Table 1.
Univariate and multivariable analysis of associations between clinical and demographic characteristics and use of an erythropoiesis-stimulating agent (ESA) (n = 56 210; 15 346 [27%] with ESA use)*
| Characteristic | No. | ESA use, % | Univariate OR | Multivariable OR (95% CI) |
| Age at diagnosis, y | ||||
| 65–69 | 15 093 | 26.5 | 1.0 | 1.00 (referent) |
| 70–74 | 18 749 | 27.2 | 1.03 | 1.01 (0.96 to 1.07) |
| 75–79 | 13 808 | 28.2 | 1.09 | 1.02 (0.96 to 1.08) |
| ≥80 | 8560 | 27.5 | 1.05 | 0.93 (0.87 to 1.00) |
| Race | ||||
| White | 49 528 | 27.3 | 1.00 | 1.00 (referent) |
| Black | 3337 | 29.5 | 1.12 | 0.99 (0.90 to 1.08) |
| Hispanic | 617 | 28.5 | 1.06 | 0.87 (0.71 to 1.05) |
| Missing or other | 2728 | 23.8 | 0.54 | 0.86 (0.71 to 0.96) |
| Sex | ||||
| Male | 21 809 | 25.9 | 1.00 | 1.00 (referent) |
| Female | 34 401 | 28.1 | 1.11 | 1.22 (1.16 to 1.28) |
| Residence | ||||
| Metropolitan | 51 188 | 27.8 | 1.00 | 1.00 (referent) |
| Nonmetropolitan | 5021 | 22.4 | 0.75 | 0.83 (0.76 to 0.91) |
| Marital status | ||||
| Married | 32 555 | 27.5 | 1.00 | 1.00 (referent) |
| Unmarried or unknown | 21 952 | 26.9 | 0.97 | 0.91 (0.87 to 0.94) |
| Socioeconomic status | ||||
| Lowest (first) quartile | 16 575 | 25.5 | 1.00 | 1.00 (referent) |
| Second quartile | 12 803 | 26.2 | 1.04 | 1.06 (0.99 to 1.13) |
| Third quartile | 12 503 | 28.4 | 1.16 | 1.10 (1.03 to 1.17) |
| Highest (fourth) quartile | 13 466 | 30.3 | 1.27 | 1.10 (1.04 to 1.17) |
| Stage | ||||
| Nonmetastatic | 27 754 | 23.3 | 1.00 | 1.00 (referent) |
| Metastatic | 17 702 | 28.4 | 1.30 | 2.03 (1.92 to 2.13) |
| Both | 10 754 | 35.7 | 1.82 | 3.05 (2.89 to 3.23) |
| Radiation therapy | ||||
| No | 29 108 | 25.1 | 1.00 | 1.00 (referent) |
| Yes | 27 102 | 29.6 | 1.26 | 1.10 (1.05 to 1.15) |
| Comorbidity score | ||||
| 0 | 30 477 | 25.4 | 1.00 | 1.00 (referent) |
| 1 | 15 768 | 28.1 | 1.15 | 1.07 (1.02 to 1.13) |
| >1 | 9965 | 31.7 | 1.36 | 1.13 (1.07 to 1.20) |
| Period | ||||
| 1991–1995 | 14 206 | 7.8 | 1.00 | 1.00 (referent) |
| 1996–1998 | 14 896 | 19.2 | 2.82 | 3.03 (2.81 to 3.27) |
| 1999–2002 | 27 108 | 42.0 | 8.65 | 9.79 (9.11 to 10.52) |
| Tumor site | ||||
| Colon | 13 422 | 17.2 | 1.00 | 1.00 (referent) |
| Breast | 14 024 | 27.4 | 1.82 | 1.74 (1.62 to 1.87) |
| Lung | 16 939 | 32.5 | 2.32 | 1.92 (1.79 to 2.05) |
| Diffuse large B-cell lymphoma | 11 825 | 31.3 | 2.07 | 2.55 (2.38 to 2.72) |
*
Each variable was corrected for the other listed characteristics as well as for the Surveillance, Epidemiology, and End Results site. CI = confidence interval; OR = odds ratio.