Comparison of clinical variables and biomarkers in patients diagnosed with inflammatory bowel disease and non-IBD
| Variable | N* | IBD n=13 | Non-IBD n=182 | P value† |
| Demographics | ||||
| Age | 195 | 15.5 (14.3–17.8) | 15.1 (11.4–17.1) | 0.23 |
| Gender (female) | 195 | 46% (6/13) | 46% (84/182) | 1 |
| Family history IBD | 187 | 33% (4/12) | 22% (39/175) | 0.48 |
| Symptoms | ||||
| Duration of symptoms (months) | 191 | 4.0 (2.0–8.0) | 6.0 (3.0–12.0) | 0.22 |
| Abdominal pain | 192 | 69% (9/13) | 89% (159/179) | 0.062 |
| Pain improves on defaecation | 178 | 27% (3/11) | 38% (64/167) | 0.54 |
| Number of stools in 24 hours | 188 | 4.0 (2.8–4.0) | 3.0 (1.8–4.2) | 0.48 |
| Diarrhoea (Bristol stool ≥6) | 137 | 64% (7/11) | 33% (41/126) | 0.050 |
| Change in stool frequency | 184 | 100% (13/13) | 74% (127/171) | 0.040 |
| Change in stool appearance | 181 | 100% (12/12) | 70% (119/169) | 0.039 |
| Rectal bleeding | 191 | 31% (4/13) | 22% (39/178) | 0.49 |
| Unintentional weight loss | 192 | 15% (2/13) | 18% (33/179) | 1 |
| Nocturnal symptoms | 188 | 46% (6/13) | 25% (43/175) | 0.11 |
| Blood biomarkers: continuous | ||||
| Haemoglobin (g/L) | 154 | 128 (112–134) | 137 (130–148) | 0.007 |
| White blood cell count (×109/L) | 154 | 8.3 (7.7–10.0) | 6.2 (5.1–7.7) | <0.001 |
| Platelet count (×109/L) | 154 | 265 (249–355) | 251 (221–298) | 0.14 |
| CRP (mg/L) | 145 | 17 (5–25) | <1 (<1–2) | <0.001 |
| Ferritin (μg/L) | 87 | 22.5 (15–48) | 41 (29–66.5) | 0.11 |
| Albumin (g/L) | 116 | 45 (38–49) | 48 (47–51) | 0.004 |
| B12 (ng/L) | 39 | 628 (273–700) | 442 (307–786) | 0.91 |
| Folate (μg/L) | 39 | 7.2 (6.0–10.2) | 9.6 (5.8–11.6) | 0.53 |
| Blood biomarkers: binary | ||||
| Anaemia‡ | 154 | 38% (5/13) | 7% (10/141) | 0.004 |
| Raised CRP (>5 mg/L) | 145 | 69% (9/13) | 5% (7/132) | <0.001 |
| Raised platelets (>400 µg/L) | 154 | 23% (3/13) | 2% (3/141) | 0.008 |
| Low ferritin§ | 83 | 88% (7/8) | 21% (16/75) | <0.001 |
| Raised white blood cell count** | 154 | 0% (0/13) | 5% (7/141) | 1 |
| Low B12 (<180 ng/L) | 39 | 0% (0/7) | 3% (1/32) | 1 |
| Stool biomarker | ||||
| Faecal calprotectin (μg/g) | 195 | 1140 (132–1605) | 21 (10–48) | <0.001 |
| Red-flag criteria ¶ | ||||
| Red-flag criteria present | 192 | 62% (8/13) | 54% (96/179) | 0.78 |
% (numerator/denominator); median (IQR).
*Denominator denoted by column N.
†P values represent Mann-Whitney U, χ² or Fisher’s exact test as appropriate.
‡Anaemia threshold: 4–12 years <115 g/L; males 12–18 <130 g/L; females 12–18 <120 g/L.
§Low ferritin threshold: If CRP >5 mg/L, then ferritin threshold <100 µg/L; if CRP ≤5 mg/L, then ferritin threshold 13 µg/L for females and 30 µg/L for males.
¶Red-flag criteria include one or more of: unintentional weight loss, rectal bleeding, family history of IBD.
**Raised white blood cell count threshold: female >11 × 109/L; male >10.6 × 109/L.
CRP, C reactive protein; IBD, inflammatory bowel disease.