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P285 Is faecal immunochemical test a suitable alternative to faecal calprotectin in children?

K. SANDHU1, R. Ayling2, S. Naik1

1Royal London Hospital, Paediatric Gastroenterology, London, UK, 2Barts Health NHS Trust, Pathology, London, UK

Background

Faecal calprotectin (FCP) has widely been used as a non-invasive marker for intestinal inflammation in children. Faecal immunochemical test (FIT) is well established in bowel cancer screening programmes in adults. FIT is cost-effective and easier to handle in comparison to FCP. We aimed to evaluate the performance of FIT in the paediatric population and compare it with FCP.

Methods

Clinicians in paediatric gastroenterology clinic who requested FCP for further investigation. These patients provided a sample of FIT from the same stool. These samples were collected over a 10-month period from November 2018 to September 2019. FIT samples were taken into a proprietary tube (Eiken Chemical, Tokyo, Japan) and stored at 4°C until analysis. FCP was measured using Liason Calprotectin (Diasorin, Italy).

Results

131 samples were returned; 131 FIT and 102 FCP of which 7 calprotectin samples were insufficient for analysis. In 95 patients we had paired samples for FIT and FCP. The normal range for FCP was 0–200 µg/g and for FIT was 0–4 µg/g. Twenty-three of 95 patients were non-IBD (24.2%). In the IBD group; 42 had Crohn’s, 27 ulcerative colitis and 3 indeterminate colitis. 15 were new diagnosis of IBD. In the 95 patients; FIT was normal (<4 µg/g) in 50 patients and abnormal (>4 µg/g) in 45 patients. FCP was normal (<200 µg/g) in 45 patients and abnormal (>200 µg/g) in 50 patients. FIT positively correlated with calprotectin, Spearman’s rank coefficient 0.653, p < 0.001. There were 32 patients with FIT >20µg/g and in 29 of these patients, FCP was >200 µg/g. In 60 patients with FIT and in 35 patients with FCP underwent colonoscopies. Table 1 shows the diagnostic value of FIT in comparison to histological inflammation.

Table 1: FIT (n = 60).

FIT ≥ 4 µg/g
Sensitivity 81.3% (95% CI 68.1–89.8)
Specificity 91.7% (95% CI 64.6–98.5)
Positive predictive value 97.5% (95% CI 85.6–99.6)
Negative predictive value 55% (95% CI 39.8–69.3)

The correlation of FIT with histological findings are shown in Figure 1. All patients with normal histology had a FIT <4 µg/g. In 91.4% of patients with moderate to severe histological inflammation had a FIT >5 µg/g.

Figure 1. Shows correlation of FIT with histology findings. (a) Normal and mild inflammation (n = 25). (b) Moderate and severe inflammation (n = 35).

Conclusion

Our study is the first to compare FIT and FCP in the paediatric population. Our results suggest that FIT correlates well with FCP and can be used to differentiate between functional bowel disease and inflammation in children. A FIT of > 20 µg/g was consistent with the finding of severe inflammation.