Table 4.
Multivariate Analyses of the Likelihood of Ordering Five Genetic Tests, by Provider and Practice Characteristics
| Variables | KRAS | BRAF | MSI/IHC | Germline | Oncotype DX |
|---|---|---|---|---|---|
| Family history | |||||
| None | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Weak | 1.48 (0.75 to 2.92) | 1.39 (0.52 to 3.72) | 1.27 (0.72 to 2.22) | 2.69 (1.36 to 5.34) | 1.18 (0.65 to 2.14) |
| Strong | 1.69 (0.87 to 3.30) | 4.22 (1.77 to 10.06) | 3.87 (2.07 to 7.22) | 40.82 (18.27 to 91.21) | 1.11 (0.62 to 1.99) |
| Age of physician (for each year) | 1.03 (1.00 to 1.06) | 1.02 (0.98 to 1.06) | 0.98 (0.96 to 1.01) | 0.98 (0.95 to 1.01) | 1.00 (0.98 to 1.03) |
| Sex of physician | |||||
| Male | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Female | 1.65 (0.86 to 3.17) | 1.58 (0.69 to 3.59) | 1.44 (0.78 to 2.65) | 1.05 (0.52 to 2.12) | 1.13 (0.62 to 2.05) |
| Country of medical school graduation | |||||
| United States or Canada | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Non–United States or non-Canada | 2.16 (1.17 to 3.99) | 3.12 (1.51 to 6.47) | 0.74 (0.42 to 1.31) | 1.41 (0.72 to 2.79) | 1.44 (0.81 to 2.55) |
| Teaching frequency | |||||
| ≤ 5 d/mo | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| ≥ 6 d/mo | 1.20 (0.59 to 2.43) | 0.69 (0.26 to 1.85) | 1.02 (0.54 to 1.93) | 0.60 (0.27 to 1.31) | 1.24 (0.66 to 2.34) |
| No. of new patients with CRC per month | |||||
| 1-5 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| ≥ 6 | 0.87 (0.42 to 1.76) | 0.69 (0.27 to 1.80) | 1.14 (0.61 to 2.16) | 1.30 (0.64 to 2.66) | 0.91 (0.48 to 1.75) |
| Patients with CRC in physician’s practice, % | |||||
| < 25 | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| ≥ 25 | 1.44 (0.74 to 2.78) | 2.39 (1.08 to 5.29) | 1.16 (0.61 to 2.19) | 1.42 (0.70 to 2.88) | 0.77 (0.41 to 1.45) |
| Practice setting | |||||
| Office or hospital | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| HMO, VA, or government | 0.86 (0.44 to 1.65) | 0.60 (0.25 to 1.42) | 0.77 (0.44 to 1.36) | 0.59 (0.30 to 1.15) | 0.35 (0.19 to 0.63) |
| Clinical compensation | |||||
| Nonproductivity-based | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) | 1.00 (reference) |
| Fee-for-service or productivity-based | 1.93 (1.02 to 3.66) | 1.31 (0.61 to 2.85) | 0.82 (0.46 to 1.45) | 1.20 (0.63 to 2.30) | 2.04 (1.17 to 3.55) |
NOTE. All data are given as odds ratio (95% CI) unless otherwise noted.
Abbreviations: CRC, colorectal cancer; HMO, health maintenance organization; MSI/IHC, microsatellite instability and/or immunohistochemistry for mismatch repair proteins; VA, Veterans Affairs.