Evaluating inflammatory markers and Full Blood Count components for earlier detection of Significant Bowel Disease in Primary Care

Abstract

A retrospective observational study was conducted in adult patients from NHS Tayside who underwent blood and faecal testing via an established ‘Colorectal Bundle’. Patients subsequently referred to secondary care were identified and their clinical outcomes and faecal haemoglobin (f-Hb) results were recorded. Demographic information, including age, sex, smoking status, BMI, and SIMD quintile, was collected, and referral rates to secondary care were analysed according to f-Hb levels.

Full blood count (FBC) components - namely haemoglobin (Hb), platelet count, neutrophil count and lymphocyte count - were recorded, along with any ferritin and wide-range C-reactive protein (wrCRP) results. The neutrophil-to-lymphocyte ratio (NLR) and systemic immune-inflammation index (SII) were calculated.

Stored serum samples were analysed for additional analytes: wrCRP, interleukin-6 (IL-6), Tissue Inhibitor of Matrix Metalloproteinase-1(TIMP-1) and carcinoembryonic antigen (CEA) which were chosen for their availability and evidence of diagnostic value in significant bowel disease (SBD). The Siemens Healthineers IL-6 assay was verified on the Atellica analyser. The median values of the FBC components and the other analytes were calculated. CEA reference ranges for smokers and non-smokers were derived. The associations between these analytes and clinical outcome (colorectal cancer (CRC) and stages, inflammatory bowel disease (IBD) or no SBD) were assessed along with FBC components.

Receiver operating characteristic (ROC) curves and multiples of the median (MoMs) were calculated, and the correlations between SBD and various components of the FBC, NLR, SII and analytes were examined. Significant correlations were identified, suggesting added diagnostic potential.

A further group of patients with f-Hb ≥400 µgHb/g, referred for colonoscopy, was studied and FBC components were recorded to assess whether these would be useful to further triage patients perceived to have a higher risk of SBD.

Finally, an ‘Intelligent FIT’ profile was proposed, comprising of interpretative comments, an expansion of the existing Colorectal Bundle, and a proposed risk-score to support clinical decision making

Date of Award	2025
Original language	English
Awarding Institution	University of Dundee
Sponsors	Scottish Government & NHS Tayside Innovation Fund
Supervisor	Craig Mowat (Supervisor)