The prevalence of anaemia, hypochromia and microcytosis in preoperative cardiac surgical patients

This retrospective study aimed to determine the prevalence of preoperative anaemia, hypochromia and microcytosis in cardiac surgery patients. Data was analysed for 943 patients (over a two-year period) undergoing coronary artery bypass graft, valve or combined coronary artery bypass graft and valve surgery at a tertiary hospital in South Australia. Overall prevalence of preoperative anaemia was 25.2%, greater in males than females (27.6 vs 19.9%, P <0.01). Of patients with preoperative anaemia, 19.3% had reduced red cell indices (mean corpuscular haemoglobin and/or mean corpuscular volume) compared to 4% of patients without anaemia. The proportion of anaemic patients with low red cell indices was significantly higher in women <50 years and 50-65 years, compared to those >65 years of age (P=0.003). Anaemic patients with low red cell indices had lower preoperative haemoglobin than anaemic patients without low red cell indices (median haemoglobin 112 vs 120 g/l, P=0.008). Compared to non-anaemic patients, anaemic patients had higher transfusion rates (79.8 vs 46.4%, P <0.0001), which were greater in those with reduced red cell indices compared to those with normal red cell indices (93.5 vs 76.6%, P=0.01). This study demonstrated a high prevalence of preoperative anaemia, microcytosis and hypochromia in cardiac surgical patients.