Prompt repeat testing after out-of-range inr values a quality indicator for anticoagulation care

Background: Improved control of oral anticoagulation reduces adverse eventsA program of quality measurement is needed for oral anticoagulationThe interval until the next test after an out-of-range International Normalized Ratio (INR) value (the "follow-up interval") could serve as a process of care measureMethods and Results: We studied 104 451 patients cared for by 100 anticoagulation clinics in the Veterans Health Administration (VA)For each site, we computed the average follow-up interval after low (≤1.5) or high (≥4.0) INROur outcome was each site's average anticoagulation control, measured by percent time in therapeutic range (TTR); 59 837 patients (57%) contributed to the low INR analysis, 37 697 (36%) contributed to the high INR analysis, and all patients contributed to the dependent variable (mean site TTR)After a low INR, site mean follow-up interval ranged from 10 to 24 daysLonger follow-up intervals were associated with worse site-level control (1.04% lower for each additional day, P<0.001)After a high INR, site mean follow-up interval ranged from 6 to 18 days, with longer follow-up intervals associated with worse site-level control (1.12% lower for each additional day, P<0.001)These relationships were somewhat attenuated but still highly statistically significant when the proportion of INR values in-range was used as the dependent variable rather than TTRConclusions: Prompt repeat testing after out-of-range INR values is associated with better anticoagulation control at the site level and could be an important part of a quality improvement effort for oral anticoagulation