Potential risk factors for celiac disease in childhood: a case-control epidemiological survey

Figures & data

Figure 1 Flow chart for participant inclusion.

Abbreviations: NCGS, non-celiac gluten sensitivity; US, United States.

Table 1 Demographics

Variable	Cases	Controls
n	332	241
Age of child, mean (SD)	8.5 (2.6)	6.1 (2.8)
Age of diagnosis, mean (SD)	6.1 (2.4)	–
Sex of child, male, n (%)	130 (39.2)	107 (44.4)
Maternal age at birth of child, mean (SD)	30.8 (4.5)	31.5 (4.9)
Ethnicity of child, n (%)
White (non-Hispanic)	299 (90.1)	205 (85.1)
African American/Black	1 (0.3)	–
Asian	–	3 (1.2)
Hawaiian/Pacific Islander	–	1 (0.4)
Hispanic/Latino	7 (2.1)	7 (2.9)
Native American	3 (0.9)	–
Multiethnic	13 (3.9)	17 (7.1)
Other	9 (2.7)	8 (3.3)
Regions of the US, n (%)
Midwest	92 (27.7)	65 (27)
Northeast	93 (28)	59 (24.5)
Southeast	55 (16.6)	47 (19.5)
Southwest	25 (7.5)	23 (9.5)
West	67 (20.2)	47 (19.5)
Maternal education, n (%)
Grade school or some high school	1 (0.3)	1 (0.4)
High school	22 (6.6)	14 (5.8)
Some college	44 (13.3)	46 (19.1)
Bachelor’s or associate’s degree	154 (46.4)	111 (46.1)
Graduate or professional degree	111 (33.4)	69 (28.6)
Relationship to the child, n (%)
Biological mother	326 (98.2)	238 (98.8)
Biological father	6 (1.8)	3 (1.2)
Other conditions in child, n (%)
None	199 (59.9)	174 (72.2)
Attention deficit/hyperactivity disorder	45 (13.6)	25 (10.4)
Autism spectrum disorder	8 (2.4)	12 (5)
Down syndrome	2 (0.6)	1 (0.4)
Lactose intolerance	41 (12.3)	18 (7.5)
Peanut allergy	13 (3.9)	9 (3.7)
Other food allergy	26 (7.8)	18 (7.5)
Other	68 (20.5)	25 (10.4)
How did (respondent) hear about survey? n (%)
Beyond Celiac	61 (18.4)	3 (2.0)
National Celiac Association or Chapter	11 (3.3)	1 (0.4)
Other CD or gluten related group	184 (55.4)	32 (13.3)
General interest parents group	41 (12.3)	49 (20.3)
Advertisement	2 (0.6)	44 (18.3)
Friend	21 (6.3)	102 (42.3)
Other	12 (3.6)	10 (4.1)
Respondent provided an email address, n (%)	314 (94.6)	209 (86.7)

Abbreviations: CD, celiac disease; SD, standard deviation; %, percentage of cases or controls.

