Published diagnostic models safely excluded colorectal cancer in an independent primary care validation study.

OBJECTIVE: To validate published diagnostic models for their ability to safely reduce unnecessary endoscopy referrals in primary care patients suspected of significant colorectal disease. STUDY DESIGN AND SETTING: Following a systematic literature search, we independently validated the identified diagnostic models in a cross-sectional study of 810 Dutch primary care patients with persistent lower abdominal complaints referred for endoscopy. We estimated diagnostic accuracy measures for colorectal cancer (N = 37) and significant colorectal disease (N = 141; including colorectal cancer, inflammatory bowel disease, diverticulitis, or >1-cm adenomas). RESULTS: We evaluated 18 models-12 specific for colorectal cancer-, of which most were able to safely rule out colorectal cancer: the best model (National Institute for Health and Care Excellence-1) prevented 59% of referrals (95% confidence interval [CI]: 56-63%), with 96% sensitivity (95% CI: 83-100%), 100% negative predictive value (NPV; 95% CI: 99-100%), and an area under the receiver operating characteristics curve (AUC) of 0.86 (95% CI: 0.80-0.92). The models performed less for significant colorectal disease: the best model (Brazer) prevented 23% of referrals (95% CI: 20-26%), with 95% sensitivity (95% CI: 90-98%), 96% NPV (95% CI: 92-98%), and an AUC of 0.73 (95% CI: 0.69-0.78). CONCLUSION: Most models safely excluded colorectal cancer in many primary care patients with lower gastrointestinal complaints referred for endoscopy. Models performed less well for significant colorectal disease.

Is there an added value of faecal calprotectin and haemoglobin in the diagnostic work-up for primary care patients suspected of significant colorectal disease? A cross-sectional diagnostic study.

BACKGROUND: The majority of primary care patients referred for bowel endoscopy do not have significant colorectal disease (SCD), and are - in hindsight - unnecessarily exposed to a small but realistic risk of severe endoscopy-associated complications. We developed a diagnostic strategy to better exclude SCD in these patients and evaluated the value of adding a faecal calprotectin point-of-care (POC) and/or a POC faecal immunochemical test for haemoglobin (FIT) to routine clinical information. METHODS: We used data from a prospective diagnostic study in SCD-suspected patients from 266 Dutch primary care practices referred for endoscopy to develop a diagnostic model for SCD with routine clinical information, which we extended with faecal calprotectin POC (quantitatively in µg/g faeces) and/or POC FIT results (qualitatively with a 6 µg/g faeces detection limit). We defined SCD as colorectal cancer (CRC), inflammatory bowel disease, diverticulitis, or advanced adenoma (>1 cm). RESULTS: Of 810 patients, 141 (17.4 %) had SCD. A diagnostic model with routine clinical data discriminated between patients with and without SCD with an area under the receiver operating characteristic curve (AUC) of 0.741 (95 % CI, 0.694-0.789). This AUC increased to 0.763 (95 % CI, 0.718-0.809; P = 0.078) when adding the calprotectin POC test, to 0.831 (95 % CI, 0.791-0.872; P < 0.001) when adding the POC FIT, and to 0.837 (95 % CI, 0.798-0.876; P < 0.001) upon combined extension. At a ≥ 5.0 % SCD probability threshold for endoscopy referral, 30.4 % of the patients tested negative based on this combined POC-tests extended model (95 % CI, 25.7-35.3 %), with 96.4 % negative predictive value (95 % CI, 93.1-98.2 %) and 93.7 % sensitivity (95 % CI, 88.2-96.8 %). Excluding the calprotectin POC test from this model still yielded 30.1 % test negatives (95 % CI, 24.7-35.6 %) and 96.0 % negative predictive value (95 % CI, 92.6-97.9 %), with 93.0 % sensitivity (95 % CI, 87.4-96.4 %). CONCLUSIONS: FIT - and to a much lesser extent calprotectin - POC testing showed incremental value for SCD diagnosis beyond standard clinical information. A diagnostic strategy with routine clinical data and a POC FIT test may safely rule out SCD and prevent unnecessary endoscopy referral in approximately one third of SCD-suspected primary care patients. Please see related article: http://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-016-0694-3 .

Application of the Rome III criteria is not likely to reduce the number of unnecessary referrals for colonoscopy in primary care.

