Association between body mass index and quality of split bowel preparation.

Background & Aims: Little is known about the association between obesity and bowel preparation. We investigated whether body mass index (BMI) is an independent risk factor for inadequate bowel preparation in patients who receive split preparation regimens.

Methods: We performed a retrospective study of data from 2163 consecutive patients (mean age, 60.6 ± 10.5 y; 93.8% male) who received outpatient colonoscopies in 2009 at the Veterans Affairs Medical Center in Indianapolis, Indiana. All patients received a split preparation, categorized as adequate (excellent or good, based on the Aronchick scale) or inadequate. We performed a multivariable analysis to identify factors independently associated with inadequate preparation.

Results: Bowel preparation quality was inadequate for 44.2% of patients; these patients had significantly higher mean BMIs than patients with adequate preparation (31.2 ± 6.5 vs 29.8 ± 5.9, respectively; P < .0001) and Charlson comorbidity scores (1.5 ± 1.6 vs 1.1 ± 1.4; P < .0001). Independent risk factors for inadequate preparation were a BMI of 30 kg/m(2) or greater (odds ratio [OR], 1.46; 95% confidence interval [CI], 1.21-1.75; P < .0001), use of tobacco (OR, 1.28; 95% CI, 1.07-1.54; P = .0084) or narcotics (OR, 1.28; 95% CI, 1.04-1.57; P = .0179), hypertension (OR, 1.30; 95% CI, 1.07-1.57; P = .0085), diabetes (OR, 1.38; 95% CI, 1.12-1.69; P = .0021), and dementia (OR, 3.02; 95% CI, 1.22-7.49; P = .0169).

Conclusions: BMI is an independent factor associated with inadequate split bowel preparation for colonoscopy. Additional factors associated with quality of bowel preparation include diabetes, hypertension, dementia, and use of tobacco and narcotics. Patients with BMIs of 30 kg/m(2) or greater should be considered for more intensive preparation regimens.