BROOKLYN, NY—A retrospective cohort study recently evaluated warfarin prescription, quality of international normalized ratio (INR) monitoring and of INR control in patients with atrial fibrillation (AF) and chronic kidney disease (CKD) at the VA

The study, published recently in the journal Heart, looked at 123,188 veterans newly diagnosed AF at the VA.1

Researchers from the Maimonides Medical Center and colleagues, including representatives from the VA Palo Alto, CA, Healthcare System, evaluated anticoagulation prescription, INR monitoring intensity and time in and outside INR therapeutic range (TTR) stratified by CKD.

Results indicate that warfarin use decreased with increasing severity of CKD—57.2%-46.4%—but was higher among patients on dialysis, 62.3%.

While INR monitoring intensity was similar across CKD strata, the proportion with TTR at or above 60% decreased with CKD severity, with only 21% of patients on dialysis achieving that level.

After multivariate adjustment, the magnitude of TTR reduction increased with CKD severity, according to the study. Patients on dialysis had the highest time, 30%, markedly out of range with INR less than1.5 or above 3.5%. At the same time, 12% of INR time was greater than 3.5, and low TTR persisted for up to three years.

“There is a wide variation in anticoagulation prescription based on CKD severity,” study authors conclude. “Patients with moderate-to-severe CKD, including dialysis, have substantially reduced TTR, despite comparable INR monitoring intensity. These findings have implications for more intensive warfarin management strategies in CKD or alternative therapies such as direct oral anticoagulants.”

1: Yang F, Hellyer JA, Than C, Ullal AJ, Kaiser DW, Heidenreich PA, Hoang DD, Winkelmayer WC, Schmitt S, Frayne SM, Phibbs CS, Turakhia MP. Warfarin utilisation and anticoagulation control in patients with atrial fibrillation and chronic kidney disease. Heart. 2016 Nov 15. pii: heartjnl-2016-309266. doi: 10.1136/heartjnl-2016-309266. [Epub ahead of print] PubMed PMID: 27852694.