Risk of empyema in patients with end-stage renal disease: a nationwide propensity-matched cohort study

Background: Empyema is a rare but important complication among patients with end-stage renal disease (ESRD). However, a nationwide, propensity-matched cohort study has never been performed. Methods: We conducted a retrospective cohort study using data from the National Health Insurance Research Database of Taiwan. The ESRD group consisted of 82 765 patients diagnosed between 2000 and 2008. The comparison group consisted of individuals without kidney disease selected at a 1:1 ratio matched by propensity score estimated with age, gender, year of diagnosis and comorbidities. The occurrence of empyema was monitored until the end of 2011. The hazard ratios (HRs) of empyema were estimated using the Cox proportional hazards model. Results: The incidence of empyema was 2.76-fold higher in the ESRD group than in the comparison group (23.7 vs. 8.19/10 000 person-years, P < 0.001), with an adjusted HR of 3.01 [95% confidence interval (CI) = 2.67-3.39]. There was no difference of the incidence of empyema between hemodialysis (HD) and peritoneal dialysis (PD) (adjusted HR = 0.96, 95% CI = 0.75-1.23). In addition, 30-day mortality rate since empyema diagnosis was significantly higher in ESRD group than the comparison group (15.9% vs. 10.9%), with an adjusted OR of 1.69 (95% CI = 1.17-2.44). Conclusion: The risk of empyema was significantly higher in patients with ESRD than in those without kidney disease. The occurrence of empyema was without difference in patients undergoing HD compared to those undergoing PD. The 30-day mortality rate since empyema diagnosis was also significantly higher in patients with ESRD.