Risk factors associated with inflammatory bowel disease: A multicenter case-control study in Brazil

Table 1 Demographic, socioeconomic and environmental aspects of the groups studied (n = 1.456)

Characteristics		CD (n = 548)		UC (n = 492)		Controls (n = 416)
		n	%	n	%	n	%
State of Brazil	Rio de Janeiro	145	26.5	100	20.3	86	20.7
	São Paulo	102	18.6	78	15.9	44	0.6
	Minas Gerais	98	7.9	57	11.6	38	9.1
	Bahia	59	0.8	69	14.0	76	8.3
	Piauí	82	5.0	92	18.7	92	2.1
	Federal District	62	1.3	96	19.5	80	9.2
Age at enrollment (yr)	< 40	267	8.7	159	32.3	162	8.9
	> 40	281	1.3	333	67.7	254	1.1
Age at Diagnosis (yr)	< 40	462	4.3	299	60.8	Not applicable
	> 0	86	5.7	193	39.2
Sex	Male	227	1.4	168	34.1	208	50.0
	Female	321	8.6	324	65.9	208	50.0
Ethnicity	White	263	8.0	189	38.4	143	34.4
	Non-white	285	2.0	303	61.6	273	65.6
Migration	No	348	3.5	297	60.4	266	63.9
	Yes	200	6.5	195	39.6	150	36.1
Educational level	Elementary school	182	3.2	228	46.3	177	42.5
	High school	264	8.2	202	41.1	183	44.0
	Higher education	102	8.6	62	12.6	56	13.5
Monthly family income (minimum wages)	Up to 3	244	4.5	253	51.4	159	38.2
	3 to 5	135	4.6	113	23.0	102	24.5
	5 or more	121	2.1	89	18.1	94	22.6
	Not stated	48	8.8	37	7.5	61	14.7
Living condition	Inadequate	336	61.3	359	73.0	266	63.9
	Adequate	212	8.7	133	27.0	150	36.1
Cohabitants (n)2	Up to 1	116	1.2	110	22.4	83	20.0
	2 to 3	299	4.6	252	51.2	186	44.7
	4 to 8	133	4.3	130	26.4	147	35.3
Cohabitants (n)1	1 to 3	106	9.3	58	11.8	51	12.3
	4 to 6	220	0.1	172	35.0	161	38.7
	7 or more	222	0.5	262	53.3	204	49.0
Rural living	No	356	5.0	266	54.1	223	3.6
	Yes	192	5.0	226	45.9	193	6.4
Exposure to domestic animal1	No	75	3.7	64	13.0	61	14.7
	Yes	473	86.3	428	87.0	355	85.3
Breastfeeding (for at least 6 mo)	No	42	7.7	21	4.3	23	5.5
	Yes	472	86.1	421	85.6	362	87.0
	Not stated	34	6.2	50	10.2	31	7.5
Consumption of treated water1	No	223	40.7	316	64.2	214	51.4
	Yes	325	59.3	176	35.8	202	48.6
Vaccination	No	62	11.3	71	14.4	26	6.3
	Yes	486	88.7	421	85.6	390	93.8
Infectious diseases1	No	65	11.9	41	8.3	29	7.0
	Yes	483	88.1	451	91.7	387	93.0
Worm disease	No	193	35.2	141	28.7	140	33.7
	Yes	355	64.8	351	71.3	276	66.3
Bowel infection	No	225	41.1	218	44.3	229	55.0
	Yes	323	58.9	274	55.7	187	45.0
Appendectomy	No	496	90.5	484	98.4	393	94.5
	Yes	52	9.5	8	1.6	23	5.5
Exposure to tobacco at diagnosis	Never	353	64.4	273	55.5	280	67.3
	Former	145	26.5	191	38.8	91	21.9
	Current	50	9.1	28	5.7	45	0.8
Familial IBD	No	438	79.9	430	87.4	393	94.5
	Yes	80	14.6	46	9.3	14	3.4
	Not stated	30	5.5	16	3.3	09	2.2

¹Childhood.

²Adulthood. IBD: Inflammatory bowel disease; CD: Crohn’s disease; UC: Ulcerative colitis.

