A study comparing the risk of mortality associated with different practices of anaemia management among different dialysis centres in the US has been published in JAMA.

The authors note that the appropriate use of erythropoiesis-stimulating agents (ESAs) and intravenous iron can effectively manage the anaemia of chronic kidney disease and end-stage renal disease (ESRD).  Several trials have reported an increased risk of mortality and cardiovascular events in patients treated to achieve higher haematocrit levels – as these trials were conducted in selected patient populations however, some controversy around the management of anaemia in ESRD remains.    

The purpose of this trial was to address this evidence gap – the researchers sought to evaluate the safety of ESA and iron as they are prescribed routinely in practice, in an unselected population of patients with ESRD. As data were not available on the anaemia management protocols of individual dialysis centres, the researchers were not able to directly estimate the mortality associated with different protocols.  Instead they used data from Medicare’s ESRD program to estimate the management profile of every US dialysis centre (around 4,500), based on its typical use of ESAs and intravenous iron in haemodialysis patients within four haematocrit categories.  The predicted treatments were then correlated with 1-year mortality risk among patients initiating haemodialysis at each centre.

The main results were as follows (269,717 patients were included in the outcomes sample):

• Monthly mortality rates were highest in patients with haematocrit <30% (mortality, 2.1%) and lowest for those with haematocrit of ≥36% (mortality, 0.7%).

• After adjustment for baseline case-mix differences, dialysis centres that used larger ESA doses in patients with haematocrit <30% had lower mortality rates than centres that used smaller doses (hazard ratio [HR] 0.94; 95% CI 0.90-0.97).

• Centres that administered iron more frequently to patients with haematocrit <33% had lower mortality rates (highest vs lowest quintile: HR 0.95; 95% CI 0.91-0.98). However, centres that used larger ESA doses in patients with haematocrit between 33% and 35.9% had higher mortality rates (highest vs lowest quintile, HR, 1.07; 95% CI, 1.03-1.12).

• More intensive use of both ESAs and iron was associated with increased mortality risk in patients with haematocrit of ≥36%.

The authors conclude that there is evidence of decreased mortality risk associated with greater use of ESAs and iron in those with lower haematocrit levels.  While lower overall mortality risk occurs at higher haematocrit levels, greater use of ESAs and iron in these patients appears to be associated with an elevated mortality risk.  They note that the incident dialysis patient population make up only 20% of the overall haemodialysis population but have the highest mortality rates, therefore their results may not be generalisable to prevalent patients.