Table 1.

Demographic characteristics of IBD cases and controls at the index date from 1980 to 2010

Characteristic	IBD [n = 736]	Controls [n = 1472]	p-value
Median age at index date, years [range]	34 [1.2–93]	34 [1.2–93]	1.00
< 18 years, n [%]	87 [11.8%]	174 [11.8%]
18–60 years, n [%]	559 [76.0%]	1118 [76.0%]
> 60 years, n [%]	90 [12.2%]	180 [12.2%]
Male, n [%]	405 [55%]	810 [55%]	1.00
Race, n [%]
White	665 [90%]	1074 [73%]	<0.001
African American	12 [1.7%]	81 [5.5%]
Asian	10 [1.4%]	52 [3.5%]
Other	6 [0.8%]	31 [2%]
Unknown	43 [6.1%]	234 [16%]
Ethnicity, n [%]
Hispanic	6 [1%]	45 [3%]	<0.001
Non-Hispanic	626 [85%]	996 [68%]
Unknown	104 [14%]	431 [29%]
Median duration before index date, years [range]	5 [0.5–5]	5 [0.4–5]	<0.001
Median duration of follow-up after index date, years [range]	14.8 [0.1–36.2]	10.0 [0.1–36.5]	<0.001
Obesity [BMI ≥ 30 kg/m2], n [%]	221/730 [30.0%]	371/1467 [25.2%]	0.08
1st degree family history of IBD, n [%]	42 [5.7%]	3 [0.2%]	<0.001
Smoking, n [%]
Current smoking	123 [16.7%]	229 [15.6%]	0.48
Former smoking	150 [20.4%]	152 [10.3%]	<0.001
Any antibiotic use, n [%]	455 [61.8%]	495 [33.6%]	<0.001
1–3 courses of antibiotics	357 [48.5%]	436 [29.6%]
4–6 courses of antibiotics	77 [10.5%]	53 [3.6%]
≥ 7 courses of antibiotics	21 [2.8%]	6 [0.4%]
Daily aspirin use, n [%]	33 [4.5%]	59 [4.0%]	0.60
Statin use, n [%]	20 [2.7%]	63 [4.3%]	0.08

IBD, inflammatory bowel disease; BMI, body mass index.