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.引言 术前贫血与高红细胞分布宽度（red cell distribution width，RDW）均与更高的围手术期死亡率相关。可通过平均红细胞体积（mean corpuscular volume，MCV）对高RDW水平的病症进行分类。RDW、贫血与MCV之间的关联或可阐明高RDW水平与临床结局间的因果关系。本研究旨在明确新加坡术前患者的术前贫血患病率，以及RDW与MCV的分布情况；此外，本研究还将探讨术前贫血、RDW及MCV水平与术后1年死亡率之间的关联。 方法 本研究回顾性分析了2012年1月至2016年10月期间，97443名年龄≥18岁、接受麻醉下心脏手术与非心脏手术的患者。收集患者的人口学资料、合并症、手术优先级、手术风险分级、围手术期输血情况、术前血红蛋白、RDW及MCV水平。采用世界卫生组织（World Health Organization，WHO）贫血分级标准；将高RDW定义为RDW＞15.7%。通过多变量回归分析，明确轻度贫血、中度/重度贫血及高RDW（＞15.7%）的独立危险因素。采用多变量Cox回归分析，评估术前贫血、RDW异常及MCV异常对术后1年死亡率的影响。 结果 本研究队列中，94.7%为非心脏手术，5.3%为心脏手术；88.7%的患者完成了1年随访。贫血患病率为27.8%，其中轻度贫血占15.3%，中度贫血占12.0%，重度贫血占0.5%。术后1年死亡率为3.5%。男性贫血患病率随年龄增长而升高；女性则在18~49岁及≥70岁年龄段贫血患病率更高。多数贫血患者为正细胞性贫血。正细胞症与大细胞症的发生率随年龄增长而升高，而小细胞症的发生率随年龄增长而降低。高龄、男性、更高的美国麻醉医师协会身体状况（American Society of Anesthesiologists Physical Status，ASA-PS）评分、贫血（轻度贫血校正风险比[adjusted hazard ratio，aHR]为1.98；中度/重度贫血aHR为2.86）、大细胞症（aHR为1.47）、高RDW（aHR为2.34）、中高危手术以及急诊手术，均与更高的1年死亡率风险比相关。 讨论 术前贫血较为常见。贫血、大细胞症及高RDW均会升高术后1年死亡率。