| 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 | Â | Â | 21 | 6514 | 1.50(1.30, 1.72) | <.001 | Â | Â |
Definition of urban/rural environment | ||||||||||||
Urban/rural defined | 13 | 5906 | 1.18(1.09, 1.27) | .19 | Â | Â | 16 | 5741 | 1.28(1.14, 1.43) | <.001 | Â | Â |
Urban defined as >10,000 | 3 | 299 | 1.16(0.90, 1.50) | .65 | Â | Â | 4 | 488 | 1.38(0.97, 1.97) | .072 | Â | Â |
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 | Â | Â | 9 | 3176 | 1.26(1.04, 1.53) | <.001 | Â | Â |
1999-2009 | 6 | 2612 | 1.30(1.10, 1.54) | .022 | Â | Â | 6 | 2513 | 1.49(1.18, 1.87) | .001 | Â | Â |
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 | Â | Â | 4 | 2219 | 1.39(1.18 1.62) | .12 | Â | Â |
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 | Â | Â | 2 | 297 | 2.30(0.54, 9.82) | <.001 | Â | Â |
Mediterranean | 6 | 458 | 1.39(0.82, 2.36) | <.001 | Â | Â | 4 | 346 | 2.64(1.50, 4.62) | .02 | Â | Â |
Western | 1 | 36 | 2.12(1.00, 4.50) | NA | Â | Â | 2 | 153 | 1.72(1.17, 2.51) | .79 | Â | Â |