SAN DIEGO (FRONTLINE MEDICAL NEWS) – The incidence of polypharmacy among patients on warfarin therapy appears to peak at age 75, with close to 10 concurrent active prescriptions on average, results from a single-center study showed.

“Beware of polypharmacy with these patients,” Alan Jacobson, MD , said in an interview at the biennial summit of the Thrombosis & Hemostasis Societies of North America. “Anticoagulation tends to be a high-risk area. If you don’t treat, people have strokes. If you treat, they can have bleeds. Warfarin is the number one drug that gets older patients into the ER and admitted. We know that warfarin has a lot of drug-drug interactions.”

The average 75-year-old in the general population takes an average of 4.2 prescription medications, yet little is known about the number of drugs that patients who receive warfarin take, and how this varies with age, according to Dr. Jacobson, a cardiologist who directs the anticoagulant service at the Veterans Affairs Loma Linda (Calif.) Healthcare System.

For example, in the ARISTOTLE trial, patients used a median of six drugs, and 26% of patients used nine or more drugs ( BMJ. 2016 Jun 15;353:i2868 .

In an effort to determine the average and maximum number of concurrent prescription drugs for age-dependent brackets of patients on warfarin, Dr. Jacobson and his associates reviewed the electronic pharmacy records of 1,122 warfarin patients at the VA Loma Linda Healthcare System. They excluded medications that could be obtained over the counter and calculated the average number of concurrent drugs for each of 10 age brackets: under age 50, over age 90, and eight brackets between those limits.

The researchers reported that 9,885 prescriptions were tabulated for the study population, which translated into a per patient average of 8.8 concurrent active prescription drugs, independent of age. They observed an age-dependent increase in the number of concurrent drugs that peaked at 9.9 among patients aged 70-74 years, and tapered off in those older than age 75. One patient in the 70- to 74-year-old age group was on 28 active prescriptions.

“If you’re on 28 pills, your chance of a bleeding complication is high,” Dr. Jacobson said. “We try to be rigorous with all of our patients on education. With these patients, slow the conversation down more. Have a family member come in with them and go into more detail.”

He added that the maximum number of concurrent prescriptions for any single patient in each age bracket tended to be two to three times higher than that of the average patient.

Dr. Jacobson acknowledged certain limitations of the study, including its single-center design and relatively small sample size. There was also no comparison available as to the number of concurrent prescriptions for patients not receiving warfarin. He reported having no financial disclosures.

SOURCE: Jacobson M et al. THSNA 2018. Poster 2 .