Irritable bowel syndrome and chronic fatigue in a group of individuals exposed to Giardia infection during an outbreak 3 years earlier and a control group who did not contract the infection
| Condition | Exposed (n=817) No (%) | Controls (n=1128) No (%) | Unadjusted | Adjusted* |
| RR (95% CI) | RR (95% CI) | |||
| IBS | 355 (46.1) | 155 (14.0) | 3.3 (2.8 to 3.9) | 3.4 (2.9 to 3.8) |
| Severe IBS† | 106 (13.8) | 30 (2.7) | 5.1 (3.4 to 7.5) | 5.1 (3.6 to 7.2) |
| Frequent IBS‡ | 170 (22.1) | 42 (3.8) | 5.8 (4.2 to 8.0) | 6.2 (4.5 to 8.3) |
| Chronic fatigue | 366 (46.1) | 134 (12.0) | 3.8 (3.2 to 4.6) | 4.0 (3.5 to 4.5) |
| Severe chronic fatigue§ | 120 (15.1) | 24 (2.1) | 7.0 (4.6 to 10.8) | 7.4 (4.9 to 10.9) |
| Consistent chronic fatigue¶ | 141 (17.8) | 55 (4.9) | 3.6 (2.7 to 4.9) | 3.6 (2.6 to 4.7) |
| Both IBS and chronic fatigue | 216 (28.6) | 49 (4.5) | 6.4 (4.8 to 8.6) | 6.8 (5.3 to 8.5) |
| Only IBS | 129 (17.1) | 104 (9.5) | 1.8 (1.4 to 2.3) | 1.8 (1.4 to 2.3) |
| Only chronic fatigue | 125 (16.6) | 85 (7.7) | 2.1 (1.7 to 2.8) | 2.2 (1.7 to 2.8) |
↵* Adjusted for gender, age, level of education, main occupation, being a student during the outbreak.
↵† Severe IBS is IBS limiting daily activities often.
↵‡ Frequent IBS is IBS with pain more than 1 day a week.
↵§ Severe fatigue is chronic fatigue and total fatigue score ≥23.
↵¶ Consistent fatigue is chronic fatigue with symptoms 75% of the time or more.
IBS, irritable bowel syndrome.