The Quality of Warfarin Prescribing and Monitoring in Veterans Affairs Nursing Homes


  • The views expressed in this paper are those of the authors, and no official endorsement by the Department of Veteran Affairs is intended or should be inferred.

Address correspondence to Sherrie L. Aspinall, Center for Health Equity Research and Promotion, VA Pittsburgh Healthcare System, 7180 Highland Drive (151C-H), Pittsburgh, PA 15206. E-mail:


OBJECTIVES: To describe the quality of warfarin prescribing and monitoring in Veterans Affairs (VA) nursing homes and to assess the factors associated with maintaining a therapeutic international normalized ratio (INR).

DESIGN: Retrospective cohort.

SETTING: Five VA nursing homes.

PARTICIPANTS: All veterans who received warfarin between January 1 and June 30, 2008, at the nursing homes.

MEASUREMENTS: Using medical records, the percentage of person-time spent in the target INR range, the proportion of patients with INRs in the therapeutic range on 50% or more of their person-days, and the frequency of INR monitoring were estimated. Multivariable logistic regression was used to identify factors associated with maintaining a therapeutic INR 50% or more of the time.

RESULTS: Over 6 months, 160 patients received 10,380 person-days of warfarin. INRs were in the therapeutic range for 55% of the person-days, and 99% of the INR tests were repeated within 4 weeks of the previous result. On an individual level, 49% of patients had INRs in the target range for 50% or more of their person-days. Achieving this outcome was more likely in patients with prevalent warfarin use than with new use (adjusted odds ratio (AOR)=2.86, 95% confidence interval (CI)=1.06–7.72). Conversely, patients with a history of a stroke (AOR=0.38, 95% CI =0.18–0.80) were less likely to have therapeutic INRs for 50% or more of their days.

CONCLUSION: Warfarin appears to be prescribed and monitored effectively in VA nursing home patients. Future studies should focus on increasing time in therapeutic range in patients with poor INR control.