Clinical features of bowel disease in patients aged <50 years in primary care: a large case-control study

BACKGROUND: Incidences of colorectal cancer (CRC) and inflammatory bowel disease (IBD) are increasing in those aged <50 years. AIM: To identify and quantify clinical features in primary care of CRC/IBD in those aged <50 years. This study considered the two conditions together and aimed to determine which younger patients, presenting in primary care with symptoms, would benefit from investigation for potentially serious colorectal disease. DESIGN AND SETTING: Matched case-control study using primary care records from the Clinical Practice Research Datalink, UK. METHOD: = 22 947 IBD). Odds ratios (OR) and positive predictive values (PPV) were estimated for features of CRC/IBD in the year before diagnosis. 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 aged <50 years in primary care. Rectal bleeding and change in bowel habit are strongly predictive of CRC/IBD when combined with abnormal haematology. The present findings help prioritise patients for colonoscopy where the diagnosis is not immediately apparent.