MORTALITY IN PATIENTS WITH SCHIZOPHRENIA ADMITTED FOR INCIDENT ISCHEMIC STROKE: A POPULATION-BASED COHORT STUDY

Abstract

Background: Evidence shows that schizophrenia is associated with increased incidence of cardiovascular diseases (CVD), including stroke. The relationship between schizophrenia and post-stroke mortality was understudied, and mixed findings were observed. Of note, none of these studies specifically explored the association of schizophrenia with short-term mortality after incident ischemic stroke. One of them specifically examined short-term mortality following ischemic stroke in schizophrenia patients, but it did not address potential confounding by patients who had past history of stroke. The only study which included solely incident stroke patients indicated that patients with psychotic disorders experienced higher short-term mortality ensuing incident stroke. Methods: We conducted a retrospective cohort study to investigate short-term mortality of schizophrenia patients after incident ischemic stroke. All individuals admitted for incident ischemic stroke between 2006 and 2016 in Hong Kong were identified using a territory-wide electronic health record database. 817 patients with an ICD-10 diagnosis of schizophrenia (F20) or schizoaffective disorder (F25) (termed schizophrenia henceforth) prior to index admission constituted the study group. The comparison group comprised 8170 patients (10:1 matched to schizophrenia patients on age, sex, treatment sites and calendar-period for index admission) without any non-affective psychoses, mania or bipolar disorder (F20, F22-25, F28-31). Results: Multivariate logistic regression revealed that schizophrenia patients had higher 1-year (OR [95% CI] = 1.51 [1.22 – 1.85]) and marginally higher 30-day (OR [95% CI] = 1.34 [1.00 – 1.79]) mortality following incident ischemic stroke, after adjusting for medical comorbidities, including hypertension, diabetes, hyperlipidemia, alcohol and substance use disorders and other comorbidities quantified by Charlson-Deyo comorbidity index. Additional age- (<65 years and ≥65 years) and gender-stratified analyses revealed similar results. Elevated 1-year mortality was exhibited by all schizophrenia subgroups, being more pronounced in younger patients (OR [95% CI] = 2.02 [1.38 – 2.96]). Increase in 30-day mortality was only seen in younger (OR [95% CI] = 1.75 [1.04 – 2.95]) and male (OR [95% CI] = 1.63 [1.06 – 2.50]) schizophrenia patients. Discussion: Our results of heightened short-term post-stroke mortality in schizophrenia were in line with the only previous study which compared short-term mortality ensuing incident stroke in patients with and without psychotic disorders. This intuitive result may be explained by some studies which demonstrated that schizophrenic stroke patients were less likely to receive reperfusion treatments and prophylactic medications. The absence of data on lifestyle factors, antipsychotic treatment and post-stroke management is a major limitation in our study. In conclusion, our results indicated that schizophrenia is associated with increased short-term mortality after incident ischemic stroke. Further research is warranted to clarify the contribution of possible risk factors to post-stroke mortality in schizophrenia patients.