title: Routine pre-operative group cross-matching in total knee arthroplasty: A review of this practice in an Asian population.
abstract: BACKGROUND
  Routine pre-operative group cross-match (GXM) and post-operative haemoglobin level measurements are performed for all total knee arthroplasty (TKA) patients in many institutions. We aimed to determine whether this practice is justified, and to identify predictors for post-operative transfusion.
  
  
  METHODS
  A retrospective review was performed on 226 TKA procedures performed between Jan. 2011 and Dec. 2013. Patients' demographics and clinical details including co-morbidities, pre-operative laboratory results, type of anaesthesia, surgery duration, post-operative haemoglobin level and transfusion requirement were reviewed.
  
  
  RESULTS
  Overall transfusion rate was 10.6% (n=24). Cross-match to transfusion ratio was 6.5. The cross-match to transfusion ratio (C:T ratio) was measured as the ratio of number of units of blood cross-matched to units of blood transfused. In females, relative risk of transfusion between patients with pre-operative haemoglobin below 12.0 and those above or equal to 12.0 was significant at 4.53 (Confidence interval (CI) 2.16 to 9.53). The relative risk of transfusion between patients above 65 years of age compared to those below 65 years of age was 1.13 (CI 1.03 to 1.23). Multivariate analysis revealed advancing age (p=0.044) and lower preoperative haemoglobin (p<0.001) as significant variables associated with post-operative transfusion.
  
  
  CONCLUSIONS
  Post-operative transfusion rates are low and excessive pre-operative GXM and post-operative haemoglobin checks are contributing to unnecessary medical costs. Predictors of blood transfusion risk in unilateral TKA in our cohort of Asian population were advancing age and lower pre-operative haemoglobin level. Type and screen tests should be performed for all other patients. LEVEL OF SCIENTIFIC EVIDENCE: 3.
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hospital, Singapore. Electronic address: adrieltay91@gmail.com.
authors.forename: You Wei Adriel
authors.initials: YW
authors.lastname: Tay
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.
authors.forename: Yew Lok
authors.initials: YL
authors.lastname: Woo
authors.affiliation: Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.
authors.forename: Hwee Chye Andrew
authors.initials: HC
authors.lastname: Tan
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D016063:Blood Loss, Surgical / Q000517:prevention & control*; D001803:Blood Transfusion / Q000706:statistics & numerical data*; D001804:Blood Transfusion, Autologous / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D019106:Postoperative Hemorrhage / Q000517:prevention & control*; D057234:Preoperative Period; D011379:Prognosis; D012189:Retrospective Studies
keywords: Group cross-match; Haemoglobin; Healthcare resources; Total knee arthroplasty; Transfusion