Data from: Prevalence of preoperative anemia, abnormal mean corpuscular volume and red cell distribution width among surgical patients in Singapore, and their influence on one year mortality

Introduction Preoperative anemia and high red cell distribution width
(RDW) are associated with higher perioperative mortality. Conditions with
high RDW levels can be categorized by mean corpuscular volume (MCV). The
relationship between RDW, anemia and MCV may explain causality between
high RDW levels and outcomes. We aim to establish the prevalence of
preoperative anemia and distribution of RDW and MCV among pre-surgical
patients in Singapore. In addition, we aim to investigate the association
between preoperative anemia, RDW and MCV levels with one-year mortality
after surgery. Methods Retrospective review of 97,443 patients aged
>= 18 years who underwent cardiac and non-cardiac surgeries under
anesthesia between January 2012 and October 2016. Patient demographics,
comorbidities, priority of surgery, surgical risk classification,
perioperative transfusion, preoperative hemoglobin, RDW, MCV were
collected. WHO anemia classification was used. High RDW was defined as
>15.7%. Multivariate regression analyses were done to identify
independent risk factors for mild or moderate/severe anemia and high RDW
(>15.7). Multivariate cox regression analysis was done to determine
the effect of preoperative anemia, abnormal RDW and MCV values on 1-year
mortality. Results Our cohort comprised of 94.7% non-cardiac and 5.3%
cardiac surgeries. 88.7% of patients achieved 1 year follow-up. Anemia
prevalence was 27.8% - mild anemia 15.3%, moderate anemia 12.0% and severe
anemia 0.5%. One-year mortality was 3.5%. Anemia increased with age in
males, while in females, anemia was more prevalent between 18-49 years and
>= 70 years. Most anemics were normocytic. Normocytosis and
macrocytosis increased with age, while microcytosis decreased with age.
Older age, male gender, higher ASA-PS score, anemia (mild- aHR 1.98;
moderate/severe aHR 2.86), macrocytosis (aHR 1.47), high RDW (aHR 2.34),
moderate-high risk surgery and emergency surgery were associated with
higher hazard ratios of one-year mortality. Discussion Preoperative anemia
is common. Anemia, macrocytosis and high RDW increases one year mortality.