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Table 1 Distribution of demographic and risk factor characteristics for all participants in analytic sample by smoking status

From: A case-only study of gene-environment interaction between genetic susceptibility variants in NOD2 and cigarette smoking in Crohn's disease aetiology

  Ever Smokers Never Smokers   Smokers at Diagnosis Non-Smokers at Diagnosis   Total Sample
Characteristic n % n % p-value n % n % p-value n %
Total Participants n = 1636 945 57.8% 691 42.2%   522 40.7% 761 59.3%   1636 100.0%
Sex      0.09      0.02   
   Men 281 29.7% 233 33.7%   144 27.6% 258 33.9%   514 31.4%
   Women 664 70.3% 458 66.3%   378 72.4% 503 66.1%   1122 68.6%
Age at Inclusion--Mean
(Standard Deviation)
40.8 ± 10.9 36.3 ± 12.9 2 × 10 -13 41.1 ± 10.6 38.8 ± 13.5 6 × 10 -4 38.9 ± 12.0
Age at Diagnosis--Mean
(Standard Deviation)
27.4 ± 10.1 24.1 ± 10.1 7 × 10 -11 27.3 ± 9.5 26.0 ± 11.4 0.03 26 ± 10.3
Family History      0.17      0.43   
   Yes 229 24.2% 196 28.4%   75 14.4% 128 16.8%   425 26.0%
   No 463 49.0% 320 46.3%   295 56.5% 408 53.6%   783 47.9%
   Unknown 253 26.8% 175 25.3%   152 29.1% 225 29.6%   428 26.2%
Combined Allele Analysis      1 × 10 -4      0.001   
   Wild Type 549 58.1% 336 48.6%   311 59.6% 384 50.5%   885 54.1%
   Carrier of ≥ 1 risk allele 396 41.9% 355 51.4%   211 40.4% 377 49.5%   751 45.9%
R702W Polymorphism      0.12      0.34   
   Wild Type (C/C) 776 82.1% 540 78.1%   429 82.2% 608 79.9%   1316 80.4%
   Heterozygote for risk allele (C/T) 153 16.2% 134 19.4%   85 16.3% 133 17.5%   287 17.5%
   Homozygote for risk allele (T/T) 16 1.7% 17 2.5%   8 1.5% 20 2.6%   33 2.0%
G908R Polymorphism      0.93      0.12   
   Wild Type (G/G) 858 90.8% 626 90.6%   475 91.0% 689 90.5%   1484 90.7%
   Heterozygote for risk allele (G/C) 84 8.9% 62 9.0%   47 9.0% 66 8.7%   146 8.9%
   Homozygote for risk allele (C/C) 3 0.3% 3 0.4%   0 0.0% 6 0.8%   6 0.4%
1007fs Polymorphism      1 × 10 -4      7 × 10 -6   
   Wild Type (-/-) 735 77.8% 477 69.0%   420 80.5% 524 68.9%   1212 74.1%
   Heterozygote for risk allele (-/C) 174 18.4% 166 24.0%   88 16.9% 187 24.6%   340 20.8%
   Homozygote for risk allele (C/C) 36 3.8% 48 6.9%   14 2.7% 50 6.6%   84 5.1%