Small bowel evaluation in asymptomatic fecal immunochemical test-positive patients with a negative colonoscopy: is it necessary?

Predicting pathology on small bowel capsule endoscopy: a good FIT

Background and study aims  Small bowel capsule endoscopy [SBCE) has an established role in investigating suspected small bowel bleeding [SSBB). Identification of a biomarker to predict pathology would maximize utility of this valuable diagnostic modality. This study aimed to investigate if fecal immunochemical test [FIT) could predict likelihood of small bowel pathology on SBCE. Patients and methods  Patients referred for SBCE to investigate anaemia or suspected small bowel bleeding were prospectively recruited. All patients had negative upper and lower endoscopy prior to referral. A FIT ≥ 45 ug Hb/g was considered positive. SBCE was positive if a potential source of SSBB was identified. The primary endpoint was correlation between FIT and positive SBCE. Secondary endpoints were correlation between anemia and SBCE and a combination of anemia plus FIT and SBCE. Results  Fifty-one patients were included in the final study cohort. 29.4 % had a positive FIT, 33.3 % were anemic, and 25.5 % patients had significant SBCE findings. There was a statistically significant association between positive FIT and pathology on SBCE (OR 12, 95 % CI [2.8 - 51.9), P  = 0.001). Sensitivity and specificity of positive FIT in predicting SBCE findings were 69 % and 84 %, respectively. A normal Hb had an NPV of 83 % (OR 0.30, P  = 0.09). Combining Hb and FIT was statistically significant in predicting pathology on SBCE (OR 9.14, 67 % PPV, 82 % NPV, P  = 0.025). Conclusion  FIT ≥ 45 ug Hb/g is a useful tool in predicting small bowel pathology on SBCE. Use of this biomarker alone, or in combination with serum haemoglobin, has value as a screening tool and may help to better triage patients referred for SBCE.

Luminally expressed gastrointestinal biomarkers

A biomarker is a measurable indicator of normal biologic processes, pathogenic processes or pharmacological responses. The identification of a useful biomarker is challenging, with several hurdles to overcome before clinical adoption. This review gives a general overview of a range of biomarkers associated with inflammatory bowel disease or colorectal cancer along the gastrointestinal tract. Areas covered: These markers include those that are already clinically accepted, such as inflammatory markers such as faecal calprotectin, S100A12 (Calgranulin C), Fatty Acid Binding Proteins (FABP), malignancy markers such as Faecal Occult Blood, Mucins, Stool DNA, Faecal microRNA (miRNA), other markers such as Faecal Elastase, Faecal alpha-1-antitrypsin, Alpha2-macroglobulin and possible future markers such as microbiota, volatile organic compounds and pH. Expert commentary: There are currently a few biomarkers that have been sufficiently validated for routine clinical use at present such as FC. However, many of these biomarkers continue to be limited in sensitivity and specificity for various GI diseases. Emerging biomarkers have the potential to improve diagnosis and monitoring but further study is required to determine efficacy and validate clinical utility.

Fecal occult blood testing for the prediction of small-bowel pathology detected by capsule endoscopy: a systematic review and meta-analysis

Background

Fecal occult blood testing (FOBT) has been suggested as a potential screening tool for small-bowel capsule endoscopy (CE). We conducted a meta-analysis of studies correlating FOBT and CE findings to examine the predictive value of positive FOBT for CE findings.

Methods

PubMed and Embase search. Sensitivity, specificity and diagnostic odds ratios (DORs) were calculated.

Results

Six studies were identified. Four used fecal immunochemical testing (FIT), one used FIT and guaiac FOBT, one used hemoglobin/haptoglobin complex testing (Hb/Hpt). Five of the 6 studies were suitable for statistical analysis. For all positive FOBT, sensitivity for small-bowel findings was 0.60 (95%CI 0.50-0.69), specificity was 0.72 (95%CI 0.52-0.86), and DOR was 3.96 (95%CI 1.50-10.4). For the 4 studies using only FIT, sensitivity was 0.48 (95%CI 0.36-0.61), specificity was 0.60 (95%CI 0.42-0.76), and DOR was 1.41 (95%CI 0.72-2.75).

Conclusions

Although a number of modalities have been suggested for screening small-bowel CE referrals, none of them, including FOBT, offer a comprehensive solution. Further work is required to refine screening methods for small-bowel CE referrals.