Table 2.
Cox proportional hazards and negative binomial regression analyses of cancer incidence*
| Hazard ratio†(95% CI) | p value | Incidence rate ratio‡(95% CI) | p value | ||
|---|---|---|---|---|---|
| Colorectal cancer | |||||
| Intention-to-treat analysis (n=861, 98 events for hazard ratio analysis) | |||||
| Aspirin vs placebo | 0·65 (0·43–0·97) | 0·035 | 0·58 (0·39–0·87) | 0·0085 | |
| Per-protocol analysis§ (n=509, 67 events) | |||||
| ≥2 years' placebo | 1·0 | .. | 1·0 | .. | |
| ≥2 years' aspirin | 0·56 (0·34–0·91) | 0·019 | 0·50 (0·31–0·82) | 0·0057 | |
| Cumulative aspirin dose¶ (n=861, 98 events) | |||||
| Units of 100 aspirin | 0·98 (0·96–1·00) | 0·079 | 0·98 (0·96–1·00) | 0·032 | |
| Non-colorectal Lynch syndrome cancers | |||||
| Intention-to-treat analysis (n=861, 72 events) | |||||
| Aspirin vs placebo | 0·94 (0·59–1·50) | 0·81 | 1·05 (0·65–1·69) | 0·84 | |
| Per-protocol analysis§ (n=509, 46 events) | |||||
| ≥2 years' placebo | 1·0 | .. | 1·0 | .. | |
| ≥2 years' aspirin | 0·75 (0·42–1·34) | 0·33 | 0·87 (0·48–1·61) | 0·67 | |
| Cumulative aspirin dose¶ (n=861, 72 events) | |||||
| Units of 100 aspirin | 0·98 (0·96–1·01) | 0·20 | 0·99 (0·97-1·02) | 0·50 | |
| All Lynch syndrome cancers | |||||
| Intention-to-treat analysis (n=861, 163 events) | |||||
| Aspirin vs placebo | 0·76 (0·56–1·03) | 0·081 | 0·75 (0·56–1·02) | 0·065 | |
| Per-protocol analysis§ (n=509, 107 events) | |||||
| ≥2 years' placebo | 1·0 | .. | 1·0 | .. | |
| ≥2 years' aspirin | 0·63 (0·43–0·92) | 0·018 | 0·65 (0·44–0·94) | 0·022 | |
| Cumulative aspirin dose¶ (n=861, 163 events) | |||||
| Units of 100 aspirin | 0·98 (0·97–1·00) | 0·033 | 0·98 (0·97–1·00) | 0·040 | |
| All non-Lynch syndrome cancers | |||||
| Intention-to-treat analysis (n=861, 78 events) | |||||
| Aspirin vs placebo | 0·81 (0·52–1·26) | 0·34 | 0·79 (0·49–1·28) | 0·34 | |
| Per-protocol analysis§ (n=509, 56 events) | |||||
| ≥2 years' placebo | 1·0 | .. | 1·0 | .. | |
| ≥2 years' aspirin | 0·81 (0·48–1·37) | 0·43 | 0·71 (0·41–1·22) | 0·21 | |
| Cumulative aspirin dose¶ (n=861, 78 events) | |||||
| Units of 100 aspirin | 0·99 (0·97–1·01) | 0·43 | 0·99 (0·96–1·01) | 0·32 | |
*
Adjusted for age and gender in all participants up to 10 years and up to 20 years in England, Finland, and Wales, randomly assigned to aspirin or placebo.
†
Adjusted for age at consent and gender.
‡
Incidence rate ratio from negative binomial regression adjusted for age at consent and gender.
§
The threshold for 2 years' intervention was consumption of more than 1400 aspirin tablets; rounded from a 2-year total of 1461 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.