Systematic review: Mortality associated with raised faecal immunochemical test and positive faecal occult blood results

Abstract

SummaryBackgroundFaecal haemoglobin (f‐Hb) testing is used in colorectal cancer (CRC) screening and increasingly to guide the investigation in patients with symptoms suggestive of CRC. Studies have demonstrated increased mortality with raised f‐Hb.AimsTo assess the association of raised f‐Hb with all‐cause, non‐CRC (any cause excluding CRC) and cause‐specific mortality.MethodsWe searched Medline and Embase on 9 February 2024 to identify papers reporting mortality after faecal immunochemical (FIT) or guaiac faecal occult blood tests (gFOBT). The primary outcome was all‐cause mortality following a positive compared to a negative test.ResultsThe search identified 3155 papers. Ten met the inclusion criteria: three reported gFOBT and seven reported FIT results, as screening tests. These reported a total of 14,687,625 f‐Hb results. Elevated f‐Hb was associated with an increased risk of all‐cause, non‐CRC and cause‐specific mortality including death from cardiovascular, digestive and respiratory diseases. Crude risk ratios for all‐cause mortality with a positive versus negative test were derived from six papers (three reporting gFOBT, three FIT). An increased risk was demonstrated in five, with RRs ranging from 1.11 (95% CI: 1.06–1.16) to 2.95 (95% CI: 2.85–3.05). For non‐CRC mortality risk, RRs ranged from 1.09 (95% CI: 1.04–1.15) to 2.79 (95% CI: 2.70–2.89). We did not perform meta‐analysis due to a limited number of papers reporting suitable results for each type of f‐Hb test.ConclusionsAll‐cause, non‐CRC and cause‐specific mortality appear higher in those with raised f‐Hb. Population‐based studies are warranted to elicit whether this association occurs in symptomatic patients.