Background and Objectives: Anaemia is a treatable common condition with various aetiologies and is prevalent in hospitalized patients. However, anaemia is inconsistently worked up and treated in the inpatient setting, in part because there is no standardized inpatient diagnostic and treatment approach to anaemia. Therefore, the objective of this study was to examine the diagnostic approach and prevalence of common aetiologies of anaemia in hospitalized patients and test for an association between aetiologies of anaemia and patient characteristics.

Materials and Methods: This study is a prospective observational study of hospitalized adult patients with anaemia. Patient laboratory data were used to assess the frequency of anaemia diagnostic workup and common aetiologies of anaemia.

Results: In a sample of 945 patients (mean age 58 years, 57% female and 72% Black), 30% patients had chronic anaemia, 11% had multifactorial anaemia, 5% had iron deficiency and 37% had insufficient laboratory data to determine their anaemia aetiology (unidentified aetiology). Patients with an unidentified aetiology received fewer transfusions and were more likely to be White, have longer hospital stays and have higher nadir haemoglobin levels.

Conclusion: A significant portion of hospitalized patients with anaemia did not have an identified aetiology. A standardized diagnostic algorithm could decrease this number and help patients receive appropriate treatment.