Table 3. Results of Intention-to-Treat Analysis on CRC Incidence and Mortality After Sigmoidoscopy or Colonoscopy Screeninga.
| CRC | Distal CRC | Proximal CRC | All CRC | |||
|---|---|---|---|---|---|---|
| As observed in sigmoidoscopy trials, rate ratio (95% CI) | As observed in sigmoidoscopy trials, rate ratio (95% CI) | As estimated for colonoscopy, rate ratio (95% CI) | As observed in sigmoidoscopy trials, rate ratio (95% CI) | As estimated for colonoscopy, rate ratio (95% CI) | Colonoscopy screening compared with sigmoidoscopy, additional reduction (95% CI)b | |
| Incidence | ||||||
| All individuals | 0.66 (0.62-0.71) | 0.94 (0.88-1.01) | 0.76 (0.70-0.83) | 0.77 (0.74-0.81) | 0.70 (0.66-0.75) | 6.9 (6.0-7.9) |
| Women | 0.72 (0.65-0.80) | 1.00 (0.90-1.10) | 0.84 (0.74-0.94) | 0.85 (0.79-0.91) | 0.77 (0.70-0.85) | 8.4 (6.2-10.5) |
| Men | 0.64 (0.59-0.69) | 0.90 (0.81-0.99) | 0.71 (0.64-0.79) | 0.72 (0.68-0.77) | 0.66 (0.62-0.72) | 5.8 (4.8-6.9) |
| Mortality | ||||||
| All individuals | 0.64 (0.57-0.72) | 0.92 (0.81-1.05) | 0.70 (0.60-0.81) | 0.76 (0.70-0.83) | 0.68 (0.61-0.76) | 7.6 (5.7-9.6) |
| Women | 0.79 (0.64-0.97) | 0.94 (0.78-1.13) | 0.79 (0.64-0.98) | 0.87 (0.76-0.99) | 0.80 (0.67-0.96) | 7.8 (3.1-12.5) |
| Men | 0.58 (0.49-0.67) | 0.91 (0.76-1.08) | 0.66 (0.54-0.80) | 0.70 (0.63-0.78) | 0.62 (0.54-0.71) | 7.3 (5.3-9.4) |
Abbreviation: CRC, colorectal cancer.
a
Sigmoidoscopy screening effects are estimated from pooled data from the 4 randomized sigmoidoscopy screening trials. Colonoscopy screening effects are estimated from the same data, but with the screening effect in the proximal colon (by colonoscopy) assumed to be similar to the sigmoidoscopy screening effect in the distal colorectum.
b
Numbers are percentage points.