Table 2 Significant variables obtained from the comparative univariate and multiple multinomial logistic analysis between Crohn’s disease and ulcerative colitis, with healthy control as reference

Characteristics		Univariate multinomial logistic model1				Multiple multinomial logistic model1
		CD		UC		CD		UC
		OR	P value	OR	P value	OR	P value	OR	P value
State of Brazil	Rio de Janeiro	2.18	< 0.001	0.97	0.881	1.84	0022	0.84	0.486
	São Paulo	2.99	< 0.001	1.48	0.107	2.41	0.002	1.27	0.399
	Min Minas Gerais	3.33	< 0.001	1.25	0.388	2.61	0.001	1.28	0.400
	Bahia	1.00	0.994	0.76	0.215	0.98	0.941	0.69	0.156
	Piauí	1.15	0.539	0.83	0.388	0.92	0.736	0.81	0.376
	Federal District	1		1		1		1
Age at enrollment (yr)	< 40	1.49	0.003	0.75	0.038	1.75	0.001	1.14	0.462
	> 40	1		1		1		1
Sex	Male	0.71	0.008	0.52	< 0.001	0.75	0.052	0.59	< 0.001
	Female	1		1		1		1
Ethnicity	White	1.76	< 0.001	1.19	0.208	1.21	0.227	1.08	0.620
	Non-white	1		1		1		1
Educational level	Elementary school	0.57	0.004	1.16	0.471	0.48	0.004	0.68	0.147
	High school	0.79	0.225	1.00	0.989	0.74	0.187	0.83	0.448
	Higher education	1		1		1		1
Monthly family income (minimum wages)	Up to 3	1.19	0.304	1.68	0.004	1.79	0.007	1.61	0.032
	3 to 5	1.03	0.884	1.17	0.435	1.25	0.311	1.13	0.587
	5 or more	1		1		1		1
	Not stated	0.61	0.038	0.64	0.081	0.94	0.826	0.77	0.350
Living condition	Inadequate	0.89	0.404	1.52	0.004	1.17	0.411	1.47	0.046
	Adequate	1		1		1		1
Cohabitants (n)3	Up to 1	1.55	0.020	1.50	0.032	1.07	0.764	1.20	0.400
	2 to 3	1.78	< 0.001	1.53	0.006	1.67	0.002	1.57	0.007
	4 to 8	1		1		1		1
Cohabitants (n)2	1 a 3	1.91	0.001	0.89	0.569	1.17	0.518	0.99	0.954
	4 a 6	1.26	0.109	0.83	0.201	1.02	0.887	0.90	0.514
	7 or more	1		1		1		1
Rural living	No	1.61	< 0.001	1.02	0.890	1.37	0.080	1.66	0.004
	Yes	1		1		1		1
Consumption of treated water2	No	0.65	0.001	1.70	< 0.001	0.71	0.037	1.52	0.012
	Yes	1		1		1		1
Vaccination	No	1.91	0.008	2.53	< 0.001	3.08	< 0.001	2.46	0.001
	Yes	1		1		1		1
Infectious disease2	No	1.80	0.012	1.21	0.444	1.99	0.007	1.44	0.178
	Yes	1		1		1		1
Bowel infection	No	0.57	< 0.001	0.65	0.001	0.56	< 0.001	0.68	0.009
	Yes	1		1		1		1
Appendectomy	No	0.56	0.025	3.54	0.002	0.63	0.103	4.89	< 0.001
	Yes	1		1		1		1
Exposure to tobacco	Never	1.14	0.567	1.57	0.079	1.05	0.840	1.52	0.132
	Former	1.43	0.141	3.37	< 0.001	1.75	0.039	3.40	< 0.001
	Current	1		1		1		1
Familial IBD	No	0.20	< 0.001	0.33	< 0.001	0.19	< 0.001	0.30	< 0.001
	Yes	1		1		1		1
	Not stated	0.58	0.259	0.54	0.234	0.55	0.248	0.41	0.106

¹Category of reference = healthy control.

²Childhood.

³Adulthood. IBD: Inflammatory bowel disease; CD: Crohn’s disease; UC: Ulcerative colitis; OR: Odd ratios.