Table 2 Categorical variables and ORs

Question^a/variable	Cases	Controls
	n (%)	n (%)	OR	95% CI	P-value
Ear infections up to second birthday?
None	101 (30.4)	95 (39.4)	0.690	0.485–0.983	0.039*
1	55 (16.6)	55 (22.8)	0.689	0.453–1.048	0.080
2–3	71 (21.4)	47 (19.5)	1.160	0.765–1.757	0.484
>4 or persistent	85 (25.6)	35 (14.5)	2.108	1.361–3.264	0.001*
I’m not sure	20 (6)	9 (3.7)	–	–	–
Courses of antibiotics up to second birthday?
None	51 (15.4)	56 (23.2)	0.665	0.434–1.019	0.060
1	50 (15.1)	55 (22.8)	0.665	0.432–1.021	0.061
2–3	79 (23.8)	71 (29.5)	0.769	0.527–1.122	0.173
4–7	68 (20.5)	34 (14.1)	1.623	1.032–2.551	0.035*
8+	40 (12)	13 (5.4)	2.478	1.293–4.748	0.004*
I’m not sure	44 (13.3)	12 (5)	–	–	-
Duration of breastfeeding?
Never breastfed	63 (19)	40 (16.6)	1.177	0.761–1.821	0.464
3 months or less	53 (16)	43 (17.8)	0.875	0.562–1.360	0.552
>3 months and up to 6 months	43 (13)	26 (10.8)	1.230	0.733–2.065	0.432
>6 months and up to 12 months	76 (22.9)	44 (18.3)	1.329	0.876–2.013	0.178
>12 months	97 (29.2)	88 (36.5)	0.718	0.504–1.022	0.651
Duration of vitamin D drops as a baby?
No vitamin D drops	199 (59.9)	159 (66)	0.811	0.563–1.170	0.262
3 months or less	38 (11.4)	33 (13.7)	0.839	0.508–1.385	0.492
>3 months and up to 6 months	31 (9.3)	12 (5)	2.031	1.019–4.048	0.041*
>6 months and up to 12 months	31 (9.3)	17 (7.1)	1.401	0.755–2.600	0.283
>12 months	8 (2.4)	8 (3.3)	0.739	0.273–2.000	0.550
I’m not sure	25 (7.5)	12 (5)	–	–	–
Supplemental vitamin D between 2-3?
No	225 (67.8)	164 (68)	1.190	0.818–1.731	0.362
Occasionally or only part of year	44 (13.3)	33 (13.7)	1.025	0.630–1.669	0.920
Regularly or fairly regularly for entire year	39 (11.7)	39 (16.2)	0.732	0.453–1.184	0.203
I’m not sure	24 (7.2)	5 (2.1)	–	–	–
Age at which gluten introduced?
3 months or younger	9 (2.7)	6 (2.5)	1.094	0.384–3.117	0.866
>3 months and up to 6 months	119 (35.8)	76 (31.5)	1.220	0.856–1.737	0.271
>6 months and up to 12 months	172 (51.8)	138 (57.3)	0.804	0.574–1.126	0.204
>12 months	27 (8.1)	18 (7.5)	1.100	0.590–2.047	0.764
I’m not sure	5 (1.5)	3 (1.2)	–	–	–
Type of liquid cow’s milk between 2-3?
No cow’s milk at this time	29 (8.7)	31 (12.9)	0.653	0.382–1.116	0.117
Skim milk	26 (7.8)	6 (2.5)	3.354	1.348–8.284	0.006*
Low fat milk	23 (6.9)	17 (7.1)	0.988	0.516–1.893	0.971
2% milk	98 (29.5)	69 (28.6)	1.055	0.731–1.521	0.777
Whole milk	151 (45.5)	116 (48.1)	0.910	0.651–1.271	0.579
I’m not sure	5 (1.5)	2 (0.8)	–	–	–
Daily quantity of milk between 2-3?
No cow’s milk at this time	29 (8.7)	31 (12.9)	0.683	0.399–1.170	0.163
1/2 cup or less	39 (11.7)	27 (11.2)	1.116	0.661–1.882	0.682
>1/2 cup and up to 1 cup	46 (13.9)	32 (13.3)	1.112	0.684–1.811	0.668
>1 cup and up to 2 cups	93 (28)	63 (26.1)	1.180	0.808–1.721	0.391
>2 cups and up to 3 cups	72 (21.7)	57 (23.7)	0.951	0.639–1.417	0.806
>3 cups	28 (8.4)	24 (10)	0.878	0.495–1.559	0.657
I’m not sure	25 (7.5)	7 (2.9)	–	–	–
Water type at age 2?
Distilled or RO bottled water	8 (2.4)	8 (3.3)	0.733	0.271–1.981	0.538
Any other type of bottled water	32 (9.6)	24 (10)	0.984	0.564–1.719	0.955
Distilled or RO water from home unit	11 (3.3)	11 (4.6)	0.730	0.311–1.713	0.468
Softened water from home unit	6 (1.8)	4 (1.7)	1.111	0.310–3.981	0.872
Filtered water from home unit	132 (39.8)	91 (37.8)	1.222	0.797–1.578	0.510
Plain tap water (unfiltered)	113 (34)	80 (33.2)	1.068	0.751–1.518	0.715
Well water	18 (5.4)	17 (7.1)	0.770	0.388–1.527	0.454
Other	6 (1.8)	6 (2.5)	0.734	0.234–2.301	0.595
I’m not sure	6 (1.8)	–	–	–	–

Notes: ^aQuestions and answers in this table were edited for brevity; *P-values<0.05.

Abbreviations: OR, Wald odds ratio; RO, reverse osmosis; 95% CI, 95% Wald confidence interval.

Table 3 ORs and aORs

	Unadjusted			Adjusted^a
Variable	OR	95% CI	P-value	aOR	95% CI	P-value
Ear infection (#)	1.239	1.103–1.394	<0.001*	1.183	1.041–1.348	0.010*
Antibiotic (courses)	1.192	1.099–1.298	<0.001*	1.133	1.037–1.244	0.007*
Breastfeeding (months)	0.986	0.963–1.010	0.250	0.995	0.969–1.021	0.681
Vit D drops >3 months (binary)	1.533	0.991–2.402	0.058	1.749	1.079–2.872	0.025*
Vit D supplement (trinary)	0.870	0.690–1.098	0.240	0.915	0.707–1.185	0.499
Age gluten (months)	0.983	0.940–1.027	0.441	0.992	0.944–1.042	0.750
Skim milk (binary)	3.354	1.449–9.128	0.009*	3.556	1.430–10.22	0.010*
Milk quantity (cups/day)	1.009	0.877–1.162	0.897	0.941	0.805–1.100	0.448
RO water (binary)	0.723	0.372–1.404	0.335	0.656	0.312–1.370	0.261

Notes: ^aCovariates for the adjusted odds ratios are: age of the child, ethnicity of child, maternal education, and maternal age at birth of the child; *P-values<0.05.

Abbreviations: aOR, adjusted odds ratio; OR, odds ratio; RO, reverse osmosis; Vit, vitamin; 95% CI, 95% confidence interval.