In this week's PLoS Medicine, Anoop Shah of University College London and colleagues report that, in people with stable coronary disease, there were threshold haemoglobin values below which mortality increased in a graded, continuous fashion. As well as a systematic review and statistical analysis of previous studies, the researchers conducted a retrospective analysis of patients from a prospective observational cohort.
Their findings suggest that there are thresholds of haemoglobin that are associated with increased risk of mortality in patients with angina or myocardial infarction, and, though limited by the observational nature of its results, the study supports the rationale for conducting future randomised controlled trials to assess whether haemoglobin levels are causal and whether clinicians should intervene to increase haemoglobin levels, for example by oral iron supplementation.
The authors say that "Irrespective of a possible causal, reversible relationship between
haemoglobin concentration and mortality, further research is warranted to assess what incremental prognostic value haemoglobin might offer in risk stratifying patients with stable coronary disease."
Funding: This study is based on data from the Full Feature General Practice Research Database obtained under a Medical Research Council license from the UK Medicines and Healthcare Products Regulatory Agency (http://www.mrc.ac.uk/). This study was supported by grants from the UK National Institute for Health Research (RP-PG-0407-10314; http://www.nihr.ac.uk/) and the Wellcome Trust (086091/Z/08/Z; http://www.wellcome.ac.uk/). ADH is supported by a British Heart Foundation Senior Research Fellowship (FS05/125; http://www.bhf.org.uk/). KRA is partly funded by the UK National Institute for Health Research as a Senior Investigator (NF-SI-0508-10061). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The interpretation and conclusions contained in this study are those of the authors alone.
Competing Interests: The authors declare no competing interests.
Citation: Shah AD, Nicholas O, Timmis AD, Feder G, Abrams KR, et al. (2011) Threshold Haemoglobin Levels and the Prognosis of Stable Coronary Disease: Two New Cohorts and a Systematic Review and Meta-Analysis. PLoS Med 8(5): e1000439. doi:10.1371/journal.pmed.1000439
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