Home Coumadin Monitoring is Safe and Cost-Effective

VANCOUVER, British Columbia, June 19 ? Patients on long-term anticoagulation therapy can safely monitor their anticoagulation status and time and money, researchers here reported.

Allowing patients who are on long-term Coumadin (warfarin) therapy to monitor their own international normalized ratios (INRs) and adjust their doses accordingly would result in fewer thrombotic events, major hemorrhagic events, and deaths than if all patients were managed by their physicians or coagulation clinics, the investigators wrote in the June 20 issue of the Canadian Medical Association Journal.

"It has been found that patients who self-manage check their INR more frequently and are able to maintain a greater proportion of INRs within the therapeutic range compared with those whose therapy is monitored by a physician or in an anticoagulation clinic," wrote Dean Regier, Ph.D., and colleagues, of the Vancouver Coastal Health Research Institute and University of British Columbia.

Their study, based on a mathematical model, confirms the results of other studies that have found a benefit for home-based coagulation monitoring.

Last February, for example, researchers at the University of Oxford in England reported in The Lancet that patients who monitor and adjust levels of oral anticoagulant medications on their own can reduce their risk of death from all causes by one-third, and cut the risk of a thromboembolic event in half.

In the current study, Dr. Regier, a health economist, and colleagues, developed a Bayesian Markov model to compare the costs and quality-adjusted life years attributable to either self-management or physician management of anticoagulation in patients on long-term Coumadin therapy for either atrial fibrillation or a mechanical heart valve.

They incorporated into their model five health states: no events, minor hemorrhage, major hemorrhage, thrombotic events, and death. They used data from published studies to calculate the probabilities that patients would move from one health state to another, and drew on Canadian health -are expenditure data from 2003 to determine costs.

They found that over a five-year period, self-management would result in 3.50 fewer thrombotic events per 100 patients. 0.78 fewer major hemorrhagic events, and 0.12 fewer deaths than if the patients' INRs were managed entirely by physicians.

The mean per-patient cost of self-monitoring over five years was higher in the self-management group (all amounts in Canadian dollars) at ,116 (95% confidence interval, ,426-,380), compared with ,127 (95% CI -) for the physician-managed group.

According to the model, the self-management strategy would result in 4.28 quality-adjusted life years (95% CI 4.24-4.30), while physician management would result in 4.21 quality-adjusted life years (95% CI 4.19-4.25). This translates into an incremental quality-adjusted life years gained value of 0.07 (95% CI 0.056-0.084) in favor of self-management.

The incremental cost-effectiveness of self-managed long-term anticoagulation therapy over physician-managed would be ,129 per quality-adjusted life years over five years, the investigators determined.

"Although the threshold of what decision makers are willing to pay for a value judgment, in Canada it is generally accepted that a threshold of ,000 per quality-adjusted-life-year represents good value given scarce health resources," they wrote. "Therefore, over a five-year period, our model suggests that self-management is a cost-effective option for a patient population taking warfarin for a mechanical heart valve or for atrial fibrillation."

The Canadian health care system does not pay for patient self-monitoring of INRs, the authors noted.

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• Home Coumadin Self-Monitoring Proves Workable and Beneficial