Routine use of oral iron for people with heart failure and iron deficiency in primary care; retrospective cohort study

Aims Iron deficiency is common among people with heart failure and associated with morbidity and mortality. While intravenous iron improves clinical outcomes, oral iron continues to be prescribed in routine practice despite limited evidence of benefit.

We completed a retrospective primary care cohort study (2016 to 2021) to investigate the proportion of people with an incident diagnosis of heart failure who had iron deficiency identified (defined as ferritin <100µg/L) and subsequently received a first prescription for oral iron within 12 months. Multivariable logistic regression was used to report the odds ratio (OR) of receiving oral iron in relation to key demographic covariates and co-morbidities.

Among 105,749 people with an incident diagnosis of heart failure, 35,688 underwent a ferritin test within the first year of whom 11,237 had iron deficiency and no prior prescription for oral iron. Of these, 2,734 (24.3%) were subsequently prescribed oral iron. Increasing age (OR per 10-year increase 1.14, 95%CI: 1.10-1.19), Asian ethnicity (1.33, 1.08-1.64), cirrhosis (2.01, 1.29-3.14) and diabetes (1.36, 1.24-1.49) were associated with increased odds of receiving oral iron. Among 1,357 (49.6%) people who had their ferritin level re-tested, the median change was 26 µg/L (interquartile range 7 to 61) among people who were prescribed oral iron compared to 4 µg/L (IQR −9 to 34) among people not prescribed oral iron.

One in four individuals with heart failure and low ferritin received oral iron replacement, despite this not being recommended in international guidelines. Treatment could be improved and standardised in primary care. Competing Interest Statement The authors have declared no competing interest. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Clinical Practice Research Datalink Research Data Governance process of the Medicines and Healthcare products Regulatory Agency gave ethical approval for this work (protocol number 22_001873). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability The data used in this study were obtained from the Clinical Practice Research Datalink (CPRD) under licence and cannot be shared directly by the authors. Access to CPRD data is subject to approval through the CPRD Research Data Governance process. Further information on data access is available from CPRD.