Good quality of oral anticoagulation treatment in general practice using international normalised ratio point of care testing

INTRODUCTION: Oral anticoagulation treatment (OACT) with warfarin is common in general practice. Increasingly, international normalised ratio (INR) point of care testing (POCT) is being used to manage patients. The aim of this study was to describe and analyse the quality of OACT with warfarin in general practice in the Capital Region of Denmark using INR POCT.

METHODS: A total of 20 general practices, ten single-handed and ten group practices using INR POCT, were randomly selected to participate in the study. Practice organisation and patient characteristics were recorded. INR measurements were collected retrospectively for a period of six months. For each patient, time in therapeutic range (TTR) was calculated and correlated with practice and patient characteristics using multilevel linear regression models.

RESULTS: We identified 447 patients in warfarin treatment in the 20 practices using POCT (median = 19 patients; range: 6-55). The mean TTR for all patients was 69.3% (standard deviation (SD) = 24%), and for all practices the mean TTR was 67.3% (SD = 6.7%). The TTR in single-handed practices was lower than in group practices, 64.6% (SD = 8.0%) and 70.0% (SD = 3.6%), respectively; but the difference was not significant (4.2 percentage points (pp); 95% confidence interval (CI): -0.8-9.2). Short sampling intervals, e.g. 10-20 days (-11 pp; 95% CI: -16-6)) and lack of diagnostic coding (-11.8 pp; 95% CI: -19.9-3.7) were correlated with a low TTR.

CONCLUSION: In our study most of the general practices using INR POCT in the management of patients in warfarin treatment provided good quality of care. Sampling interval and diagnostic coding were significantly correlated with treatment quality.