Risk of pleural empyema in patients with schizophrenia: a nationwide propensity-matched cohort study in Taiwan

OBJECTIVE: Thoracic infection and pneumonia are prevalent in patients with schizophrenia; however, it is unclear whether patients with schizophrenia are at an increased risk of developing pleural empyema. DESIGN: A retrospective cohort study with propensity-matched cohorts with and without schizophrenia. SETTING: Using the National Health Insurance Research Database of Taiwan. PARTICIPANTS: We identified 55 888 patients with schizophrenia newly diagnosed in 2000–2011 and same number of individuals without schizophrenia as the comparison cohort, frequency matched by propensity scores estimated using age, sex, occupation, income, urbanisation, year of diagnosis and comorbidities. PRIMARY OUTCOME MEASURES: We assessed incident pleural empyema by the end of 2011 and used the Cox proportional hazards model to calculate the schizophrenia cohort to comparison cohort HR of pleural empyema. RESULTS: The overall incidence of pleural empyema was 2.44-fold greater in the schizophrenia cohort than in the comparison cohort (4.39vs1.80 per 10 000 person-years), with an adjusted HR of 2.87(95% CI 2.14 to 3.84). Stratified analyses by age, sex, occupation, income, urbanisation and comorbidity revealed significant hazards for pleural empyema associated with schizophrenia in all subgroups. CONCLUSIONS: Patients with schizophrenia are at an increased risk of developing pleural empyema and require greater attention and appropriate support.