Crohn’s disease environmental factors in the developing world: A case-control study in a statewide catchment area in Brazil

Table 1 Demographics and environmental factors from Crohn’s disease and control groups (n = 308) n (%)

	Groups CD1 (n = 145)	Controls (n = 163)	P value1
Sex
Male	62 (42.8)	43 (26.4)	0.002
Female	83 (57.2)	120 (73.6)
Age (yr)
18-39	79 (54.5)	50 (30.7)	< 0.0001
40-80	66 (45.5)	113 (69.3)
Race
White	74 (51)	65 (39.9)	0.050
Non-white	71 (49)	98 (60.1)
Educational level
Elementary	45 (31)	79 (48.5)
High school	79 (54.5)	70 (42.9)	0.006
Graduate school	21 (14.5)	14 (8.6)
Family income2
< 3	46 (31.7)	54 (33.1)
3-5	44 (30.3)	55 (33.7)	0.730
> 5	40 (27.6)	36 (22.1)
No information	15 (10.3)	18 (11)
Rural area
No	114 (78.6)	106 (65)	0.008
Yes	31 (21.4)	57 (35)
Housing conditions
Inadequate	12 (8.3)	12 (7.4)	0.765
Adequate	133 (91.7)	151 (92.6)
Family size in adulthood (n)
Until 1	23 (15.9)	47 (28.8)
2-3	85 (58.6)	83 (50.9)	0.024
4-8	37 (25.5)	33 (20.2)
Family size in childhood (n)
1-3	45 (31)	35 (21.5)
4-6	61 (42.1)	56 (34.4)	0.006
> 7	39 (26.9)	72 (44.2)
Pets
No	30 (20.7)	21 (12.9)	0.066
Yes	115 (79.3)	142 (87.1)
Breastfeeding
No	12 (8.3)	13 (8)
Yes	125 (86.2)	133 (81.6)	0.289
Unknown	8 (5.5)	17 (10.4)
Exposure to untreated water
No	43 (29.7)	71 (43.6)	0.012
Yes	102 (70.3)	92 (56.4)
Vaccine (childhood)
No	12 (8.3)	20 (12.3)	0.252
Yes	133 (91.7)	143 (87.7)
Viral diseases (childhood)
No	17 (11.7)	11 (6.7)	0.129
Yes	128 (88.3)	152 (93.3)
Helmintic infections
No	45 (31)	45 (27.6)	0.509
Yes	100(69)	118 (72.4)
Exposure to enteric pathogens
No	67 (46.2)	106 (65)	0.001
Yes	78 (53.8)	57 (35)
Previous appendectomy
No	133 (91.7)	153 (93.9)	0.466
Yes	12 (8.3)	10 (6.1)
Tobacco exposure
Never	86 (59.3)	106 (65)
Prior	42 (29)	33 (20.2)	0.190
Current	17 (11.7)	24 (14.7)
Family history
No	132 (91)	153 (93.9)	0.346
Yes	13 (9)	10 (6.1)

¹χ² test;

²Minimum wage. CD: Crohn’s disease.

Table 2 Univariate analysis of associations between demographics, environmental factors in Crohn’s disease patients

