Protective effect of appendectomy against the onset of ulcerative colitis: A case-control study

Table 1 General clinical data of patients, n (%)/mean ± SD

	UC (n = 313)	Non-UC (n = 313)	t/χ2	P value
Age	42.50 ± 13.94	41.84 ± 13.71	0.590	0.556
Sex			0.058	0.810
Male	176 (56.23)	173 (55.27)
Female	137 (43.77)	140 (44.73)
Nationality			29.344	< 0.001
Han	159 (50.8)	225 (71.88)
Ethnic minorities	154 (49.2)	88 (28.12)
Education level			2.334	0.127
Low and middle education	183 (58.47)	164 (52.40)
Higher education	130 (41.53)	149 (47.60)
Region of residence			8.395	0.004
Urban	214 (68.37)	246 (78.59)
Rural	99 (31.63)	67 (21.41)
Smoking history			6.157	0.013
Smoking	58 (18.53)	84 (26.84)
No smoking	255 (81.47)	229 (73.16)
Drinking history			10.102	0.001
Drinking	43 (13.74)	74 (23.64)
No drinking	270 (86.26)	239 (76.36)
History of appendectomy			37.541	< 0.001
Appendectomized	43 (13.74)	3 (0.96)
Nonappendectomized	270 (86.26)	310 (99.04)

UC: Ulcerative colitis.

Table 2 Comparison of blood routine results between ulcerative colitis and non-ulcerative colitis, median (25^th-75^th percentiles)

	UC (n = 313)	Non-UC (n = 313)	Z	P value
WBC (× 109/L)	6.96 (5.41-9.08)	5.81 (4.91-7.19)	-5.980	< 0.001
Neutrophile granulocyte (× 109/L)	4.15 (3.04-5.97)	3.16 (2.51-4.12)	-7.319	< 0.001
Lymphocyte (× 109/L)	1.77 (1.37-5.97)	2.01 (1.66-2.45)	4.778	< 0.001
Monocytes (× 109/L)	0.52 (0.38-0.69)	0.40 (0.32-0.52)	-7.385	< 0.001
RBC (× 1012/L)	4.42 (3.93-4.80)	4.53 (4.16-4.95)	3.449	< 0.001
Hb (g/L)	128.00 (108.75-143.00)	138.00 (125.00-152.00)	6.348	< 0.001
PLT (× 109/L)	277.50 (211.75-350.25)	230.00 (193.00-264.00)	-6.733	< 0.001
NLR	2.38 (1.62-3.68)	1.55 (1.20-2.07)	-9.520	< 0.001
PLR	154.00 (120.64-219.67)	111.91 (91.11-143.25)	-9.251	< 0.001

UC: Ulcerative colitis; WBC: White blood cell; RBC: Red blood cell; Hb: Hemoglobin; PLT: Platelet; NLR: Neutrophil-to-lymphocyte; ratio; PLR: Platelet-to-lymphocyte ratio.

Table 3 Blood routine factors influencing incipient ulcerative colitis

	β	SE	Wald	P value	OR	95%CI
						Lower limit	Upper limit
WBC	0.121	0.104	1.361	0.243	1.129	0.921	1.383
Neutrophile Granulocyte	-0.043	0.112	0.148	0.701	0.958	0.769	1.193
Lymphocyte	-0.452	0.317	2.026	0.155	0.637	0.342	1.186
Monocytes	2.775	0.670	17.146	0.000	16.039	4.312	59.653
RBC	0.296	0.252	1.384	0.239	1.345	0.821	2.204
Hb	-0.026	0.007	12.238	0.001	0.975	0.961	0.989
PLT	0.001	0.002	0.056	0.812	1.001	0.996	1.005
NLR	0.260	0.238	1.196	0.274	1.297	0.814	2.066
PLR	0.003	0.003	0.764	0.382	1.003	0.996	1.010
Constant	-0.154	0.879	0.031	0.861	0.858

WBC: White blood cell; RBC: Red blood cell; Hb: Hemoglobin; PLT: Platelet; NLR: Neutrophil-to-lymphocyte; ratio; PLR: Platelet-to-lymphocyte ratio.

Table 4 Comparison of onset age, scope of lesions, and degree of disease activity between male and female with ulcerative colitis, n (%)/mean ± SD

	Male (n = 176)	Female (n = 137)	t/χ2	P value
Onset age	42.46 ± 13.75	42.54 ± 14.24	-0.50	0.96
Scope of lesions			4.90	0.09
E1	17 (9.66)	25 (18.25)
E2	66 (37.50)	46 (33.57)
E3	93 (52.84)	66 (48.18)
Degree of disease activity			2.29	0.52
Clinical remission	6 (3.41)	2 (1.46)
Mild	29 (16.48)	29 (21.17)
Moderate	112 (63.64)	82 (59.85)
Severe	29 (16.48)	24 (17.52)

Table 5 Comparison of onset age of different sexes between appendectomized group and nonappendectomized group, mean ± SD

	Appendectomized	Non-appendectomized	t value	P value
Onset age	49.51 ± 14.16	41.38 ± 13.61	-3.621	<0.001
Onset age of male	50.52 ± 13.95	41.37 ± 13.40	-2.903	0.004
Onset age of female	48.55 ± 14.62	41.39 ± 13.94	-2.188	0.029

Table 6 Age comparison of confirmed ulcerative colitis between two groups, n (%)

Onset age	Appendectomized	Non-appendectomized	χ2	P value
10-19	0 (0.00)	15 (5.56)	2.509	0.113
20-29	3 (6.98)	49 (18.15)	3.342	0.068
30-39	7 (16.28)	54 (20.00)	0.327	0.567
40-49	12 (27.91)	82 (30.37)	0.107	0.743
50-59	13 (30.23)	44 (16.30)	4.837	0.028
≥ 60	8 (18.60)	26 (9.63)	3.086	0.079

Table 7 Comparison of clinical data between two groups, n (%)/mean ± SD

	Appendectomized (n = 43)	Non-appendectomized (n = 270)	t/χ2	P value
Age	49.51 ± 14.16	41.38 ± 13.61	-3.621	< 0.001
Sex			1.107	0.293
Male	21 (48.84)	155 (57.41)
Female	22 (51.16)	115 (42.59)
Nationality			7.716	0.007
Han	30 (69.77)	129 (47.78)
Ethnic minorities	13 (30.23)	141 (52.22)
Region of residence			7.202	0.007
Urban	37 (86.05)	177 (65.56)
Rural	6 (13.95)	93 (34.44)
Education level			0.509	0.476
Low and middle education	23 (53.49)	160 (59.26%)
Higher education	20 (46.51)	110 (40.74%)
Smoking history			0.167	0.682
Smoking	7 (16.28)	51 (18.89)
No smoking	36 (83.72)	219 (81.11)
Drinking history			1.923	0.166
Drinking	3 (6.98)	40 (14.81)
No drinking	40 (93.02)	230 (85.19)
Degree of disease activity			48.739	< 0.001
Clinical remission	4 (9.3)	4 (1.48)	9.109	0.003
Mild	22 (51.16)	36 (13.33)	35.162	< 0.001
Moderate	16 (37.21)	178 (65.93)	12.981	< 0.001
Severe	1 (2.33)	52 (19.26)	7.562	0.006
Scope of lesions			21.631	< 0.001
E1	13 (30.23)	29 (10.74)	12.130	< 0.001
E2	21 (48.84)	91 (33.70)	3.697	0.055
E3	9 (20.93)	150 (55.56)	17.793	< 0.001