TABLE 2.
INR Monitoring, Anticoagulation Clinic Interventions, and Warfarin Dose Adjustments
| Measures | Months 1-3 | Months 4-6 | Months 7-18 | Months 19-30 |
|---|---|---|---|---|
| Duration for Evaluation | 3 months | 3 months | 12 months | 12 months |
| Overalla | ||||
| Number of INR monitoring tests | 8.4 (8.5) (n = 19,086) | 5.9 (6.1) (n = 22,580) | 18.6 (20.1) (n = 24,583) | 18.8 (21.2) (n = 19,955) |
| Number of anticoagulation clinic interventionsb | 7.0 (4.8) (n = 19,603) | 4.9 (3.0) (n = 23,424) | 15.3 (8.9) (n = 25,477) | 15.2 (8.6) (n = 20,563) |
| Number of dose adjustments | 4.0 (3.6) (n = 16,701) | 2.9 (2.8) (n = 15,860) | 6.7 (6.3) (n = 24,437) | 6.7 (6.3) (n = 19,974) |
| Days between INR monitoring | 8.7 (7.7) (n = 16,375) | 17.1 (12.7) (n = 21,926) | 22.1 (17.8) (n = 24,505) | 23.4 (23.4) (n = 19,925) |
| Days between interventions | 9.0 (7.7) (n = 16,332) | 15.9 (11.0) (n = 21,905) | 21.5 (15.8) (n = 24,945) | 22.3 (16.0) (n = 20,147) |
| Days between INR and the next dose adjustment, median (IQR) | 1 (1-4) (n = 15,390) | 1 (1-4) (n = 15,390) | 1 (1-3) (n = 22,887) | 1 (1-3) (n = 18,596) |
| New warfarin usersa | ||||
| Number of INR monitoring tests | 11.4 (8.7) (n = 11,585) | 6.7 (6.1) (n = 10,941) | 18.1 (17.4) (n = 11,456) | 17.4 (16.8) (n = 8,723) |
| Number of anticoagulation clinic interventionsb | 9.6 (4.0) (n = 12,051) | 5.7 (3.2) (n = 11,433) | 15.3 (9.1) (n = 11,964) | 14.6 (8.7) (n = 9,028) |
| Number of dose adjustments | 4.7 (3.7) (n = 10,364) | 3.3 (3.2) (n = 8,396) | 7.0 (6.5) (n = 11,156) | 6.6 (6.2) (n = 8,134) |
| Days between INR monitoring | 7.7 (6.2) (n = 11,255) | 15.2 (11.1) (n = 10,872) | 20.5 (18.1) (n = 11,418) | 22.5 (27.4) (n = 8,697) |
| Days between interventions | 8.0 (6.3) (n = 11,631) | 14.3 (9.6) (n = 10,980) | 19.9 (15.0) (n = 11,606) | 21.2 (15.6) (n = 8,766) |
| Days between INR and the next dose adjustment, median (IQR) | 1 (1-4) (n = 9,815) | 1 (1-4) (n = 9,815) | 1 (1-3) (n = 10,254) | 1 (1-3) (n = 7,401) |
| Experienced warfarin usersa | ||||
| Number of INR monitoring tests | 3.7 (5.7) (n = 7,501) | 5.2 (6.0) (n = 11,639) | 19.0 (22.2) (n = 13,127) | 19.9 (24.0) (n = 11,232) |
| Number of anticoagulation clinic interventionsb | 2.8 (2.6) (n = 7,552) | 4.2 (2.7) (n = 11,991) | 15.3 (8.7) (n = 13,513) | 15.6 (8.5) (n = 11,535) |
| Number of dose adjustments | 2.9 (3.1) (n = 6,337) | 2.5 (2.2) (n = 7,464) | 6.4 (6.1) (n = 13,281) | 6.8 (6.3) (n = 1,840) |
| Days between INR monitoring | 14.4 (11.8) (n = 5,120) | 19.6 (14.0) (n = 11,054) | 23.5 (17.3) (n = 13,087) | 23.9 (20.1) (n = 11,228) |
| Days between interventions | 14.9 (11.5) (n = 4,701) | 17.9 (12.2) (n = 10,925) | 22.8 (16.4) (n = 13,339) | 23.0 (16.2) (n = 11,381) |
| Days between INR and the next dose adjustment, median (IQR) | 1 (1-4) (n = 5,575) | 1 (1-4) (n = 5,575) | 1 (1-3) (n = 12,642) | 1 (1-3) (n = 11,195) |
aAll values are represented as mean (SD) unless otherwise noted.
bIntervention = pharmacist contact with patients, mostly through telephone counseling.
INR = international normalized ratio; IQR = interquartile range; SD = standard deviation.