SAN DIEGO – Patients with chronic kidney disease (CKD) and those on renin angiotensin system inhibitors and/or diuretics should have their renal function monitored during periods of overanticoagulation, results from a large retrospective study suggest.
“Unfortunately, warfarin-related nephropathy is quite hard to study,” Hugh Traquair, MD, the study’s lead author, said in an interview at the biennial summit of the Thrombosis & Hemostasis Societies of North America. “The best way to establish diagnosis is with a kidney biopsy. No one is very keen to stick a needle into a kidney when someone’s overanticoagulated. It’s been observed previously that acute kidney injury related to over-anticoagulation is more common in people with CKD, but we don’t know more about risk factors.”
Doug Brunk/MDedge News
Dr. Hugh Traquair
The primary outcome was AKI, defined as an acute increase in creatinine of greater than 26.5 micromol/L within 7-14 days of an INR 4 or greater. The secondary outcome was creatinine level within 3 months of the abnormal INR. The researchers excluded patients with AKI due to another cause, and those who lacked a creatinine level at baseline, within 7-14 days of an INR of 4 or greater, and/or at 3 months.
The median age of the 292 patients was 79 years, 55% were male, 30% were taking aspirin, and 77% were taking renin angiotensin inhibitors and/or diuretics. The control group consisted of 93 patients with a 12-month time in therapeutic range of 100%. The median age of controls was 68 years, 67% were male, and 9% had CKD. None of the controls had an AKI, said Dr. Traquair, a second-year internal medicine resident in the department of medicine at McMaster University.
Of the 292 patients with an INR of 4 or greater, 13% had an AKI, and the incidence of AKI was significantly higher in the CKD patients, compared with those who had a normal baseline creatinine level (19% vs. 10%; odds ratio, 2.1; P less than .05).
In a binomial logistic regression model, diuretic use was the only significant predictor of AKI (OR 3.4; P less than .05). The researchers also found that of the 52 patients with an INR of 4 or greater who did not use renin angiotensin system inhibitors and/or diuretics and did not have CKD, only 1 had an AKI (2%).