Multivariate logistic regression with surgical margins status (2011–2014, n=31 593) and 90 days re-excision (2009–2014, n=77 965) as dependent variables
| Surgical margins (0=margins free, 1=focally positive) | 90 days re-excision rate (0=no re-excision, 1=re-excision) | |||
| OR | 95% CI | OR | 95% CI | |
| Annual hospital volume (rolling three-year average) | ||||
| <75 | 0.815 | 0.607 to 1.094 | 1.060 | 0.818 to 1.374 |
| 75–99 | 0.874 | 0.740 to 1.033 | 1.026 | 0.870 to 1.211 |
| 100–149 | 1 | 1 | ||
| 150–199 | 0.847 | 0.656 to 1.094 | 0.864 | 0.688 to 1.086 |
| 200–249 | 0.869 | 0.674 to 1.119 | 0.857 | 0.708 to 1.038 |
| 250 or more | 0.847 | 0.626 to 1.146 | 0.807 | 0.601 to 1.083 |
| Number of other hospitals in the proximity of hospital i in 30 km radius | ||||
| 0–3 | 1 | 1 | ||
| 4 or more | 0.945 | 0.806 to 1.110 | 0.875 | 0.755 to 1.013 |
| Age at diagnosis (years) | ||||
| 15–29 | 1 | 1 | ||
| 30–44 | 1.943 | 0.923 to 4.089 | 0.927 | 0.545 to 1.579 |
| 45–59 | 1.920 | 0.886 to 4.161 | 0.764 | 0.453 to 1.286 |
| 60–74 | 1.768 | 0.804 to 3.891 | 0.605 | 0.361 to 1.013 |
| 75+ | 1.907 | 0.868 to 4.192 | 0.547* | 0.319 to 0.937 |
| Socioeconomic status | ||||
| Low | 1 | 1 | ||
| Middle | 0.947 | 0.838 to 1.069 | 0.992 | 0.901 to 1.091 |
| High | 0.989 | 0.858 to 1.141 | 1.081 | 0.965 to 1.211 |
| Surgical procedure | ||||
| Lumpectomy | N/A | 1 | ||
| Mastectomy | N/A | 0.033** | 0.0236 to 0.0447 | |
| Morphology | ||||
| Ductal | 1 | 1 | ||
| Lobular | 2.941** | 2.637 to 3.281 | 2.161** | 1.959 to 2.383 |
| Other | 1.405** | 1.248 to 1.582 | 1.579** | 1.452 to 1.717 |
| TNM stage | ||||
| 1 | 1 | 1 | ||
| 2 | 2.216** | 2.019 to 2.433 | 1.552** | 1.441 to 1.672 |
| 3 | 5.016** | 4.245 to 5.927 | 2.837** | 2.454 to 3.279 |
| Tumour grade | ||||
| I | 1 | 1 | ||
| II | 1.173** | 1.061 to 1.297 | 1.318** | 1.205 to 1.442 |
| III or undifferentiated | 0.928 | 0.838 to 1.027 | 1.159* | 1.030 to 1.303 |
| Unknown | 1.108 | 0.923 to 1.331 | 1.361** | 1.128 to 1.642 |
| Hospital type | ||||
| General | 1 | 1 | ||
| Tertiary/University | 1.131 | 0.919 to 1.392 | 1.163 | 0.985 to 1.374 |
Also corrected for year of surgery.
Adjusted explained variance: surgical margins: 6%, 90 days re-excision: 14%.
Surgical margins were only calculated for patients who underwent a lumpectomy. Therefore, the variable ‘surgical procedure’ has been excluded from this analysis.
*P<0.05, **p<0.01.
TNM, tumour, node, metastases.