Fecal Markers of Inflammation and Disease Activity in Pediatric Crohn Disease: Results from the ImageKids Study

Early Intestinal Ultrasound Response to Biologic Therapy Predicts Endoscopic Remission in Children with Ileal Crohn's Disease: Results from the Prospective Super Sonic Study

BACKGROUND AND AIMS

STRIDE-II recommends early biomarker targets for treatment optimization to achieve treat-to-target [T2T] endoscopic remission [ER] in Crohn's disease [CD]. The predictive capabilities of intestinal ultrasound [IUS] for T2T ER remain unknown. We aimed to evaluate IUS response to predict ER in children with CD.

METHODS

This was a prospective longitudinal cohort study of children with ileal [TI] CD initiating biologic therapy undergoing IUS, clinical disease activity, and C-reactive protein [CRP] assessments at baseline, week 8, 6 months, and T2T within 1 year. The primary outcome was the accuracy of optimal cut-points to predict TI ER [SES-CD ≤ 2] for change in bowel wall thickness [BWT] on IUS from baseline to week 8, and BWT at week 8. Area under the receiver operating curve [AUROC] analysis was performed and univariate analysis tested associations.

RESULTS

In total, 44 children (median age 13 [IQR 12-17] years, 29 [66%] biologic naïve) were included, and 29 [66%] achieved ER. A ≥18% decrease in TI BWT at week 8 predicted ER with an AUROC of 0.99 [95% CI 0.98-1.00], 100% sensitivity, 93% specificity, 97% positive predictive value, and 100% negative predictive value, superior to a ≥46% decrease in PCDAI (AUROC 0.67 [95% CI 0.49-0.84]) and ≥84% decrease in CRP (AUROC 0.49 [95% CI 0.31-0.67]) at week 8.

CONCLUSIONS

Early change in TI BWT on IUS is highly predictive of ER in children with CD and superior to symptoms and CRP. Our findings suggest that IUS could be used for treatment optimization and tight control to guide T2T strategies.

The role of fecal biomarkers in individuals with inflammatory bowel disease

INTRODUCTION

Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD) and Ulcerative Colitis (UC), is a relapsing and remitting condition. Noninvasive biomarkers have an increasingly important role in the diagnosis of IBD and in the prediction of future disease course in individuals with IBD. Strategies for the management of IBD increasingly rely upon close monitoring of gastrointestinal inflammation.

AREAS COVERED

This review provides an update on the current understanding of established and novel stool-based biomarkers in the diagnosis and management of IBD. It also highlights key gaps, identifies limitations, and advantages of current markers, and examines aspects that require further study and analysis.

EXPERT OPINION

Current noninvasive inflammatory markers play an important role in the diagnosis and management of IBD; however, limitations exist. Future work is required to further characterize and validate current and novel markers of inflammation. In addition, it is essential to better understand the roles and characteristics of noninvasive markers to enable the appropriate selection to accurately determine the condition of the intestinal mucosa.

Fecal Calprotectin Assay at an Early Stage of Treatment Can Be Used as a Surrogate Marker to Predict Clinical Remission and Mucosal Healing in Pediatric Crohn's Disease

PURPOSE

This study evaluated the predictive role of fecal calprotectin (FC) measured at an early stage of treatment for monitoring clinical remission (CR) after six months and endoscopic remission (ER) after one year of treatment in pediatric Crohn's disease (CD).

METHODS

This retrospective study included 45 patients who simultaneously underwent ileocolonoscopy and FC testing during follow-up. FC levels were measured before and after six weeks of treatment. CR was assessed after six months of treatment using Pediatric Crohn' s Disease Activity Index and acute-phase reactants. ER was assessed after one year using the Simple Endoscopic Score for Crohn's Disease.

RESULTS

Twenty-nine (64.4%) patients used oral prednisolone for remission induction and 16 (35.6%) patients used anti-tumor necrosis factor-alpha. Thirty (66.7%) patients achieved CR, while 24 (53.3%) achieved ER. The FC level measured after six weeks of treatment could predict CR (χ²=9.15, p=0.0025) and ER (χ²=12.31, p=0.0004). The δFC could predict CR (χ²=7.91, p=0.0049), but not ER (χ²=1.85, p=0.1738). With a threshold of ≤950.4 µg/g, FC at week six could predict CR with 76.7% sensitivity and 73.3% specificity. The area under the curve (AUC) was 0.769 (standard error 0.0773, p=0.0005). The same threshold predicted ER with 87.5% sensitivity and 71.4% specificity. The AUC was 0.774 (standard error 0.074, p=0.0002).

CONCLUSION

FC assay at an early stage of treatment can be used as a surrogate marker to predict CR and mucosal healing in pediatric CD.

Combination of serological biomarkers and clinical features to predict mucosal healing in Crohn's disease: a multicenter cohort study

PURPOSE

Mucosal healing (MH) has become the treatment goal of patients with Crohn's disease (CD). This study aims to develop a noninvasive and reliable clinical tool for individual evaluation of mucosal healing in patients with Crohn's disease.

METHODS

A multicenter retrospective cohort was established. Clinical and serological variables were collected. Separate risk factors were incorporated into a binary logistic regression model. A primary model and a simple model were established, respectively. The model performance was evaluated with C-index, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy. Internal validation was performed in patients with small intestinal lesions.

