Combining faecal haemoglobin, iron deficiency anaemia status, and age can improve colorectal cancer risk prediction in patients attending primary care with bowel symptoms: a retrospective observational study

TY - JOUR

T1 - Combining faecal haemoglobin, iron deficiency anaemia status, and age can improve colorectal cancer risk prediction in patients attending primary care with bowel symptoms

T2 - a retrospective observational study

AU - Digby, Jayne

AU - Nobes, Jenny

AU - Strachan, Judith

AU - Hall, Chris

AU - Fraser, Callum G.

AU - Mowat, Craig

N1 - © Author(s) (or their employer(s)) 2025.

PY - 2025/3/26

Y1 - 2025/3/26

N2 - Background: In primary care, National Institute for Health and Care Excellence suspected cancer guidelines recommend measuring faecal haemoglobin (f-Hb) if colorectal cancer (CRC) is suspected, with a referral threshold of ≥10 μg Hb/g faeces defining a 3% risk, but most have a normal colonoscopy. Objective: Examine whether combining f-Hb, patient age and iron-deficient anaemia (IDA) status improves risk prediction. Design: Retrospective single-centre observational study of symptomatic patients who submitted contemporaneous f-Hb and full blood count (FBC) samples between December 2015 and December 2019. f-Hb was estimated using HM-JACKarc (Hitachi Chemical Diagnostics Systems). Patients were categorised by presence/absence of IDA. Incident CRC was identified via record linkage to the Scottish Cancer Registry. Kaplan-Meier estimates determined cumulative 1-year CRC risk by patient age, f-Hb result and presence of IDA. Results: Of 34 647 valid f-Hb results retrieved; 7889 (22.8%) had f-Hb≥10 μg Hb/g. Of these, 33 285 samples (96.1%) had associated FBC results of which 3000 (9.0%) had IDA. Overall, 571 incident CRC were recorded. The risk of CRC breached 3% in patients with f-Hb>99 μg Hb/g aged >40 years and reached 30% (19.4-41.0) with f-Hb>99 μg Hb/g in age >55 years plus IDA. 2029 f-Hb results (25.7%) were in the 10-19 μg Hb/g range of which 27 (1.3%) had CRC. In this subgroup, CRC risk did not exceed 3% in patients <85 years and no IDA. Conclusion: Combining f-Hb, patient age and IDA status improves CRC risk prediction, identifies a low-risk group with f-Hb<20 μg Hb/g and no IDA and could inform revised referral guidance.

AB - Background: In primary care, National Institute for Health and Care Excellence suspected cancer guidelines recommend measuring faecal haemoglobin (f-Hb) if colorectal cancer (CRC) is suspected, with a referral threshold of ≥10 μg Hb/g faeces defining a 3% risk, but most have a normal colonoscopy. Objective: Examine whether combining f-Hb, patient age and iron-deficient anaemia (IDA) status improves risk prediction. Design: Retrospective single-centre observational study of symptomatic patients who submitted contemporaneous f-Hb and full blood count (FBC) samples between December 2015 and December 2019. f-Hb was estimated using HM-JACKarc (Hitachi Chemical Diagnostics Systems). Patients were categorised by presence/absence of IDA. Incident CRC was identified via record linkage to the Scottish Cancer Registry. Kaplan-Meier estimates determined cumulative 1-year CRC risk by patient age, f-Hb result and presence of IDA. Results: Of 34 647 valid f-Hb results retrieved; 7889 (22.8%) had f-Hb≥10 μg Hb/g. Of these, 33 285 samples (96.1%) had associated FBC results of which 3000 (9.0%) had IDA. Overall, 571 incident CRC were recorded. The risk of CRC breached 3% in patients with f-Hb>99 μg Hb/g aged >40 years and reached 30% (19.4-41.0) with f-Hb>99 μg Hb/g in age >55 years plus IDA. 2029 f-Hb results (25.7%) were in the 10-19 μg Hb/g range of which 27 (1.3%) had CRC. In this subgroup, CRC risk did not exceed 3% in patients <85 years and no IDA. Conclusion: Combining f-Hb, patient age and IDA status improves CRC risk prediction, identifies a low-risk group with f-Hb<20 μg Hb/g and no IDA and could inform revised referral guidance.

KW - bowel disease

KW - colorectal cancer

KW - faecal biomarkers

KW - faecal immunochemical test

KW - faecal haemoglobin

KW - full blood count

KW - age

KW - primary care

KW - AGEING

KW - PRIMARY CARE

KW - COLORECTAL CANCER

UR - https://www.scopus.com/pages/publications/105001531525

U2 - 10.1136/gutjnl-2024-334248

DO - 10.1136/gutjnl-2024-334248

M3 - Article

C2 - 40139747

SN - 0017-5749

JO - Gut

JF - Gut

ER -