OBJECTIVE: To determine to what extent the Rome III criteria for irritable bowel syndrome can contribute towards safely reducing unnecessary referrals for colonoscopy in primary care patients with lower gastrointestinal (GI) complaints. DESIGN: Data from the CEDAR study were used: a cross-sectional study in 810 patients with lower GI complaints suggestive for organic bowel disease who were referred by their general practitioner for secondary care colonoscopy. Fulfilment of the Rome III criteria was ascertained by a questionnaire. General practitioners recorded the presence or absence of alarm symptoms. Outcome was determined by colonoscopy and histology. RESULTS: Of 810 participants, 222 fulfilled the Rome III criteria [27%, 95% confidence interval (CI) 24-31%]. The majority of these patients presented with alarm symptoms. Only 39 participants fulfilled the Rome III criteria and lacked alarm symptoms (overall frequency 5%, 95% CI 4-7). Overall, organic bowel disease was diagnosed in 141 participants (17%). Participants who fulfilled the Rome III criteria had a significantly lower risk of organic bowel disease compared with participants who did not [12% (95% CI 8-17) vs. 20% (95% CI 17-23), P<0.01]. The lowest risk was observed in patients without alarm symptoms who fulfilled the Rome III criteria (3%, 95% CI 0-14). CONCLUSION: A minority of referred primary care patients with lower GI complaints both fulfilled the Rome III criteria for irritable bowel syndrome and lacked alarm symptoms. Although organic bowel disease could be ruled out safely in this small group, application of the Rome III criteria is not likely to lead to a considerable reduction in unnecessary referrals for colonoscopy in these patients.

Diagnostic accuracy of point-of-care fecal calprotectin and immunochemical occult blood tests for diagnosis of organic bowel disease in primary care: the Cost-Effectiveness of a Decision Rule for Abdominal Complaints in Primary Care (CEDAR) study.

BACKGROUND: Fecal biomarker tests that differentiate between organic bowel disease (OBD) and non-OBD in primary care patients with persistent lower-abdomen complaints could reduce the number of unnecessary referrals for endoscopy. We quantified the accuracy of fecal calprotectin and immunochemical occult blood (iFOBT) point-of-care (POC) tests and a calprotectin ELISA in primary care patients with suspected OBD. METHODS: We performed biomarker tests on fecal samples from 386 patients with lower-abdomen complaints suggestive for OBD. Endoscopic and histological diagnosis served as reference. RESULTS: OBD was diagnosed in 99 patients (prevalence 25.9%); 19 had adenocarcinoma, 53 adenoma, and 27 inflammatory bowel disease. Sensitivity for OBD was 0.64 (95% CI 0.54-0.72) for calprotectin POC, 0.56 (0.46-0.66) for iFOBT POC, and 0.74 (0.65-0.82) for calprotectin ELISA; specificities were 0.53 (0.48-0.59), 0.83 (0.78-0.87), and 0.47 (0.41-0.53), respectively. Negative predictive values (NPVs) were 0.81 (0.74-0.86), 0.85 (0.80-0.88), and 0.84 (0.78-0.89); positive predictive values (PPVs) varied from 0.32 (0.26-0.39) and 0.33 (0.27-0.39) (calprotectin tests) to 0.53 (0.44-0.63) (iFOBT POC). Combining the 2 POC tests improved sensitivity [0.79 (0.69-0.86)] and NPV [0.87 (0.81-0.91)] but lowered specificity [0.49 (0.44-0.55)] and PPV [0.35 (0.29-0.42)]. When adenomas ≤1 cm were considered non-OBD, the NPV of all tests improved to >0.90 [combined POC tests, 0.97 (0.93-0.99)]. CONCLUSIONS: Diagnostic accuracy of the tests alone or combined was insufficient when all adenomas were considered OBD. When only adenomas >1 cm were considered OBD, all tests could rule out OBD to a reasonable extent, particularly the combined POC tests. The tests were less useful for inclusion of OBD.

Diagnostic performance of rapid tests for detection of fecal calprotectin and lactoferrin and their ability to discriminate inflammatory from irritable bowel syndrome.

BACKGROUND: Ruling out somatic bowel disease, such as inflammatory bowel disease (IBD), is an important goal in the management of abdominal complaints. Endoscopy is commonly used but is invasive and expensive. Mucosal inflammation in IBD can be detected through fecal biomarkers, though the present enzyme-linked immunoabsorbent assay (ELISA) tests require laboratory facilities. We validated the diagnostic performance of two new fecal rapid tests (FRTs) for the detection of calprotectin and lactoferrin and assessed their potential to differentiate IBD from irritable bowel syndrome (IBS). METHODS: The calprotectin and lactoferrin FRTs and ELISA tests were performed on the fecal samples of 114 patients referred for endoscopy, 80% of whom had IBS and 20% IBD, and validated against the endoscopic diagnosis. RESULTS: The sensitivity and negative predictive value of the calprotectin FRT were both 100%, whereas they were 78% and 95%, respectively, for the lactoferrin FRT. The specificity and positive predictive value were slightly higher for the lactoferrin FRT. Both FRTs had similar diagnostic accuracy as the corresponding ELISA tests. CONCLUSIONS: The calprotectin and lactoferrin rapid tests are as good as the ELISA tests in detecting colonic inflammation. Given their simple use, FRTs can support the non-invasive exclusion of IBD, notably in primary care.