RESULTS

A total of 348 consecutive patients diagnosed with CD who underwent endoscopic examination and review after treatment from January 2010 to June 2021 were composed in the derivation cohort, and 112 patients with small intestinal lesions were included in the validation cohort. The following variables were independently associated with the MH and were subsequently included into the primary prediction model: PLR (platelet to lymphocyte ratio), CAR (C-reactive protein to albumin ratio), ESR (erythrocyte sedimentation rate), HBI (Harvey-Bradshaw Index) score and infliximab treatment. The simple model only included factors of PLR, CAR and ESR. The primary model performed better than the simple one in C-index (87.5% vs. 83.0%, p = 0.004). There was no statistical significance between these two models in sensitivity (70.43% vs. 62.61%, p = 0.467), specificity (87.12% vs. 80.69%, p = 0.448), PPV (72.97% vs. 61.54%, p = 0.292), NPV (85.65% vs. 81.39%, p = 0.614), and accuracy (81.61% vs. 74.71%, p = 0.303). The primary model had good calibration and high levels of explained variation and discrimination in validation cohort.

CONCLUSIONS

This model can be used to predict MH in post-treatment patients with CD. It can also be used as an indication of endoscopic surveillance to evaluate mucosal healing in patients with CD after treatment.

Guidance on the interpretation of faecal calprotectin levels in children

BACKGROUND

Faecal calprotectin (FCP) is a powerful tool to predict inflammatory bowel disease (IBD) in patients with gastrointestinal symptoms. In the paediatric patient population, the reference value of < 50 μg/g and the influence of age on FCP levels result in a high number of redundant investigations and specialist referrals. We assessed paediatric FCP levels, their diagnostic value and corresponding referral pathways from primary and secondary care.

METHODS

We analysed two cohorts from a precisely defined catchment area: one consisted of all FCPs measured in this area (n = 2788). The second cohort-a subset of the first cohort-consisted of FCP values and corresponding clinical data from children who were referred for possible IBD to our department (n = 373).

RESULTS

In the first cohort, 47% of FCP levels were > 50 μg/g, 15% were ≥ 250 μg/g. Children < 1y had significantly (p < 0.001) higher FCP than older children. In the second cohort, 6.7% of children with an FCP of < 250 μg/g (or 8.6% with an FCP of < 600 μg/g) had IBD-all featured symptoms suggestive of IBD (e.g. bloody diarrhoea, nocturnal abdominal pain, weight loss) or abnormal blood tests. 76% of patients in whom raised FCP (> 50 μg/g) was the sole reason for being referred for suspected IBD did not have IBD.

CONCLUSION

Children with an FCP < 600 μg/g and without matching symptoms suggestive of IBD are unlikely to have IBD. A higher FCP reference value may provide cost-effective improvement that could avoid redundant investigations and specialist referrals. A guideline for specialist referrals is proposed.

Fecal calprotectin in healthy children aged 4-16 years

Reference values of fecal calprotectin (fCP) have not been convincingly established in children. We aimed to investigate fCP concentrations in a larger population of healthy children aged 4–16 years to analyze more in depth the behavior of fCP in this age range and to determine if cut-off levels could be conclusively recommended. A prospective study was conducted to investigate fCP concentrations of healthy children aged 4–16 years. In 212 healthy children, the median and 95th percentile for fCP were 18.8 mg/kg and 104.5 mg/kg, respectively. We found a statistically significant association between the 95th percentile of fCP concentrations and age (p < 0.001). We propose a nomogram to facilitate the interpretation of fCP results in children aged 4–16 years. Further studies are required to validate the proposed values in clinical practice.

Achieving Target Infliximab Drug Concentrations Improves Blood and Fecal Neutrophil Biomarkers in Crohn's Disease

BACKGROUND

The neutrophil fecal biomarkers, calprotectin (FCP) and lactoferrin (LCT), and peripheral blood neutrophil CD64 surface receptor (nCD64) are biomarkers for mucosal inflammation in inflammatory bowel disease (IBD). Although FCP has been evaluated as a biomarker for mucosal healing, cut points for LCT and nCD64 are less known. We aimed to identify the cut points for LCT and nCD64 that were associated with FCP remission, with a secondary aim to evaluate the relationship between biochemical outcomes and infliximab (IFX) trough concentrations.

METHODS

We analyzed FCP, LCT, and nCD64 before and after IFX induction in a pediatric Crohn's disease (CD) cohort study. Week-14 FCP biomarker remission was defined as FCP <250 µg/g, with clinical response defined as a weighted Pediatric Crohn's Disease Activity Index <12.5 or Δ>17.5 improvement. Predictive outcomes were calculated by receiver operating characteristics (ROCs).

RESULTS

Among 56 CD patients, ROC analysis identified an infusion 4 LCT <8.06 (area under the receiver operator characteristics [AUROC], 0.934, P < 0.001) and nCD64 <6.12 (AUROC, 0.76, P = 0.02) as the ideal cut points for week-14 FCP biomarker remission. End of induction IFX-trough of >9.4 µg/mL (AUROC, 0.799, P = 0.002) and >11.5 µg/mL (AUROC, 0.835, P = 0.003) were associated with a FCP <250 and FCP <100, respectively. We found patients achieving end of induction trough >5 µg/mL had a median FCP improvement (dose 1 to dose 4) of 90% compared with a median of 35% with levels <5 µg/mL (P = 0.024) with a similar median reduction in nCD64 (48% vs 20%, P = 0.031).

CONCLUSIONS

This study establishes cut points in neutrophil stool and blood biomarkers for both biochemical remission and therapeutic trough levels following induction therapy. Further studies that evaluate pharmacodynamic biomarker targets for endoscopic and histologic healing are warranted.