Association between preoperative anaemia and blood transfusion with long-term functional and quality of life outcomes amongst patients undergoing primary total knee arthroplasty in Singapore: a single-centre retrospective study.

PURPOSE: Preoperative anaemia affects up to one-third of patients undergoing total knee arthroplasty (TKA) and is associated with increased blood transfusion and prolonged hospitalisation. Prior studies have associated preoperative anaemia with poorer functional recovery after total hip arthroplasty. However, the association between preoperative anaemia and functional outcomes following TKA is unknown. We aim to determine whether preoperative anaemia and perioperative blood transfusion affect health-related quality of life (HRQoL) and functional outcomes following TKA. METHODS: Retrospective analysis of 1994 patients who underwent primary unilateral TKA from 2013 to 2014 was performed. Anaemia was defined according to the World Health Organisation definition. Baseline and 6-month postoperative HRQoL was assessed with the 36-Item Short Form Survey (SF-36), while function was assessed with Oxford Knee Score (OKS) and Knee Society Function Score (KSFS). Physical function (PF), role physical (RP), bodily pain (BP), social function (SF) and role emotional (RE) domains of SF-36, OKS and KSFS demonstrated significant change greater than the minimal clinically important difference between baseline and 6 months. Analysis of covariance (ANCOVA) was performed to identify predictors of 6-month scores. RESULTS: The incidence of preoperative anaemia was 22.3%. 4.3% of patients received blood transfusions. Preoperative anaemia and perioperative blood transfusion did not significantly affect SF-36, KSFS and OKS scores at 6 months postoperatively. Poor baseline SF-36, KSS and OKS scores and high BMI ≥ 37.5 kg/m2 are consistently associated with lower scores at 6 months. CONCLUSION: Preoperative anaemia and perioperative blood transfusion did not significantly affect HRQoL and functional outcomes following primary TKA. Poor baseline and obesity were associated with poorer outcomes.

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.