Do other variables add value to assessment of the risk of colorectal disease using faecal immunochemical tests for haemoglobin?

Background: Faecal immunochemical tests for haemoglobin have been recommended to assist in assessment of patients presenting in primary care with lower bowel symptoms. The aim was to assess if, and which, additional variables might enhance this use of faecal immunochemical tests.

Methods: Faecal immunochemical test analysis has been a NHS Tayside investigation since December 2015. During the first year, 993 patients attending colonoscopy were invited to complete a detailed questionnaire on demographic background, symptoms, smoking status, alcohol use, dietary fibre, red and processed meat intake, physical activity, sitting time, dietary supplement use, family history of colorectal cancer, adenoma, inflammatory bowel disease and diabetes. Significant bowel disease was classified as colorectal cancer, advanced adenoma or inflammatory bowel disease.

Results: A total of 470 (47.3%) invitees agreed to complete the questionnaire and 408 (41.1%) did. Unadjusted odds ratios for the presence of significant bowel disease compared with undetectable faecal haemoglobin increased with increasing faecal haemoglobin and for faecal haemoglobin 10–49, 50–199, 200–399 and ⩾400 μg Hb/g faeces were 0.95 (95% CI: 0.16–5.63), 2.47 (0.55–1.03), 6.30 (1.08–36.65) and 18.90 (4.22–84.62), respectively. Rectal bleeding and family history of polyps were the only other variables with statistically significant (P < 0.05) odds ratios greater than 1.00, being 1.88 (1.13–3.17) and 2.93 (1.23–6.95), respectively. Odds ratios adjusted for all other variables showed similar associations, but only faecal haemoglobin and family history of polyps had significant associations.

Conclusions: Faecal haemoglobin is the most important factor to be considered when deciding which patients presenting in primary care with lower bowel symptoms would benefit most from referral for colonoscopy.