Diagnosis and treatment of iron deficiency in medical inpatients at a Swiss tertiary university referral hospital: a retrospective observational cohort study of clinical practice.

Background: Iron deficiency anaemia is a common disease with a prevalence of up to 19.2% in populations at risk. However, the prevalence of iron deficiency (ID) in hospitalised patients is not well known. The aims of this retrospective, observational cohort study were to evaluate the current diagnostic procedures for, and treatment of, ID as well as to estimate the prevalence of undiagnosed ID in hospitalised patients at the division of internal medicine in a Swiss tertiary university referral centre.

Methods: Within a study period of 6 months, data from all patients hospitalised at the division of internal medicine were analysed for the presence of anaemia (defined as haemoglobin levels for males <130 g/l and for females <120 g/l) and ID (ferritin <15 µg/l or ferritin <50 µg/l and transferrin saturation <20%).

Results: A total of 2,781 hospitalisation cases were analysed (2,251 unique patients, male 55.5%, mean age 66.4 years). In 2,267 cases (81.5%) results of a red blood cell count were available. In 329 cases (14.5%) iron parameters (IP) were determined and 45 (13.7%) cases / unique patients with ID were detected. Among the remaining 1,938 cases without IP determination, statistical estimation predicted 103 (56-329) undiagnosed ID cases. In ID patients, the most prevalent diagnosis was heart failure (24.4%). Of these patients, 72.7% had haemorrhage-facilitating drugs on hospital admission or discharge.

Conclusion: Iron deficiency is common in internal medicine and up to two-thirds of cases may not be diagnosed. Every seventh patient who had iron parameters analysed was iron deficient and two-thirds of patients with ID were treated with intravenous iron.