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.

Abstract

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. 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. 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 ≥ 37.5kg/m2 are consistently associated with lower scores at 6months. 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.