Table 3 Non-significant variables obtained from the comparative univariate and multiple multinomial logistic analysis between Crohn’s disease and ulcerative colitis, with healthy control as reference

Characteristics		Univariate multinomial logistic model1				Multiple multinomial logistic model1
		CD		UC		CD		UC
		OR	P value	OR	P value	OR	P value	OR	P value
Migration	No	0.98	0.888	0.86	0.269	0.83	0.258	1.04	0.802
	Yes	1		1		1		1
Exposure to domestic animal2	No	0.92	0.666	0.87	0.471	0.88	0.542	0.94	0.786
	Yes	1		1		1		1
Breastfeeding	No	1.40	0.210	0.79	0.435	1.14	0.661	0.60	0.116
	Yes	1		1		1		1
	Not stated	0.84	0.503	1.39	0.172	0.96	0.897	1.22	0.456
History of worm disease	No	1.07	0.613	0.79	0.105	0.99	0.946	0.81	0.187
	Yes	1		1		1		1

¹Category of reference = healthy control.

²Childhood. CD: Crohn’s disease; UC: Ulcerative colitis; OR: Odd ratios.

Table 4 Comparative final multiple multinomial logistic model between the Crohn’s disease and ulcerative colitis groups

Characteristics		Final multiple multinomial logistic model1
		CD		UC
		OR	95%CI	OR	95%CI
State of Brazil	Rio de Janeiro	1.86	1.11-3.07	0.85	0.52-1.37
	São Paulo	2.52	1.48-4.28	1.27	0.75-2.14
	Minas Gerais	2.68	1.56-4.58	1.30	0.75-2.25
	Bahia	0.86	0.51-1.45	0.71	0.43-1.16
	Piauí	0.88	0.54-1.43	0.84	0.53-1.31
	Federal District	1		1
Age at enrollment (yr)	18 - 39	1.73	1.25-2.39	1.09	0.78-1.52
	40 - 80	1		1
Sex	Male	0.76	0.56-1.00	0.59	0.44-0.78
	Female	1		1
Educational level	Elementary school	0.45	0.27-0.73	0.67	0.39-1.12
	High school	0.70	0.45-1.09	0.84	0.52-1.33
	Higher education	1		1
Monthly family income (minimum wages)	Up to 3	1.78	0.54-1.55	1.57	0.45-1.35
	3 to 5	1.21	1.16-2.70	1.14	1.02-2.40
	5 or more	1		1
	Not stated	0.92	0.78-1.86	0.78	0.72-1.77
Living condition	Inadequate	1.15	0.79-1.66	1.48	1.01-2.16
	Adequate	1		1
Cohabitants (n)3	Up to 1	1.09	0.72-1.65	1.24	0.82-1.87
	2 to 3	1.70	1.22-2.35	1.60	1.15-2.21
	4 to 8	1		1
Rural living	No	1.33	0.95-1.86	1.62	1.16-2.25
	Yes	1		1
Consumption of treated water	No	0.72	0.51-0.98	1.53	1.11-2.11
	Yes	1		1
Vaccination	No	3.11	1.82-5.29	2.51	1.49-4.21
	Yes	1		1
Infectious disease2	No	1.99	1.20-3.26	1.37	0.80-2.32
	Yes	1		1
Bowel infection	No	0.56	0.42-0.73	0.67	0.50-0.89
	Yes	1		1
Appendectomy	No	0.63	0.36-1.09	4.79	2.05-11.11
	Yes	1		1
Exposure to tobacco	Never	1.08	0.66-1.76	1.50	0.87-2.57
	Former	1.81	1.06-3.05	3.36	1.91-5.90
	Current	1		1
Familial IBD	No	0.19	0.20 -1.51	0.30	0.14-1.23
	Yes	1		1
	Not stated	0.56	0.10-0.34	0.42	0.16-0.56

¹After excluding the variables that were not statistically significant (P > 0.05) in the multiple model (category of reference = healthy controls).

²Childhood.

³Adulthood. CD: Crohn’s disease; UC: Ulcerative colitis; OR: Odd ratios.