic somatic comorbidities are associated with poorer psychosis treatment outcome independently of psychiatric comorbidities and other factors. Therefore, to treat psychosis effectively it may be essential to treat chronic somatic comorbidities promptly and adequately. The integrative approach should be the imperative in clinical practice.