Impact of an extended International Normalized Ratio follow-up interval on healthcare use among veteran patients on stable warfarin doses

• Published in: American journal of health-system pharmacy Vol. 76; no. 22; pp. 1848 - 1852
• Main Authors: Margolis, Amanda R, Porter, Andrea L, Staresinic, Carla E, Ray, Cheryl A
• Format: Journal Article
• Language: English
• Published: England Copyright Oxford University Press 30.10.2019; Oxford University Press
• Subjects: Aged; Aged, 80 and over; Anticoagulants - administration & dosage; Anticoagulants - therapeutic use; Clinical Research Reports; Cohort Studies; Drug Monitoring; Emergency Medical Services - statistics & numerical data; Female; Follow-Up Studies; Hospitalization - statistics & numerical data; Humans; International Normalized Ratio; Male; Middle Aged; Patient Acceptance of Health Care; Pharmacy Service, Hospital; Prospective Studies; Triage; Warfarin - administration & dosage; Warfarin - therapeutic use; International Normalized Ratio; health services; anticoagulation; drug monitoring; warfarin
• ISSN: 1079-2082; 1535-2900
• DOI: 10.1093/ajhp/zxz209

To analyze the impact of a 12-week extended International Normalized Ratio (INR) follow-up interval on healthcare use. A prospective cohort study of the use of an extended INR follow-up interval of up to 12 weeks was conducted over 2 years in a pharmacist-managed anticoagulation clinic. A detailed protocol was used to extend the INR follow-up interval to 5-6 weeks and then 7-8 weeks and 11-12 weeks. The number of planned and unplanned anticoagulation encounters, procedures requiring warfarin interruption, telephone triage phone calls, emergency department visits, and hospitalizations were collected. A post hoc subanalysis was also completed on participants who were scheduled for 4 consecutive 12-week intervals. Compared to baseline, at 12 months there was a mean decrease in planned anticoagulation encounters of 2.24 visits (p < 0.001) among 44 participants. From 12 to 24 months compared to baseline, there was a mean decrease in planned anticoagulation encounters of 3.13 visits (p < 0.001) and an increase of 0.54 unplanned anticoagulation encounters (p = 0.04) among 39 participants. The remainder of healthcare use variables were not statistically significantly different from baseline at any time point. Of the 15 participants scheduled for 4 consecutive 12-week intervals, there was a decrease from baseline of approximately 5 visits over the course of a year (p < 0.001). An extended INR follow-up interval appears to decrease anticoagulation healthcare use without an increase in acute healthcare use. While this intervention could be cost-effective, institutions need to consider safety, efficacy, and feasibility prior to implementation.