Application of NICE guideline NGI2 to the initial assessment of patients with lower gastrointestinal symptoms: not FIT for purpose?

摘要

Background: The National Institute for Health and Care Excellence (NICE) published NGI2 in 2015. The referral criteria for suspected colorectal cancer (CRC) caused controversy, because tests for occult blood in faeces were recommended. Faecal immunochemical tests for haemoglobin (FIT), which estimate faecal haemoglobin concentrations (f-Hb), might more than fulfil the intentions. Our aim was to compare the utility of f-Hb as the initial investigation with the NICE NGI2 symptom-based guidelines. Methods: Data from three studies were included. Patients had sex, age, symptoms, f-Hb and colonoscopy and histology data recorded. Sensitivity, specificity, positive (PPV) and negative predictive value (NPV) of f-Hb and NGI2 were calculated for all significant colorectal disease (SCD: CRC, higher risk adenoma and inflammatory bowel disease). Overall diagnostic accuracy was also estimated by the area under the receiver operating characteristic curve (AUC). Results: A total of 1514 patients were included. At a cut-off of ≥10 μg Hb/g faeces, the sensitivity of f-Hb for CRC was 93.3% (95% confidence interval (Cl): 80.7-98.3) with NPV of 99.7% (95%CI: 99.2-99.9). The sensitivity and NPV for SCD were 63.2% (95%CI: 56.6-69.4) and 96.0% (95%CI: 91.4-94.4), respectively. The NGI2 sensitivity and NPV for SCD were 58.4% (95%CI: 51.8-64.8) and 87.6% (95%CI: 85.0-89.8), respectively. The AUC for CRC was 0.85 (95% Cl: 0.87-0.90) for f-Hb versus 0.65 (95%CI: 0.58-0.73) for NG12 (P < 0.005). For SCD, the AUC was 0.73 (95%CI: 0.69-0.77) for f-Hb versus 0.56 (95%CI: 0.52-0.60) for NGI2 (P< 0.0005). Conclusion: f-Hb provides a good rule-out test for SCD and has significantly higher overall diagnostic accuracy than NG 12.