Recently in PLoS Medicine, Anoop Shah of University College London and colleagues report that, in people with stable coronary disease, there were threshold hemoglobin 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 borderline low hemoglobin levels 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 randomized controlled trials to assess whether hemoglobin levels are causal and whether clinicians should intervene to increase hemoglobin 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” (Courtesy of EurekAlert!, a service of AAAS).

Reference: Shah AD, 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