Risk factors for inadequate bowel preparation: A retrospective study of 7931 paired colonoscopy cases with a predictive model

Table 1 Baseline characteristics of the study population, n (%)

Sample size	7931
Age (years)	56.9 ± 13.0
Male sex	4127 (52.0)
Afternoon examination	4377 (55.2)
Hypertension	750 (9.5)
Diabetes mellitus	464 (5.9)
Constipation	96 (1.2)
Prior inadequate preparation	2107 (26.6)
Inpatients	4545 (57.3)

Table 2 Multivariate analysis of risk factors for inadequate bowel preparation

Variable	OR	95%CI	P value	VIF
Age (per 1-year increase)	1.016	1.011-1.022	< 0.001	1.20
Male sex	1.447	1.262-1.660	< 0.001	1.05
Afternoon examination	1.566	1.364-1.799	< 0.001	1.04
Hypertension	1.051	0.839-1.316	0.664	1.32
Diabetes mellitus	1.736	1.358-2.219	< 0.001	1.28
Constipation	1.814	1.071-3.005	0.025	1.06
Prior inadequate preparation	3.526	3.083-4.034	< 0.001	1.10
Inpatient status	0.391	0.357-0.427	< 0.001	1.35

OR: Odds ratio; CI: Confidence interval; VIF: Variance inflation factor.