A large population-based study from Austria found that fair bowel preparation during screening colonoscopy was associated with more than twice the risk of post-colonoscopy colorectal cancer death compared to excellent preparation.

The study, published in The American Journal of Gastroenterology, analyzed 335,466 screening colonoscopies performed between 2012 and 2022. Researchers found that even "fair" bowel preparation—currently considered adequate by guidelines—was associated with significantly lower adenoma detection rates and higher post-colonoscopy colorectal cancer (PCCRC) mortality.

The investigation documented 242 PCCRC deaths in 1.57 million person-years of follow-up, with death rates varying significantly by preparation quality:

• Excellent preparation: 10.05 deaths per 100,000 person-years
• Good preparation: 13.60 deaths per 100,000 person-years
• Fair preparation: 31.42 deaths per 100,000 person-years
• Poor preparation: 36.01 deaths per 100,000 person-years
• Inadequate preparation: 58.66 deaths per 100,000 person-years

The study revealed distinct patterns in cecal intubation rates based on preparation quality:

• Excellent preparation: 98.31%
• Good preparation: 98.01%
• Fair preparation: 97.59%
• Poor preparation: 90.13%
• Inadequate preparation: 58.56%

The odds of detecting adenomas decreased progressively with worsening bowel preparation quality:

• Good preparation: Odds Ratio (OR) 1.01
• Fair preparation: OR 0.97 
• Poor preparation: OR 0.76 
• Inadequate preparation: OR 0.44

Serrated lesion detection also showed significant decreases with lower preparation quality:

• Good preparation: OR 0.84 
• Fair preparation: OR 0.83
• Poor preparation: OR 0.53
• Inadequate preparation: OR 0.53

Among the colonoscopies analyzed, 37% had excellent preparation, 48% good preparation, 11% fair preparation, 3% poor preparation, and 1% inadequate preparation. The median follow-up period was 4.60 years (95% CI, 4.59-4.62).

The 10-year cumulative CRC mortality was 0.14% in patients with good or excellent bowel preparation compared to 0.41% in those with fair or worse preparation.

The study's limitations included a lack of data on patient risk factors, incident cancers, and complete surveillance colonoscopy information. The median age of participants was 60.0 years, with 50.92% female.

Conflict of interest disclosures can be found in the study.