Background: A few recent studies suggested that anaemia has a marked impact on the survival of patients with coronary heart disease (CHD). However, all of these analyses did not take into consideration that chronic kidney disease (CKD) plays an important role in erythropoiesis and anaemia. Therefore, we assessed in this study whether anaemia is an independent predictor of mortality or if its impact was confounded by CKD, which is known to have itself a marked impact on outcomes of patients with CHD.
Methods: In a retrospective cohort study, we analysed 709 patients with symptomatic and significant CHD who underwent percutaneous coronary interventions. Patients were classified as anaemic using the WHO definition; renal function was classified by the estimated glomerular filtration rate (eGFR).
Results: In comparison with non-anaemic patients, anaemic patients had a significantly higher in-hospital mortality (4.9 vs 0.5%, P<0.001). Moreover, 1-year mortality rates of anaemic patients were significantly higher regardless of whether they had a normal eGFR (22 vs 2.8%, P=0.029), an eGFR of 60-89 ml/min (14 vs 4.2%, P<0.001), an eGFR of 30-59 ml/min (21 vs 3.7%, P<0.001) or an eGFR<30 ml/min (26 vs 0%, NS). When cumulative mortality was analysed by haemoglobin concentrations in steps of 1 g/dl from <11.0 g/dl to >16.9 g/dl, 1-year mortality rates were 28, 18, 15, 5.5, 3.8, 5.7, 1.5 and 0%, respectively (P<0.001, log rank). Even after adjustment for comorbidities by multivariable Cox regression models, haemoglobin remained a significant predictor of long-term mortality (hazard rate ratio 0.77, 95% confidence interval (CI): 0.62-0.82, P<0.001) while eGFR was not (hazard rate ratio 1.0, 95% CI: 0.99-1.01).
Conclusions: Anaemia was found to be a strong and independent predictor of acute and long-term mortality in patients with symptomatic CHD, regardless of the presence of CKD.