Table 2.
Cox proportional hazards analysis and Poisson regression for colorectal cancer, non-colorectal Lynch syndrome cancers, and all Lynch syndrome cancers (adjusted for sex) in participants randomly assigned to aspirin or aspirin placebo
|
Hazard ratio |
Incidence rate ratio† |
||||
|---|---|---|---|---|---|
| 95% CI* | p value | 95% CI | p value | ||
| Colorectal cancer | |||||
| Intention-to-treat analysis | |||||
| Aspirin versus aspirin placebo | 0·63 (0·35–1·13) | 0·12 | 0·56 (0·32–0·99) | 0·05 | |
| Per-protocol analysis | |||||
| ≥2 years' aspirin placebo‡ | 1·0 | .. | 1·0 | .. | |
| <2 years' aspirin placebo‡ | 0·62 (0·25–1·52) | 0·30 | 0·72 (0·32–1·59) | 0·41 | |
| <2 years' aspirin‡ | 1·07 (0·47–2·41) | 0·87 | 0·90 (0·42–1·91) | 0·77 | |
| ≥2 years' aspirin‡ | 0·41 (0·19–0·86) | 0·02 | 0·37 (0·18–0·78) | 0·008 | |
| Cumulative aspirin dose | |||||
| Units of 100 aspirin§ | 0·97 (0·94–1·00) | 0·06 | 0·97 (0·94–1·00) | 0·03 | |
| Non-colorectal Lynch syndrome cancers | |||||
| Intention-to-treat analysis | |||||
| Aspirin versus aspirin placebo | 0·63 (0·34–1·19) | 0·16 | 0·63 (0·34–1·16) | 0·14 | |
| Per-protocol analysis | |||||
| ≥2 years' aspirin placebo‡ | 1·0 | .. | 1·0 | .. | |
| <2 years' aspirin placebo‡ | 0·96 (0·40–2·34) | 0·94 | 0·82 (0·35–1·96) | 0·66 | |
| <2 years' aspirin‡ | 1·11 (0·46–2·68) | 0·82 | 0·90 (0·38–2·14) | 0·81 | |
| ≥2 years' aspirin‡ | 0·47 (0·21–1·06) | 0·07 | 0·49 (0·23–1·05) | 0·07 | |
| Cumulative aspirin dose | |||||
| Units of 100 aspirin§ | 0·96 (0·93–1·00) | 0·03 | 0·96 (0·93–1·00) | 0·03 | |
| All Lynch syndrome cancers | |||||
| Intention-to-treat analysis | |||||
| Aspirin versus aspirin placebo | 0·65 (0·42–1·00) | 0·05 | 0·59 (0·39–0·90) | 0·01 | |
| Per-protocol analysis | |||||
| ≥2 years' aspirin placebo‡ | 1·0 | .. | 1·0 | .. | |
| <2 years' aspirin placebo‡ | 0·79 (0·42–1·49) | 0·47 | 0·76 (0·43–1·37) | 0·36 | |
| <2 years' aspirin‡ | 1·13 (0·62–2·06) | 0·69 | 0·90 (0·51–1·59) | 0·71 | |
| ≥2 years' aspirin‡ | 0·45 (0·26–0·79) | 0·005 | 0·42 (0·25–0·72) | 0·001 | |
| Cumulative aspirin dose | |||||
| Units of 100 aspirin§ | 0·97 (0·95–0·99) | 0·007 | 0·96 (0·94–0·99) | 0·002 | |
Cox proportional Hazards analysis based on 48 participants with colorectal cancer (including 53 cancer diagnoses), 40 cases of non-colorectal Lynch syndrome cancer, and 86 participants with Lynch syndrome cancers (93 cancer diagnoses).
Incidence rate ratio from Poisson regression.
The threshold for 2 years' intervention was consumption of more than 1400 aspirin tablets; rounded down from a 2-year total of 1461 tablets to allow for early scheduling of the exit colonoscopy or occasional missed dosage.
Units of 100 aspirin=total number of aspirin taken divided by 100.