Not so FAST. Commentary on the article "Appraisal of the faecal haemoglobin, age and sex test (FAST) score in assessment of patients with lower bowel symptoms: an observational study".

A recent study by Digby et al. in BMC Gastroenterology evaluated the faecal haemoglobin, age and sex test (FAST) score in the assessment of patients with lower bowel symptoms attended in primary healthcare. This article is a valuable source of information but the conclusions must be carefully assessed. Authors evaluated the FAST score threshold with a 99% sensitivity (≥ 2.12) for colorectal cancer (CRC). Although the number of patients meeting this criteria is high, 53.5% of the patients not referred initially to secondary healthcare, the results on the patients referred to colonoscopy validate the prediction model. The sensitivity and the specificity for CRC detection were 99.0 and 23.2% with a positive and negative predictive value of 8.0 and 99.7%. Additionally, the sensitivity and the specificity for significant bowel disease were 96.1 and 26.2% with a positive and negative predictive value of 24.3 and 96.1%, consistent with our initial results. To conclude, although we need the information regarding the risk of CRC in those patients not referred to colonoscopy, a FAST Score < 2.12 allows to determine a group of patients with a low risk of CRC detection that requires no further evaluation.