Clinical study
Improving the quality of anticoagulation of patients with atrial fibrillation in managed care organizations: results of the managing anticoagulation services trial

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Abstract

Purpose

Randomized trials have indicated that well-managed anticoagulation with warfarin could prevent more than half of the strokes related to atrial fibrillation. However, many patients with atrial fibrillation who are eligible for this therapy either do not receive it or are not maintained within an optimal prothrombin time–international normalized ratio (INR) range. We sought to determine whether an anticoagulation service within a managed care organization would be a feasible alternative for providing anticoagulation care.

Subjects and methods

We performed a multi-site randomized trial in six large managed care organizations in the United States. Subjects were aged 65 years or older and had nonvalvular atrial fibrillation. At each site, physician practices were divided into two geographically defined practice clusters; each site was randomly assigned to have one intervention and one control cluster. The intervention cluster received an anticoagulation service that satisfied specifications for high-quality anticoagulation care and was coordinated through the managed care organization. Control clusters continued with their usual provider-based care. We measured the proportion of time that warfarin-treated patients in each of the clusters (intervention and control) were in the target range for the INR at baseline, and again during a follow-up period.

Results

Five of the six selected sites succeeded at developing an anticoagulation service. Patients in the intervention and control clusters had similar demographic characteristics, contraindications to warfarin, and risk factors for stroke. Among patients (n = 144 in the intervention clusters; n = 118 in the control clusters) for whom data were available during the baseline and follow-up periods, the changes in percentages of time in the target range were similar for those in the intervention clusters (baseline: 47.7%; follow-up: 55.6%) and in the control clusters (baseline: 49.1%; follow-up: 52.3%; intervention effect: 5%; 95% confidence interval: –5% to 14%; P = 0.32).

Conclusion

Although it was feasible in a managed care organization to implement anticoagulation services that were tailored to local circumstances, provision of this service did not improve anticoagulation care compared with usual care. The effect of the anticoagulation service was limited by the utilization of the service, the degree to which the referring physician supports strict adherence to recommended target ranges for the INR, and the ability of the anticoagulation service to identify and to respond to out-of-range values promptly.

Section snippets

Design

To identify sites, we obtained a list of managed care organizations with Medicare managed care contracts from the Health Care Financing Administration. Thirty-five of the larger managed care organizations were contacted. We selected six organizations, including four that contracted with independent practices, one that had a staff model organization, and one that incorporated both organizational structures. At each site, two geographically related groups of practices with approximately 200 to

Results

An anticoagulation service meeting the functional specifications for the trial was set up at all six sites. One site was subsequently dropped from the study for failing to meet minimum performance requirements. The remaining five sites enrolled eligible patients throughout the trial, with final enrollments ranging from 70 to 200 patients per clinic. Based on data from the managed care organization administrative files and clinic enrollment lists, the percentage of eligible providers who used

Discussion

We determined that developing an anticoagulation service in a managed care environment was feasible—five of the six sites were able to implement an anticoagulation service consistent with the standard specifications for anticoagulation care. Our results indicate that a properly administered anticoagulation service can successfully manage the anticoagulation of most patients with atrial fibrillation; however, these services did not improve anticoagulation compared with usual care.

The success of

Acknowledgements

We would like to thank Kenneth Goldberg, MD, for programming assistance; Meg McCormack, PA-C, RN, for her work in helping to identify sites and in monitoring the operations of the anticoagulation services; Olivier Rutschmann, MD, MPH, for assistance in the analysis of event data; William Rock, PharmD, for providing the training to the site anticoagulation clinic managers; and Yen-Pin Chiang, PhD, of the Agency for Healthcare Research and Quality and Kim Gilchrist, MD, of DuPont Pharmaceuticals

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    This study was supported by Contract 290-91-0028 from the Agency for Healthcare Research and Quality, and DuPont Pharmaceuticals Company, Wilmington, Delaware.

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