Sex-specific prevalence of adenomas, advanced adenomas, and colorectal cancer in individuals undergoing screening colonoscopy.

Context: Although some studies have shown that men are at greater age-specific risk for advanced colorectal neoplasia than women, the age for referring patients to screening colonoscopy is independent of sex and usually recommended to be 50 years.

Objective: To determine and compare the prevalence and number needed to screen (NNS) for adenomas, advanced adenomas (AAs), and colorectal carcinomas (CRCs) for different age groups in men and women.

Design, Setting, And Patients: Cohort study of 44,350 participants in a national screening colonoscopy program over a 4-year period (2007 to 2010) in Austria.

Main Outcome Measures: Prevalence and NNS of adenomas, AAs, and CRCs in different age groups for men and women.

Results: The median ages were 60.7 years (interquartile range [IQR], 54.5-67.5 years) for women and 60.6 years (IQR, 54.3-67.6 years) for men, and the sex ratio was nearly identical (51.0% [22,598] vs 49.0% [21,572]). Adenomas were found in 19.7% of individuals screened (95% CI, 19.3%-20.1%; n = 8743), AAs in 6.3% (95% CI, 6.1%-6.5%; n = 2781), and CRCs in 1.1% (95% CI, 1.0%-1.2%; n = 491); NNS were 5.1 (95% CI, 5.0-5.2), 15.9 (95% CI, 15.4-16.5), and 90.9 (95% CI, 83.3-100.0), respectively. Male sex was significantly associated with a higher prevalence of adenomas (24.9% [95% CI, 24.3%-25.4%] vs 14.8% [95% CI, 14.3%-15.2%]; P < .001; unadjusted odds ratio [OR], 1.9 [95% CI, 1.8-2.0]), AAs (8.0% [95% CI, 7.6%-8.3%] vs 4.7% [95% CI, 4.4%-4.9%]; P < .001; unadjusted OR, 1.8 [95% CI, 1.6-1.9]), and CRCs (1.5% [95% CI, 1.3%-1.7%] vs 0.7% [95% CI, 0.6%-0.9%]; P < .001; unadjusted OR, 2.1 [95% CI, 1.7-2.5]). The prevalence of AAs in 50- to 54-year-old individuals was 5.0% (95% CI, 4.4%-5.6%) in men but 2.9% (95% CI, 2.5%-3.4%) in women (adjusted P = .001); the NNS in men was 20 (95% CI, 17.8-22.6) vs 34 in women (95% CI, 29.1-40; adjusted P = .001). There was no statistical significance between the prevalence and NNS of AAs in men aged 45 to 49 years compared with women aged 55 to 59 years (3.8% [95% CI, 2.3%-6.1%] vs 3.9% [95% CI, 3.3%-4.5%] and 26.1 [95% CI, 16.5-44.4] vs 26 [95% CI, 22.5-30.2]; P = .99).

Conclusion: Among a cohort of Austrian individuals undergoing screening colonoscopy, the prevalence and NNS of AAs were comparable between men aged 45 to 49 years and women aged 55 to 59 years.