Table 3. Environmental risk factors among cases and controls, and relatives affected with IBS and unaffected relatives.
| Cases (n = 477) | Controls (n = 297) | P value | Affected relatives (n = 424) | Unaffected relatives (n =1,705) | P value | |
|---|---|---|---|---|---|---|
| Cholecystectomy, n (%) | 122 (26) | 20 (7) | < 0.0001 | NA | NA | |
| Onset after surgery, n (%) | 55 (12) | 4 (7) | 0.2851 | NA | NA | |
| Intestinal infections, n (%) | 66 (14) | 10 (3) | < 0.0001 | 37 (9) | 83 (5) | 0.0014 |
| Onset after infection, n (%) | 34 (7) | 6 (11) | 0.3747 | 2 (3) | 6 (5) | 0.6100 |
| Abuse, n (%) | 162 (35) | 36 (13) | < 0.0001 | 139 (35) | 400 (25) | < 0.0001 |
| Diet allergy/sensitivity, n (%) | 326 (70) | 67 (23) | < 0.0001 | NA | NA | |
| Dairy, n (%) | 217 (46) | 23 (8) | < 0.0001 | NA | NA | |
| Caffeinated drinks, n (%) | 219 (46) | 18 (6) | < 0.0001 | NA | NA | |
| Carbonated drinks, n (%) | 185 (39) | 18 (6) | < 0.0001 | NA | NA | |
| Fruits and vegetables, n (%) | 149 (31) | 6 (2) | < 0.0001 | NA | NA | |
| Sweetened drinks, n (%) | 98 (21) | 4 (1) | < 0.0001 | NA | NA | |
| Depression or anxiety, n (%) | 230 (48) | 39 (13) | < 0.0001 | 180 (44) | 361 (22) | < 0.0001 |
IBS, irritable bowel syndrome; NA, not available.