Risk factors for inadequate bowel preparation before colonoscopy: A retrospective cohort study

Table 1 Univariate analysis of patients’ basic data (n = 484), mean ± SD/n (%)

	Successful bowel preparation (n = 359)	Poor bowel preparation (n = 125)	t/χ2 value	P value
Age	50.23 ± 1.27	53.77 ± 1.19	-1.558	0.120
BMI (kg/m2)	24.53 ± 0.23	24.85 ± 0.28	-0.744	0.458
Gender			7.767	0.005a
Male	175 (48.7)	79 (63.2)
Female	184 (51.3)	46 (36.8)
Educational level			5.174	0.395
Primary school or below	9 (2.5)	2 (1.6)
Middle school	55 (15.3)	21 (16.8)
High school/vocational school	59 (16.4)	31 (24.8)
Associate degree	51 (14.2)	16 (12.8)
Bachelor’s degree	140 (39.0)	41 (32.8)
Graduate degree or above	45 (12.5)	14 (11.2)
Constipation	81 (22.6)	28 (22.4)	0.001	0.970
Hypertension	84 (23.4)	41 (32.8)	4.278	0.039a
Diabetes mellitus	39 (10.9)	29 (23.2)	11.685	< 0.001a
Coronary artery disease	29 (8.1)	25 (20.0)	13.295	< 0.001a
Hyperlipidemia	70 (19.5)	44 (35.2)	12.695	< 0.001a
Cerebrovascular disease	10 (2.8)	7 (5.6)	2.167	0.141
Hypothyroidism	6 (1.7)	6 (4.8)	3.754	0.053
History of psychiatric medication use	5 (1.4)	3 (2.4)	0.579	0.431
Liver cirrhosis	0 (0)	3 (2.4)	8.670	0.017a
History of colorectal surgery	10 (2.8)	16 (12.8)	18.292	< 0.001a
History of abdominopelvic surgery (excluding colorectal surgery)	76 (21.2)	22 (17.6)	0.732	0.392
Difficulty walking	7 (1.9)	5 (4.0)	1.612	0.204

^aP < 0.05.

BMI: Body mass index.

Table 2 Analysis of factors related to intestinal preparation in patients (n = 484), mean ± SD/n (%)

	Successful bowel preparation (n = 359)	Poor bowel preparation (n = 125)	t/χ2 value	P value
Anesthesia and surgery	305 (85.0)	98 (78.4)	2.862	0.091
Low-residue diet 1 day prior	286 (79.7)	40 (32.0)	95.805	< 0.001a
High-fiber food intake within 24 hours	86 (24.0)	47 (37.6)	8.662	0.003a
First-time colonoscopy	242 (67.4)	68 (54.4)	6.815	0.009a
Complete intake of sodium potassium magnesium sulfate	336 (93.6)	116 (92.8)	0.095	0.759
Time interval from first dose to first bowel movement (minutes)	59.54 ± 2.98	70.92 ± 7.23	-1.723	0.086
Time interval from last dose to start of examination (hours)	6.53 ± 0.10	8.24 ± 0.26	-6.192	< 0.001a
Total exercise time after medication (minutes)	87.76 ± 3.65	46.04 ± 5.80	5.502	< 0.001a
Total number of bowel movements after medication (times)	10.52 ± 0.19	9.09 ± 0.31	3.799	< 0.001a

^aP < 0.05.

Table 3 Logistic regression analysis of factors influencing inadequate bowel preparation for colonoscopy (n = 484)

Independent variable	β coefficient	SE	Wald χ2	OR	95%CI	P value
History of colorectal surgery	1.762	0.586	9.054	5.814	1.848-18.519	0.003
Low-residue diet 1 day prior	-1.928	0.287	45.215	0.145	0.083-0.255	< 0.001
Time interval from last dose to start of examination (hours)	0.369	0.074	25.189	1.447	1.252-1.669	< 0.001
Total exercise time after medication (minutes)	-0.008	0.003	8.962	0.992	0.986-0.997	0.003
Total number of bowel movements after medication (times)	-0.105	0.04	7.011	0.900	0.832-0.973	0.008

OR: Odds ratio; CI: Confidence interval.