Table 3.
Results of conditional logit regression analysis by group
| All patients | Lung cancer patients | Colorectal cancer patients | ||||||
|---|---|---|---|---|---|---|---|---|
| Attributes | Levels | Coefficient (95% CI) | RI | Coefficient (95% CI) | RI | Coefficient (95% CI) | RI | p valueb |
| Time in a scanner | Minutes | − 0.002 (− 0.007, 0.002)a | – | − 0.008 (− 0.014, − 0.002) | 0.04 | 0.005 (− 0.002, 0.012)a | – | 0.01 |
| Time to diagnosis | Weeks | − 0.355 (− 0.411, − 0.300) | 1.42 | − 0.372 (− 0.449, − 0.295) | 1.49 | − 0.349 (− 0.432, − 0.265) | 1.40 | 0.70 |
| Radiation dose | Risk of cancer (/1000) | − 0.421 (− 0.521, − 0.320) | 0.84 | − 0.413 (− 0.551, − 0.274) | 0.83 | − 0.436 (− 0.587, − 0.286) | 0.87 | 0.83 |
| Number of additional scans | Number | − 0.192 (− 0.299, − 0.084) | 0.38 | − 0.179 (− 0.330, − 0.028) | 0.36 | − 0.224 (− 0.382, − 0.067) | 0.45 | 0.69 |
| Accuracy | Percentage | 0.128 (0.107, 0.150) | 1.28 | 0.109 (0.079, 0.138) | 1.09 | 0.156 (0.122, 0.190) | 1.56 | 0.03 |
| Need for whole body and head to be in a scanner | No | – | – | – | – | – | – | |
| Yes | 0.020 (− 0.129, 0.170)a | 0.017 (−0.190, 0.224)a | − 0.007 (− 0.233, 0.220)a | 0.88 | ||||
| Observations/respondents | 2362/138 | 1230/72 | 1132/66 | 0.02 | ||||
| Likelihood ratio χ2 (p value) | 445.5 (< 0.01) | 221.9 (< 0.01) | 238.9 (< 0.01) | |||||
NB: Different attributes do not have the same unit of change so cannot be directly compared with one another
CI, confidence interval; RI, relative importance (see text); RI is calculated for attributes with coefficients that were significantly different from zero
aCoefficient not significantly different from zero; all other coefficients significant at p value < 0.05
bp values are from χ2 tests that coefficients are equal for lung cancer and colorectal cancer patients. p values < 0.05 indicate coefficients are significantly different between groups. p value in the bottom row is for joint test across all coefficients