Characteristics	Logistic univariate models
	OR	95%CI	P value2
Sex
Male	2.09	1.29-3.37	0.003
Female	1.00
Age (yr)
18-39	2.71	1.70-4.31	< 0.001
40-80	1.00
Race
White	1.57	1.00-2.47	0.050
Non-white	1.00
Educational level
Elementary	1.00
High school	1.98	1.22-3.22	0.006
Graduate school	2.63	1.21-5.68	0.014
Family income1
< 3	1.00
3-5	0.94	0.54-1.64	0.826
> 5	1.30	0.72-2.37	0.384
No information	0.98	0.44-2.15	0.957
Rural area
No	1.98	1.19-3.29	0.009
Yes	1.00
Housing conditions
Inadequate	1.14	0.49-2.61	0.765
Adequate	1.00
Family size in adulthood (n)
Until 1	1.00
2-3	2.09	1.17-3.75	0.013
4-8	2.29	1.15-4.54	0.018
Family size in childhood (n)
1-3	2.37	1.31-4.27	0.004
4-6	2.01	1.18-3.42	0.010
> 7	1.00
Pets
No	1.76	0.96-3.24	0.068
Yes	1.00
Breastfeeding
No	1.00
Yes	1.02	0.45-2.31	0.966
Unknown	0.51	0.16-1.61	0.251
Exposure to untreated water
No	1.00
Yes	1.83	1.14-2.93	0.012
Vaccine (childhood)
No	1.00
Yes	1.55	0.73-3.29	0.254
Viral diseases (childhood)
No	1.84	0.83-4.06	0.134
Yes	1.00
Helmintic infections
No	1.18	0.72-1.93	0.509
Yes	1.00
Exposure to enteric pathogens
No	1.00
Yes	2.16	1.37-3.42	0.001
Previous appendectomy
No	1.00
Yes	1.38	0.57-3.29	0.468
Tobacco exposure
Never	1.00
Prior	1.57	0.92-2.60	0.101
Current	0.87	0.44-1.73	0.697
Family history
No	1.00
Yes	1.51	0.64-3.54	0.348

¹Minimum wage,

²χ² test. CD: Crohn’s disease.

Table 3 Multiple linear regression to assess independent factors associated with the development of Crohn’s disease

Characteristics	Multivariate analysis 1			Multivariate analysis 2
	1ORaj	95%CI	P value	1ORaj	95%CI	P value
Sex
Male	2.08	1.18-3.68	0.011	2.09	1.22-3.59	0.007
Female	1.00			1.00
Age (yr)
18-39	2.83	1.51-5.32	0.001	3.10	1.71-5.63	< 0.001
40-80	1.00			1.00
Race
White	2.30	1.31-4.02	0.004	2.32	1.36-3.97	0.002
Non-white	1.00			1.00
Educational level
Elementary	1.00
High school	1.44	0.75-2.75	0.266
Graduate school	1.45	0.52-4.04	0.470
Family income1
< 3	1.00
3-5	0.83	0.42-1.64	0.609
> 5	0.90	0.40-2.00	0.807
No information	1.74	0.67-4.51	0.254
Rural area
No	1.32	0.65-2.68	0.432
Yes	1.00
Housing conditions
Inadequate	1.36	0.49-3.79	0.548
Adequate	1.00
Family size in adulthood (n)
Until 1	1.00			1.00
2-3	3.26	1.59-6.68	0.001	3.02	1.52-5.99	0.002
4-8	3.16	1.36-7.34	0.007	2.87	1.26-6.50	0.012
Family size in childhood (n)
1-3	1.28	0.57-2.84	0.541	1.66	0.81-3.40	0.159
4-6	2.08	1.06-4.08	0.032	2.34	1.27-4.32	0.006
> 7	1.00			1.00
Pets
No	1.45	0.69-3.05	0.323
Yes	1.00
Breastfeeding
No	1.00
Yes	0.77	0.28-2.09	0.616
Unknown	0.48	0.12-1.89	0.296
Exposure to untreated water
No	1.00
Yes	1.54	0.80-2.93	0.188
Vaccine (childhood)
No	1.00
Yes	0.57	0.20-1.58	0.284
Viral diseases (childhood)
No	2.42	0.90-6.48	0.078	2.23	0.88-5.62	0.088
Yes	1.00			1.00
Helmintic infections
No	0.91	0.51-1.65	0.776
Yes	1.00
Exposure to enteric pathogens
No	1.00			1.00
Yes	2.89	1.62-5.17	< 0.001	2.23	1.41-4.10	0.001
Previous appendectomy
No	1.00			1.00
Yes	2.71	0.93-7.83	0.065	2.47	0.89-6.83	0.080
Tobacco exposure
Never	1.00			1.00
Prior	3.13	1.57-6.26	0.001	2.83	1.46-5.47	0.002
Current	1.13	0.50-2.54	0.768	1.12	0.51-2.44	0.775
Family history
No	1.00
Yes	1.27	0.45-3.53	0.644

¹OR_aj = Odd Ratio adjusted. In the final model only the variables included were statistically significant (95%CI not including value 1). P value Hosmer-Lemeshow statistic for setting the final model = 0.406.