Best warfarin time in therapeutic range achieved using algorithm

In treating with warfarin, do physicians know best? New Zealand doctors second guessing an algorithm for anticoagulant dosing did not achieve superior results, according to a study published Sept. 2 in BMJ Open.

The study compared pharmacists and physicians both utilizing the same algorithm to assist in guiding warfarin dosing. Paul Harper, MD, of the Department of Clinical Haematology at Palmerston North Hospital, and colleagues, developed the algorithm as a component of a warfarin management system called INS Online.

The software package provided to physicians and pharmacists reviewed patient data, including results from regular tests, and adjusted anticoagulation accordingly. It also provided patients with updated calendars and reminded them when the next test would occur.

Harper et al followed more than 3,600 patients over a three-year period. One-third of patients were directly in a physician's care, while two-thirds were managed by pharmacists.

Researchers found that overall 72.9 percent of patients achieved successful moderation of anticoagulation with the algorithm. Pharmacists saw higher successes and were more likely to use the decision-making software than physicians, achieving 75.1 percent time in therapeutic range [TTR], against physicians 67.4 percent.

Physicians adjusted doses from the software recommendations in 28.2 percent of cases. Pharmacists second guessed the recommended dose in 21.1 percent of cases. Harper et al found that when physicians changed the dose from the software’s recommendations, more frequently than not, this resulted in underdosing the patient, who then spent more time outside of the therapeutic range.

These findings back up others in the field of software-based decision-making tools and also support greater reliance on such tools when dealing with cases that are not uniquely complicated. However, Harper et al found that pharmacists were more likely to report adverse events than physicians, suggesting that some adverse events may not have been recorded, but may have also been part of the decision-making process when ignoring the computer-recommended dose for a lower one.

“The doctors’ more cautious approach to management has potentially important clinical consequences,” they wrote. “There is a clear correlation between TTR and adverse outcomes in patients on warfarin, and patients with atrial fibrillation may be at particular risk as the incidence of stroke is higher when the INR [international normalized ratio] is below 2 (per prior studies).”

Still, Harper et al noted better outcomes were achieved when the algorithm recommendations were followed. To that end, they wrote, “The fact that the doctors achieved worse anticoagulant control and over-ride the algorithm more frequently for no clear clinical benefit implies that the doctor may achieve better control if they more closely followed the advice of the computer algorithm.”

Around the web

Eleven medical societies have signed on to a consensus statement aimed at standardizing imaging for suspected cardiovascular infections.

Kate Hanneman, MD, explains why many vendors and hospitals want to lower radiology's impact on the environment. "Taking steps to reduce the carbon footprint in healthcare isn’t just an opportunity," she said. "It’s also a responsibility."

Philips introduced a new CT system at ECR aimed at the rapidly growing cardiac CT market, incorporating numerous AI features to optimize workflow and image quality.

Trimed Popup
Trimed Popup