Table 3.
Results for the secondary outcome of percentage of days that adherence was incorrect, among all participants, and stratified by INR at enrollment.
| % incorrect adherence a | Minimally adjusted model b | Fully adjusted model c | ||||
|---|---|---|---|---|---|---|
| n | Median (IQR) | Difference (95% CI) d | P value e | Difference (95% CI) d | P value e | |
| All participants | 0.03 | 0.008 | ||||
| Control | 57 | 23.7 (8.1–40.5) | Referent | Referent | ||
| Lottery | 65 | 12.1 (6.6–25.0) | −7.9 (−14.1, −1.7) | −7.4 (−14.4, −0.3) | ||
| Reminder | 63 | 21.8 (6.9–39.5) | 0.5 (−7.5, 8.5) | −2.0 (−8.2, 4.2) | ||
| Lottery + Reminder | 66 | 17.6 (7.0–43.6) | −3.1 (−10.2, 4.1) | −4.6 (−11.1, 1.9) | ||
| Participants with an in−range INR at enrollmentf | 0.03 | 0.01 | ||||
| Control | 46 | 25.0 (8.1–40.3) | Referent | Referent | ||
| Lottery | 51 | 12.1 (5.9–25.0) | −8.1 (−14.6, −1.6) | −7.5 (−14.7, −0.3) | ||
| Reminder | 49 | 23.5 (9.5–39.5) | 1.2 (−7.6, 10.0) | −1.4 (−7.9, 5.1) | ||
| Lottery + Reminder | 53 | 17.1 (7.0–32.6) | −3.9 (−11.5, 3.7) | −5.0 (−11.7, 1.8) | ||
| Participants with a below-range INR at enrollment f | 0.75 | 0.73 | ||||
| Control | 11 | 16.9 (7.7–42.3) | Referent | Referent | ||
| Lottery | 14 | 14.5 (8.5–26.5) | −7.7 (−25.9, 10.5) | −7.9 (−24.5, 8.8) | ||
| Reminder | 14 | 20.9 (6.1–33.5) | −2.2 (−22.4, 18.1) | −4.6 (−22.5, 13.3) | ||
| Lottery + Reminder | 13 | 34.2 (10.5–44.5) | 0.5 (−19.9, 21.0) | −3.6 (−21.1, 14.0) | ||
IQR, inter-quartile range (25th–75th percentile); CI, confidence interval
Percentage of days that adherence was incorrect, calculated over the entire study period for each participant.
Adjusted for site (Hospital of the University of Pennsylvania or Philadelphia Veterans Affairs Medical Center), INR at enrollment (in range or below range), and month since randomization. Model coefficients transformed back from the square root term so that the reported differences are model based estimates of the mean % incorrect adherence.
Adjusted for site (Hospital of the University of Pennsylvania or Philadelphia Veterans Affairs Medical Center), INR at enrollment (in range or below range), month since randomization, age in years, African American race, completed high school, employment status (working, unemployed, retired, disabled), Medicare insurance, target INR range (2.0–3.0 or 2.5–3.5), and history of diabetes mellitus. Model coefficients transformed back from the square root term so that the reported differences are model based estimates of the mean % incorrect adherence.
Difference corresponds to the estimated difference in average % incorrect adherence relative to the control group.
P values obtained from multivariable Wald test of the null hypothesis that the lottery, reminder, and lottery + reminder differences are all equal to 0.
There was no evidence that odds ratios differed by INR at enrollment (interaction P=0.95).