Chronic kidney disease, proteinuria, and the risk of infective endocarditis in patients with diabetes: a nationwide retrospective cohort study.

AIMS The association between chronic kidney disease (CKD) and/or proteinuria and the risk of infective endocarditis (IE) in patients with CKD without replacement therapy remains unclear. This study evaluated the effect of CKD and/or proteinuria on the risk of IE among patients with diabetes. METHODS In this nationwide population-based cohort study, data on patients with diabetes who underwent a health checkup in 2009 were obtained from the Korean National Health Insurance Service database. Patients were categorised into three groups according to the estimated glomerular filtration rate (eGFR) and six groups according to dipstick proteinuria and were followed up until December 2018. The primary outcome was the development of IE, which was defined using ICD-10 codes (I33.x, I38.x, I39.8) combined with hospitalisation for >14 days or death within 14 days. The relative risk of IE was estimated using adjusted hazard ratios (aHRs). RESULTS In total, 866,918 patients were included, of whom 107,746 had an eGFR <60 mL/minute/1.73 m2. During the follow-up (median, 12.3 years), 821 cases of IE occurred. Patients with an eGFR <60 mL/minute/1.73 m2 had a higher risk of IE (aHR: 1.357, 95% confidence interval 1.098-1.676) than those with an eGFR ≥90 mL/minute/1.73 m2. The risk of IE increased as the severity of proteinuria increased, irrespective of the presence of CKD. CONCLUSION CKD and proteinuria in the population with diabetes are associated with an increased risk of developing IE. The association of proteinuria with the risk of IE may be more significant than that of impaired renal function. However, as this study relied on claim codes and single-time-point assessments of kidney parameters, potential misclassification and residual confounding-including lack of adjustment for healthcare-related exposures-should be considered.