Table 3. Association of melanosis coli with number of colorectal polyps of various sizes^a.

Groups	Numbers of colorectal polyp in different sizes (mean ± SD)
	Total number	Diameter ≤ 5 mm	Diameter 6–9 mm	Diameter ≥10 mm	Diameter ≥20 mm
Melanosis coli (n = 203)	1.05 ± 2.05	0.74 ± 1.66	0.27 ± 1.04	0.02 ± 0.15	0.03 ± 0.16
Control (n = 436)	0.54 ± 0.96	0.35 ± 0.84	0.13 ± 0.36	0.04 ± 0.20	0.02 ± 0.16
p value	0.001*	0.002*	0.06	0.38	0.60
Degrees of melanosis coli:
Grade I (n = 128)	0.98 ±1.90	0.73 ± 1.78	0.22 ± 0.72	0.03 ± 0.17	0.02 ± 0.15
Grade II (n = 52)	1.04 ± 2.05	0.73 ± 1.39	0.23 ± 1.02	0.02 ± 0.14	0.05 ± 0.23
Grade III (n = 23)	1.46 ± 2.78	0.79 ± 1.59	0.63 ± 2.06	0	0
p value	0.58	0.98	0.14	0.63	0.30
Distribution of melanosis coli:
Right colon (n = 53)	1.13 ±2.65	0.83± 2.29	0.25 ± 1.02	0.02 ± 0.13	0.02 ± 0.13
Left colon (n = 35)	1.14 ± 1.80	0.69 ± 1.53	0.14 ± 0.42	0.03 ± 0.16	0.08 ± 0.27
Total colon (n = 115)	0.98 ± 1.82	0.71 ± 1.34	0.32 ± 1.17	0.02 ± 0.15	0.02 ± 0.13
p value	0.87	0.89	0.98	0.25	0.10

a: Patients with numerous polyps (≥20) were excluded in this comparison.

*p<0.05