Excess mortality and post-stroke mortality in people with psychotic disorders in Hong Kong : a population-based study

Abstract

People with schizophrenia and other psychotic disorders exhibit markedly elevated risk of premature mortality and significantly shorter lifespan relative to the general population. Contemporary evidence shows that the mortality gap between psychotic patients and the general population is potentially widening over the past few decades despite health care advancement, with poor physical health being the likely culprit. In particular, psychotic disorders are associated with higher cardiometabolic morbidity and mortality, which possibly result from the combination of genetic predisposition, unhealthy lifestyle, adverse effects of antipsychotic medications, inequitable health care, and other unidentified factors. Existing findings on mortality in psychotic disorders were mostly derived from Western countries. In addition, the relationship between schizophrenia and short-term mortality risk following acute stroke is understudied and equivocal. This study aimed to outline the premature mortality in people with schizophrenia-spectrum disorders (SSD) and other non-affective psychoses (ONAP) in Hong Kong and substantiate the association between schizophrenia and post-stroke mortality. We identified all patients with the diseases of interest using a territory-wide electronic medical record database developed by the public and predominant health care provider in Hong Kong. The first part of the study investigated excess mortality in 46896 SSD and 20651 ONAP patients in 2006–2016, by estimating all-cause and cause-specific standardized mortality ratios (SMRs), and excess life-years lost (LYLs). Excess LYLs denotes the average reduction in life expectancy by taking into account the age-of-onset distribution of SSD and ONAP. Results showed that SSD and ONAP patients had higher all-cause (SMR: SSD 2.49 vs ONAP 2.00), natural-cause (1.80 vs 1.47), and unnatural-cause (6.97 vs 8.53) mortality rates than the general population. Respiratory diseases, cardiovascular diseases, and cancers accounted for the majority of deaths in patient cohorts. Men and women with SSD had 9.53 years and 8.07 years of excess LYLs, respectively. For ONAP, excess LYLs was 8.18 years for men and 5.44 years for women. The overall mortality gap remained largely unchanged for both patient groups over time despite improved longevity and declined unnatural-cause mortality rates. Our estimates are broadly consistent to previous population-based studies and concur with the potentially widening mortality gap observed in various countries, which highlights an urgent need for targeted interventions to improve the physical health of patients with psychotic disorders. The second part of the study investigated 30-day and 1-year mortality rates in 817 SSD patients compared with 8170 patients without psychotic disorder (10:1 matched to SSD patients on age, sex, treatment sites and calendar-year period for index admission) who were admitted for incident ischemic stroke in 2006–2016. Multivariate regression analyses adjusting for medical comorbidities revealed that SSD patients experienced elevated 1-year (16.9% vs 12.1%; p < 0.001) and 30-day (7.2% vs 5.3%; p = 0.053) mortality rates relative to control group. The effect of SSD on elevated mortality risk was even more pronounced, as indicated by higher odds, in men and nonelderly patients. Further research is warranted to identify factors contributing to excess post-stroke deaths among schizophrenia patients to facilitate development of effective interventions for mortality risk reduction.