Table 2. Summary of receiver operating characteristic curve analysis.
NS = not specified; CI = confidence interval; CD = Crohn’s disease; UC = ulcerative colitis; IBD = inflammatory bowel disease; IBS = irritable bowel syndrome; OGID = organic gastrointestinal disease; FGID = functional gastrointestinal disease; YFCCP = York faecal calprotectin care pathway
| Author, year | Disease | Kit used | Reference standard | Cut-off value | Sensitivity | Specificity | AUC | Study quality |
| Wang et al., 2013 [12] | IBD vs non-IBD | ELISA BÜHLMANN Laboratories | Upper or lower endoscopy | 45.40 µg/g | 0.944 | 0.643 | 0.949 | High |
| Schoepfer et al., 2013 [13] | UC vs. healthy controls | ELISA PhiCal Test | Endoscopy based on the Modified Baron Score and the Lichtiger Clinical Activity Index | 57 µg/g | 91 | 90 | 0.939 (95% CI = 0.898–0.965) | High |
| Pavlidis et al., 2013 [24] | OGID vs. NOGID | BÜHLMANN, Calprotectin ELISA, EK-CAL | Endoscopy | 50 mg/g | 82% (95% CI = 73–89) | 77% (95% CI = 74–80) | 0.89 (0.85–0.93) | High |
| Chang et al., 2014 [25] | IBD vs. IBS | ELISA Quantum Blue LF‑CAL | Endoscopy with biopsies and radiological criteria | 50 mg/g | 62% | 95% | 0.931 ± 0.029 | High |
| Kolho et al., 2014 [26] | IBD and non-IBD | PhiCal ELISA | Upper and lower endoscopy | 59.5 μg/g | 81.8% (95% CI = 73.3–88.5) | 96.3 % (95 % CI = 81.0–99.9) | 0.944 (95 % CI = 0.907–0.981) | High |
| Caviglia et al., 2014 [27] | IBS vs. IBD | ELISA using polyclonal antibody | Colonoscopy with microscopic examination | 150 mg/g | 87.5% | 90.5% | 0.931 | High |
| Kennedy et al., 2015 [28] | IBD vs. IBS | ELISA | Upper or lower endoscopy (Lennard-Jones criteria for diagnosis of IBD and the Montreal criteria to classify clinical phenotype) | 100 μg/g | 96% | 87% | NS | Moderate |
| Kalantari et al., 2015 [29] | IBS vs. IBD | ELISA based on monoclonal antibodies | Colonoscopy | 164 µg/g | 57 (CI = 41%–71.6%) | 75 (CI = 59.7%–56.8%) | 0.67 | High |
| Dhaliwal et al., 2015 [30] | IBD vs. IBS | BÜHLMANN, PhiCal v1 and PhiCal v2 | Endoscopic, histological, and/or radiological confirmation | 50 µg/g | 88% | 78% | 0.84 (CI = 0.78–0.90) | High |
| Banarjee et al., 2015 [31] | IBD vs. IBS | Immunodiagnostik mono-clonal antibody-based ELISA | Colonoscopy with histological examination | 50 µg/g | 100% | 60% | NS | Moderate |
| Turvil et al., 2016 [14] | IBD vs. IBS | ELISA BÜHLMANN | Colonoscopy | 50 µg/g | NS | NS | 0.86 (95% CI = 0.77–0.95) | Moderate |
| Shitrit et al., 2017 [15] | CD vs. non-CD | ELISA IBD SCAN | Capsule endoscopy | 95 mg/kg | 77% | 73% | 0.767 | High |
| Moein et al., 2017 [16] | IBD vs. non-IBD | EK- CAL ELISA (BÜHLMANN) | Colonoscopy with histological examination | 78.4 µg/g | 100% | 100% | 1 | Moderate |
| Jha et al., 2018 [17] | UC vs. IBS | Phadia 100 Calprotectin | Colonoscopy based on Mayo score | 188 µg/g | 98.5% | 96.6% | 0.999 | High |
| Sharbatdaran et al., 2018 [18] | IBD vs. IBS | ELISA Buhlmann Laboratories Kit | Colonoscopy with histopathological examination | 127.65 µg/g | 73% | 89% | 0.83 (95% CI = 0.74–0.91) | High |
| Conroy et al., 2018 [19] | IBD vs. IBS | ELISA (Immundiagnostik) | Colonoscopy | 50 µg/g | 72.7% | 64.9% | 0.69 | High |
| Turvil et al., 2018 [20] | IBD vs. IBS | EK-CAL Calprotectin ELISA (BÜHLMANN) | Endoscopy | 100µg/g | 0.94 (0.85–0.98) | 0.92 (0.90–0.94) | NS | Moderate |
| Walker et al., 2018 [21] | OGID vs. FGID | ELISA (Immundiagnostik) | Colonoscopy | 100 µg/g | 64% | 90.1% | 0.93 (95% CI = 0.88–0.98) | Low |
| Turvill et al., 2020 [22] | YFCCP vs. non- YFCCP | ELISA | Colonoscopy | 100 µg/g | 90.6% (CI = 86–94) | 57.6% (54–61) | NS | Low |
| Chowdhury et al., 2021 [23] | IBD vs. IBS | BÜHLMANN Quantum Blue Reader ELISA | Endoscopy with histological and radiological findings | 50 µg/g | 91.1% | 86.7% | 0.959 (95% CI = 0.909–1.0) | High |