Clinical features of bowel disease in primary care: a large case-control study
British Journal of General Practice
Royal College of General Practitioners
Reason for embargo
Background Colorectal cancer (CRC) and inflammatory bowel disease (IBD) incidences in the under-50s are increasing worldwide, including the UK. Aim To identify and quantify the clinical features in primary care of CRC/IBD in the under-50s. Design and Setting Matched case-control study using anonymised electronic primary care records from the Clinical Practice Research Datalink, UK. Methods Incident cases (aged <50 years) of CRC (n=1,661) and IBD (n=9,578) diagnosed between 2000 and 2013 were each matched with ≤3 controls (n=3,979 CRC; n=22,947 IBD) on age, sex and general practice. Odds ratios (OR) and positive predictive values (PPV) were estimated for features of CRC/IBD in the year before diagnosis. Results Ten features were independently associated (OR, 95% confidence interval) with CRC/IBD (all p<0.001): rectal bleeding (42, 33-55), change in bowel habit (27, 19-39), diarrhoea (8.9, 7.5-11), raised inflammatory markers (5.4, 4.6-6.3), thrombocytosis (4.4, 3.4-5.7) abdominal pain (3.9, 3.4-4.5), low mean cell volume (MCV) (2.7, 2.1-3.5), low haemoglobin (2.5, 2.1-3.1), raised white cell count (1.5, 1.3-1.9), and raised hepatic enzymes (1.4, 1.2-1.6). PPVs were >3% for rectal bleeding with diarrhoea, thrombocytosis, low MCV, low haemoglobin or raised inflammatory markers; for change in bowel habit with low MCV, thrombocytosis or low haemoglobin; and for diarrhoea with thrombocytosis. Conclusion This study quantified the risk of serious bowel disease in symptomatic patients <50 in primary care. Rectal bleeding and change in bowel habit are strongly predictive of CRC/IBD when combined with abnormal haematology. Our findings help prioritise patients for colonoscopy where the diagnosis is not immediately apparent.
This article presents independent research funded by the Policy Research Unit in Cancer Awareness, Screening and Early Diagnosis, which receives funding for a research programme from the Department of Health Policy Research Programme. It is a collaboration between researchers from seven institutions (Queen Mary University of London, UCL, King's College London, London School of Hygiene and Tropical Medicine, Hull York Medical School, Durham University and Peninsula Medical School/ University of Exeter). The views expressed are those of the authors and not necessarily those of the NHS, or the Department of Health.
This is the author accepted manuscript. The final version is available from the Royal College of General Practitioners via the DOI in this record.
Published online March 27, 2017