The Prevalence of Anaemia, Hypochromia and Microcytosis in Preoperative Cardiac Surgical Patients

Abstract

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.

Iron deficiency and cardiovascular disease

“…Prevalence of preoperative anaemia was reported to be 25.2% in a sample of 943 patients undergoing cardiac surgery, and was higher in men than in women (27.6% versus 19.9%; P <0.01). 87 In a prospective, observational cohort study involving 165 anaemic patients undergoing elective cardiac surgery requiring cardiopulmonary bypass, functional iron deficiency was present in 78 patients (48%) preoperatively. 88 Absolute iron deficiency, with serum ferritin <15 μg/l in women and <22 μg/l in men, was present in 26 of these patients.…”

The exclusion of hypochromia from the iron deficiency screen

“…In David et al’s2 retrospective analysis of data from 943 adults, the overall prevalence of anemia was 25.2%, and the median age of the 238 anemic subjects was 73 years old. Among the 238 anemic subjects, the prevalence of hypochromia (characterized by MCH <27 pg) was 19.3%, and the prevalence of microcytosis (characterized by MCV <80 fl) was 5.9%.…”

“…When the screening strategy for iron deficiency makes use of mean corpuscular volume (MCV) to the exclusion of mean corpuscular hemoglobin (MCH), as was the case in the recent study by Radia et al1 there is a risk of repeating the mistakes highlighted in a retrospective analysis of the management of anemia, microcytosis, and hypochromia in preoperative subjects in South Australia 2…”

“…Among the 238 anemic subjects, the prevalence of hypochromia (characterized by MCH <27 pg) was 19.3%, and the prevalence of microcytosis (characterized by MCV <80 fl) was 5.9%. Among the 705 non-anemic subjects the prevalence of hypochromia and microcytosis was 3.8% and 1.9%, respectively 2. Had the flowchart for the Rapid Access Anemia Patient pathway depicted in Radia et al’s Figure 31 been followed, none of David et al’s2 patients with hypochromia (who were in the overwhelming majority) would have been further investigated.…”

“…Among the 705 non-anemic subjects the prevalence of hypochromia and microcytosis was 3.8% and 1.9%, respectively 2. Had the flowchart for the Rapid Access Anemia Patient pathway depicted in Radia et al’s Figure 31 been followed, none of David et al’s2 patients with hypochromia (who were in the overwhelming majority) would have been further investigated. In that study, regardless of either MCH or MCV status, none of the 238 anemic patients received the benefit of further investigation; notwithstanding the fact that the study by Jolobe had shown that iron deficiency, when characterized by serum ferritin <18 mcg/L, was more commonly associated with hypochromia than with microcytosis, and that in some patients (the majority), hypochromia occurred in the absence of microcytosis and, in others (the minority), the opposite was the case 3…”