Table 3

Sensitivity and stratified analyses of pooled relative risk for cohort studies
Ulcerative colitis Crohn’s disease
Stratified analysis Meta-regression Stratified analysis Meta-regression
No. of studies No. of cases Pooled RR (95%CI) Heterogeneity (p-value) Coef. P value No. of studies No. of cases Pooled RR (95%CI) Heterogeneity (p-value) Coef. P value
Crude 18 6901 1.19(1.03, 1.36) <.001 21 6514 1.50(1.30, 1.72) <.001
Definition of urban/rural environment
Urban/rural defined 13 5906 1.18(1.09, 1.27) .19 16 5741 1.28(1.14, 1.43) <.001
Urban defined as >10,000 3 299 1.16(0.90, 1.50) .65 4 488 1.38(0.97, 1.97) .072
Year of publication
1962-1988 3 860 0.96(0.60, 1.51) <.001 0.16 .30 6 825 1.90(1.27, 2.85) <.001 −0.095 .47
1989-1998 9 3459 1.23(0.95, 1.57) <.001 9 3176 1.26(1.04, 1.53) <.001
1999-2009 6 2612 1.30(1.10, 1.54) .022 6 2513 1.49(1.18, 1.87) .001
Region
European countries 15 5036 1.21(0.99, 1.46) <.001 0.008 .98 17 4295 1.55(1.28, 1.88) <.001 0.77 .75
Non-European countries 3 1895 1.13(1.06, 1.22) .61 4 2219 1.39(1.18 1.62) .12
European Countries
Northern 6 3819 0.97(0.75, 1.27) <.001 −0.26 .086 9 3499 1.23(1.04, 1.45) <.001 0.23 .04
Eastern 2 723 1.59(0.98, 2.59) .013 2 297 2.30(0.54, 9.82) <.001
Mediterranean 6 458 1.39(0.82, 2.36) <.001 4 346 2.64(1.50, 4.62) .02
Western 1 36 2.12(1.00, 4.50) NA 2 153 1.72(1.17, 2.51) .79

Soon et al.

Soon et al. BMC Gastroenterology 2012 12:51   doi:10.1186/1471-230X-12-51

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