Is Cognitive Impairment Associated with Inadequate Bowel Preparation for Colonoscopy?

Purpose: Inadequate bowel preparation (IBP) for colonoscopies is associated with missed polyps and cancers, prolonged procedure times, lower colonoscopy completion rates, and need for a repeat procedure. The purposes of this study were to assess: 1) whether impaired cognitive status (measured by an abnormal clock drawing test) was associated with IBP, and 2) the association of participant demographic and clinical characteristics with IBP.

Methods: Cross-sectional cohort study conducted in 3 academic centers. Subjects, 50 to 85 years old, completed 5 stool tests on a single sample and a clock drawing before undergoing a screening or surveillance colonoscopy. Clock drawings were validated by the Mendes-Santos method and Watson method. A generalized linear mixed model was conducted to estimate factors associated with IBP, based on Aronchick bowel preparation score.

Results: The 2,016 participants had a mean age of 63 years (SD = 7.95); 1,274 (63%) were female; 119 (6%) had IBP; and 421 (21%) had an abnormal clock drawing. After controlling for age in the multivariable model, the odds of having an IBP versus adequate were 1.44 (95% CI, 0.94-2.22) for those with an abnormal clock drawing score compared with those with a normal score. The only variable significantly associated with IBP was household income, with an odds of 2.48 (95% CI, 1.56-3.95) for household income of <$40,000 compared with income >$80,000.

Conclusions: Lower household income was associated with greater odds of IBP. The association between an abnormal clock drawing score and IBP was not statistically significant.NCT03264898 (clinicaltrials.gov) - Comparative Effectiveness of FITs with Colonoscopy.