Schizophrenia and the incidence of cardiovascular morbidity: a population-based longitudinal study in Ontario, Canada

Despite the high rates of cardiovascular mortality among people with schizophrenia, little is known about the incidence of cardiovascular morbidity in this population. We assessed whether individuals diagnosed with schizophrenia, in comparison to a population-proxy comparison group (comprised of individuals receiving an appendicitis-related primary diagnosis), would have a significantly greater risk of subsequent readmission to an inpatient or Emergency Department setting with a cardiovascular condition.

Using inpatient hospital discharge records from April 1, 2002 to March 31, 2006 in Ontario, Canada, we constructed a population-based cohort study of patients who were followed for a period up to 4 years. Individuals with a primary ICD-10 (F20) schizophrenia diagnosis (n=9815) were matched with persons with a primary ICD-10 appendicitis-related diagnosis (K35-37) on sex, age, average neighbourhood income level, and amount of follow-up time available. We used a Cox regression procedure to estimate group differences in time-to-readmission with a cardiovascular-related diagnosis.

Individuals in the Schizophrenia group had a significantly greater adjusted risk of readmission for a cardiovascular event in comparison to individuals in the Appendicitis group [adjusted hazard ratio (AHR)=1.43, 95% CI, 1.22-1.69].

Given the elevated risk of cardiovascular morbidity among individuals with schizophrenia, our findings add to the importance of screening and intervention programs for metabolic disorders and known cardiovascular risk factors among patients with schizophrenia.