The Occurrence of Warfarin-Related Nephropathy and Effects on Renal and Patient Outcomes in Korean Patients

BACKGROUND: Warfarin-related nephropathy (WRN) is a recently described disease entity, in which excessive warfarinization (international normalized ratio (INR) >3.0) causes acute kidney injury. Previous reports regarding WRN included few Asian patients who might have differed from the western WRN patients in terms of genetic and environmental factors. METHODS: During the period of March 2003 to December 2011, the data about a total of 1297 patients who had serum creatinine (sCr) level measured within 1 week after INR >3.0 and within 6 months before INR >3.0 was analyzed through the retrospective review of electronic medical records of a single tertiary hospital in Korea. RESULT: WRN developed in 19.3% of patients having excessive warfarinization. The incidence was higher in the chronic kidney disease (CKD) group than the non-CKD group. The risk of WRN increased as the basal serum albumin level decreased and was strongly associated with highest quartile serum AST level at post INR elevation and the presence of congestive heart failure. But the presence of atrial fibrillation was protective against the development of WRN. Neither the presence of CKD nor basal estimated glomerular filtration rate (eGFR) was an independent risk factor for WRN. Despite no difference in the basal sCr level, the sCr level was higher in patients with WRN than those without WRN after follow-up. The mortality rates were also higher in patients with WRN. CONCLUSIONS: WRN developed in 19.3% of patients having excessive warfarinization. A lower basal serum albumin, highest quartile serum AST level at post INR elevation, and congestive heart failure were associated with the occurrence of WRN. The development of WRN adversely affected renal and patient outcomes.