Table 1.
Characteristics of the study cohort elderly Medicare beneficiaries with diabetes and incident prostate cancer by metformin use SEER-Medicare linked database, 2007–2010.
| All | Overall | Metformin users | Non-metformin-user | Sig. | |||
|---|---|---|---|---|---|---|---|
| N | % | N | % | N | % | ||
| 2,652 | 100 | 948 | 35.7 | 1,704 | 64.3 | ||
| Predisposing characteristics | |||||||
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| |||||||
| Age at diagnosis, in years | ∗∗∗ | ||||||
| 66–74 | 1,579 | 59.5 | 609 | 64.2 | 970 | 56.9 | |
| 75+ | 1,073 | 40.5 | 339 | 35.8 | 734 | 43.1 | |
| Race/ethnicity | ∗ | ||||||
| Whites | 1,914 | 72.2 | 680 | 71.7 | 1,234 | 72.4 | |
| African American | 323 | 12.2 | 108 | 11.4 | 215 | 12.6 | |
| Hispanic/Latino | 150 | 5.7 | 70 | 7.4 | 80 | 4.7 | |
| Others | 265 | 10.0 | 90 | 9.5 | 175 | 10.3 | |
| Marital status | |||||||
| Unmarried | 222 | 8.4 | 73 | 7.7 | 149 | 8.7 | |
| Married | 1,550 | 58.4 | 581 | 61.3 | 969 | 56.9 | |
| Divorced/separated | 393 | 14.8 | 136 | 14.3 | 257 | 15.1 | |
| Others | 487 | 18.4 | 158 | 16.7 | 329 | 19.3 | |
|
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| Enabling characteristics | |||||||
|
| |||||||
| Quartile of median census of 2000 income | ∗ | ||||||
| $7–$34,522 | 664 | 25.0 | 265 | 28.0 | 399 | 23.4 | |
| $34,523–46,224 | 664 | 25.0 | 243 | 25.6 | 421 | 24.7 | |
| $46,229–62,764 | 664 | 25.0 | 229 | 24.2 | 435 | 25.5 | |
| $62,767–200,008 | 660 | 24.9 | 211 | 22.3 | 449 | 26.3 | |
| Quartile of median census of 2000 education | |||||||
| 0–8.52 | 666 | 25.1 | 222 | 23.4 | 444 | 26.1 | |
| 8.53–15.16 | 655 | 24.7 | 229 | 24.2 | 426 | 25.0 | |
| 15.17–26.09 | 664 | 25.0 | 248 | 26.2 | 416 | 24.4 | |
| 26.1–100 | 667 | 25.2 | 249 | 26.3 | 418 | 24.5 | |
| PSA screening | |||||||
| Yes | 2,415 | 91.1 | 872 | 92.0 | 1,543 | 90.6 | |
| No | 237 | 8.9 | 76 | 8.0 | 161 | 9.4 | |
| Visit to a PCP | |||||||
| Yes | 1,858 | 70.1 | 672 | 70.9 | 1,186 | 69.6 | |
| No | 794 | 29.9 | 276 | 29.1 | 518 | 30.4 | |
| Statin use | ∗∗∗ | ||||||
| Yes | 1,576 | 59.4 | 656 | 69.2 | 920 | 54.0 | |
| No | 1,076 | 40.6 | 292 | 30.8 | 784 | 46.0 | |
| Insulin | ∗∗∗ | ||||||
| Yes | 102 | 3.8 | 62 | 6.5 | 40 | 2.3 | |
| No | 2,550 | 96.2 | 886 | 93.5 | 1,664 | 97.7 | |
|
| |||||||
| External environment characteristics | |||||||
|
| |||||||
| SEER-regions | ∗∗ | ||||||
| Northeast | 487 | 18.4 | 146 | 15.4 | 341 | 20.0 | |
| South | 570 | 21.5 | 223 | 23.5 | 347 | 20.4 | |
| North-central | 351 | 13.2 | 112 | 11.8 | 239 | 14.0 | |
| West | 1,244 | 46.9 | 467 | 49.3 | 777 | 45.6 | |
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| Need characteristics | |||||||
|
| |||||||
| DCSI quartile | ∗∗ | ||||||
| 0 to 0 | 846 | 31.9 | 305 | 32.2 | 541 | 31.7 | |
| 1 to 1 | 476 | 17.9 | 195 | 20.6 | 281 | 16.5 | |
| 2 to 3 | 811 | 30.6 | 297 | 31.3 | 514 | 30.2 | |
| 4 to 13 | 519 | 19.6 | 151 | 15.9 | 368 | 21.6 | |
Notes: based on the data of 2,652 elderly men aged 66 years and older diagnosed with prostate cancer between 2008 and 2009 using a surveillance, epidemiology, and end-results- (SEER-) Medicare linked Part D data. Significant group differences by metformin use are based on chi-square tests. % represented in the column is row percentages.
DCSI: diabetes complication severity index; PCP: primary care physician; PSA: prostate specific antigen; Sig.: level of significance. ∗∗∗ p < 0.001; ∗∗0.001 ≤ p < 0.01; ∗0.01 ≤ p < 0.05.