Role of faecal occult bloods in the diagnosis of iron deficiency anaemia

Abstract

Introduction: Iron deficiency anaemia is the most common cause of anaemia in the United Kingdom. Estimates suggest that 3-5% of men and postmenopausal women have Iron deficiency anaemia (IDA) with the level rising to 7% in elderly hospital in-patients. Previous studies demonstrated abnormalities in up to 50% of patients with Iron deficiency anaemia, with a prevalence of carcinoma, most commonly of the colon, but also stomach and oesophagus of 10-20%. Current recommendations of BSG and AGA suggest performing OGD and Colonoscopy in all men and postmenopausal women with IDA. However many of the patients are elderly and investigations carries significant morbidity and mortality. A number of strategies such a multivariate analysis of patients characteristics and faecal calprotectin have to tested to predict the presence of significant endoscopic findings but lack sufficient sensitivity and specificity to make them of clinical value. Objective: To determine whether faecal occult blood (FOB) testing is able to predict the presence of significant findings in OGD and Colonoscopy in patients with IDA. Design: 318 patients aged 20 and older, referred for the investigation of IDA. Information was collected from all the patient regarding Haemoglobin , Mean Corpuscular Volume (MCV), Age, Sex , symptomatology and medication. All patients had 3 haemoccult and 3 lab guaiac FOB's tests and had OGD & Colonoscopy. Result: 36 patients were diagnosed with carcinoma (Colon 34, Gastro-oesophageal 2). By univariate analysis, only FOB (P <0.0001), abdominal pain (P< 0.025), and age (P<0.05) were significant. By multivariate analysis only FOB positive (P <0.0001) was significant. Further analysis showed that 182 (57.2%) patients were positive for either lab guaiac or haemoccult blood test and 33 of these had colon cancer, representing a 18.7% prevalence . 136 (42.76%) patients were negative for both FOBs ( traces positivity was ignored) and only 1 had colon cancer representing a 0.7% prevalence. Conclusions: Our findings show a high prevalence of significant findings on OGD and Colonoscopy in patients with IDA who have positive FOB tests. IDA patients who have negative FOB tests have a very low prevalence of cancer, and invasive investigation could potentially be avoided in this group.