SAN DIEGO – A simple intervention of initial warfarin dose capping in hospitalized patients aged 85 years and older led to significant reductions in supratherapeutic INRs without a significant change in length of stay, a single-center study showed.
“We’re excited to see if these results are reproducible,” Jonathan Falsetta, PharmD, said at the biennial summit of the Thrombosis & Hemostasis Societies of North America. “We do feel that it may represent an important step forward in warfarin safety in a vulnerable patient population.”
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Dr. Jonathan Falsetta
In a previous pilot study, Dr. Falsetta and his associates retrospectively reviewed supratherapeutic INRs in 21 patients at Northwell Health’s Plainview Hospital, a 204-bed teaching hospital in Long Island, N.Y., between January and September of 2015. These were defined as an INR of 5 or greater, not present on admission. Of the 21 patients, 12 were younger than 85 years old. Their initial dose of warfarin was 4 mg, and the peak INR ranged from 5.15 to 9.29. The remaining nine patients were at least 85 years-old. Their average initial dose was 5 mg, and their peak INR range was 5.17 to 12.2.
“From this we gathered that we had an issue with dosing,” said Dr. Falsetta, who is assistant director of pharmacy clinical educational services at Plainview Hospital. “These patients were spiking dangerously high INRs, and we needed to do something about it.”
A review of current medical literature revealed a lack of well-validated recommendations regarding warfarin initiation in older patients, so Dr. Falsetta and his associates set out to create their own dose-capping recommendation. This involved limiting the initial dose of warfarin to 2.5 mg or less for hospitalized patients aged 85 years and older.
“We wanted this to be applicable to patients regardless if they were warfarin naïve or if they had been on warfarin prior to admission,” he said.
Before the roll out, clinical pharmacists and pharmacy residents conducted provider education on the initial dose capping protocol. Providers could order initial doses that exceeded 2.5 mg with valid clinical reasoning. Outcomes of interest were dosing protocol compliance and post-intervention analysis of INRs in this patient population. The pre-intervention period spanned from Nov. 1, 2014 through Oct. 31, 2015, while the post-intervention period spanned from Nov. 1, 2015 through Oct. 31, 2017. Dr. Falsetta reported data from 768 patients.
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