In the good old days when we could have large meetings, Carlo DiLorenzo gave a terrific summary of recurrent abdominal pain (#NASPGHAN19 Postgraduate Course -part 3).  One of the slides, shown below, is supported by a new study (J Zeevenhooven et al. J Pediatr 2020; 219: 76-82)

In this recent reterospective study, the authors examined 853 patients, of whom 102 (12%) had an organic disorder; all had abdominal pain >2 months. The authors compared two diagnostic strategies:

• Group 1: anti-TTG IgA, fecal calprotectin, Giardia, along with blood tests (hemoglobin, CRP, ESR)
• Group 2: anti-TTG IgA, fecal calprotectin, and Giardia (if diarrhea)

Calprotectin was considered normal if <50 mcg/g,  “gray zone” if 51-250, mildly elevated if 251-1000, and elevated/active inflammation if >1000.

Key findings:

• Sensitivity of the strategies was 90% and 88% for Group 1 and Group 2 respectively
• In the presence of 1 or more alarm symptoms, the sensitivity was 92% for both strategies.
• The sensitivity/specificity of calprotectin varied based on the cutoff value.
  • For >50, the sensitivity 75%, specificity 87%, PPV 44%, and NPV 96%
  • For >250, the sensitivity 48%, specificity 99%, PPV 82%, and NPV 93%
  • For >1000, the sensitivity 38%, specificity 100%, PPV 98%, and NPV 92%

Alarm symptoms

• Alarm symptoms that were statistically different in the organic group included the following:
  • Chronic diarrhea (P <.001), occurred in 32% organic compared to 6% functional
  • GI blood loss (P <.001) , occurred in 35% organic compared to 5% functional
  • Recurrent vomiting (P=.029), occurred in 10% organic compared to 5% functional
  • Perianal complications (P=.001), occurred in 6% organic compared to 1% functional
  • Impaired growth (P=.023), occurred in 4% organic compared to 1% functional
• Interestingly, the study found that having a positive family history of IBD/celiac/FMF did not differentiate functional and organic patients, occuring in 12% and 15% respectively.
• Pain in RUQ or lower region also did not differentiate functional and organic patients, occuring in 3% and 4% respectively.
• The authors note that 30 (29%) patients with organic disease did not have an identified alarm symptom -this compares to 479 (64%) patients with functional disease did not have an identified alarm symptom

From my experience with our recent study (Digestive Diseases (Full Text): Diagnostic Yield Variation with Colonoscopy among Pediatric Endoscopists) which focused on diagnostic yield with colonoscopy, it is clear that there are significant limitations with data collection in a retrospective study regarding recurrent abdominal pain.  Even the definition of chronic diarrhea may vary considerably among practitioners.  At the same time, we did find that an abnormal calprotectin had the highest diagnostic yield (See related blog post for summary: Our Study: Provider Level Variability in Colonoscopy Yield)

It is surprising to me that only 10 patients (1%) in their cohort were identified as having impaired growth.

My take: This study shows that anti-TTG testing and calprotectin are the most useful tests in children with persistent abdominal pain.  The addition of hemoglobin, CRP, and ESR “can be left out in the clinical evaluation of chronic abdominal pain in children.”  The authors advocate, as well, for a prospective cohort study to confirm their observations.

Related blog posts:

• An Insurance Company Doing the Right Thing (with Calprotectin)
• Keep the Stool Cool for More Reliable Calprotectin Testing
• Calprotectin in Triaging Potential Pediatric IBD Cases
• Biomarkers identify patients who benefit and how
• Adverse Events Following Pediatric Endoscopy –Underestimated Previously
• Does negative testing reassure patients? | gutsandgrowth

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