TABLE 2.
Multivariate Cox Proportional Hazards Analysis of Variable Association With Time to Discontinuation of Rosiglitazone After May 21, 2007 Safety Advisory in Black and White Medicare Fee-for-Service Enrollees (n = 45,274)
| Variables | Total (N) | Cases *(N) | Follow-up Time (Person-Years) |
Crude Difference in Median Time to Discontinuation (d) |
Adjusted HR (95% CI)† |
|---|---|---|---|---|---|
| Race | |||||
| Black (reference) | 7862 | 5386 | 4387 | — | — |
| White | 37,412 | 25,105 | 20,787 | 12 | 0.92 (0.88, 0.95) |
| Personal income | |||||
| Not low (reference) | 27,451 | 19,403 | 15,374 | — | — |
| Low | 17,823 | 11,088 | 9799 | 31 | 0.84 (0.81, 0.86) |
| SES index score quintile | |||||
| Quintile 5, lowest (reference) | 9560 | 6348 | 5340 | — | — |
| Quintile 1, highest | 7784 | 5506 | 4337 | −30 | 1.05 (1.00, 1.11) |
| Quintile 2 | 8281 | 5589 | 4578 | −15 | 0.98 (0.88, 1.03) |
| Quintile 3 | 10,390 | 6939 | 5773 | −7 | 0.98 (0.96, 1.03) |
| Quintile 4 | 9259 | 6109 | 5146 | −1 | 0.97 (0.97, 1.02) |
| Sex | |||||
| Female (reference) | 28,149 | 18,970 | 15,676 | — | — |
| Male | 17,125 | 11,521 | 9497 | 8 | 0.96 (0.93, 0.99) |
| Age group (y) | |||||
| 65–69 (reference) | 14,300 | 9989 | 8096 | — | — |
| 70–74 | 12,009 | 8228 | 6763 | 6.5 | 0.96 (0.93, 1.00) |
| 75–79 | 9161 | 6185 | 5094 | 0.5 | 0.94 (0.91, 0.98) |
| 80–84 | 5866 | 3789 | 3185 | 15.5 | 0.92 (0.88, 0.97) |
| ≥ 85 | 3938 | 2300 | 2035 | 34.5 | 0.83 (0.78, 0.88) |
| US Census division | |||||
| New England (reference) | 2144 | 1472 | 1186 | — | — |
| Middle Atlantic | 6854 | 4932 | 3826 | −19.5 | 1.10 (1.02, 1.18) |
| East North Central | 6312 | 4151 | 3498 | 28.5 | 0.93 (0.87, 1.01) |
| West North Central | 3346 | 2014 | 1859 | 67.5 | 0.79 (0.73, 0.86) |
| South Atlantic | 9758 | 6740 | 5438 | 2.5 | 0.99 (0.92, 1.07) |
| East South Central | 4266 | 2695 | 2377 | 34.5 | 0.86 (0.79, 0.94) |
| West South Central | 4815 | 3210 | 2665 | 14.5 | 0.94 (0.86, 1.02) |
| Mountain | 2338 | 1559 | 1295 | 32.5 | 0.95 (0.87, 1.04) |
| Pacific | 4200 | 2859 | 2328 | 4.5 | 0.98 (0.90, 1.06) |
| Cardiovascular (CV) disease | |||||
| History of CV disease (reference) | 10,247 | 7044 | 5633 | — | — |
| No history of CV disease | 35,027 | 23,447 | 19,540 | 24 | 0.90 (0.87, 0.94) |
| Medication adherence | |||||
| Low adherence (reference) (MPR <1) | 25,903 | 18,141 | 14,575 | — | — |
| High adherence (MPR ≥ 1) | 19,371 | 12,350 | 10,599 | 38 | 0.88 (0.85, 0.91) |
| Health service utilization | |||||
| ≤ 2 Outpatient visits (reference) | 27,359 | 18,084 | 15,180 | — | — |
| > 2 Outpatient visits | 17,915 | 12,407 | 9993 | −26 | 1.05 (1.02, 1.09) |
| Receipt of non-TZD DM medication‡ | |||||
| Yes (reference) | 29,730 | 20,504 | 16,597 | — | — |
| No | 15,544 | 9987 | 8576 | 26 | 0.89 (0.86, 0.92) |
| Provider type | |||||
| Endocrinology/ Cardiology (reference) | 2198 | 1588 | 1228 | — | — |
| Other | 43,076 | 28,903 | 23,945 | 25.5 | 0.95 (0.89, 1.02) |
Cases defined as enrollees not censored who discontinue rosiglitazone before the end of study period.
We fit Cox-proportional hazard models to adjust for the selected covariates; confidence intervals that do not cross 1 are significant at P < 0.05; hazard ratio (HR) < 1 implies later discontinuation than comparator group and HR > 1 implies earlier discontinuation than comparator group.
Receipt of at least 1 claim for a nonthiazolidinedione oral diabetic medication in the baseline period before the May 21, 2007 advisory.
CI indicates confidence interval; d, days; DM, diabetes mellitus; HR, hazard ratio; MPR, medication possession ratio; non-TZD, a medication not in the thiazolidinedione class; SES, socioeconomic status; y, years.