Yoeri Bemelmans

Chapter 3 36 Statistics All statistical analyses were performed with the use of Statistical Package for the Social Sciences version 26.0 for windows (SPSS., Inc., Chicago, IL). Descriptive statistics are used to summarize data. Student’s t-tests were performed on significant interactions between both groups. Chi-square test was used for categorical variables. A threshold for all statistical comparisons of p-value ≤0.05was considered to be statistically significant. Data are presented as means with standard deviations, 95% confidence level (CI), frequencies (%) or medians with ranges. Results A total group of 5205 patients were analysed. The incidence of perioperative blood transfusionwas 0.94%(n=49). One patient (TKA) received blood transfusion during the operation, as the other patients received blood transfusion after surgery on the clinical ward. Study patients were divided into two groups, transfused- (BT) and non-transfused (non-BT) patients. Differences for patient demographics and perioperative outcome measures between BT and non-BT patients are presented in table 1. Patients in the BT group had significant (P≤0.05) higher ASA score (≥III), age, prolonged LoS, and lower BMI scores. No significant differences were found for type of anesthesia and side of surgery. Only in THA patients, the BT group had a longer duration of surgery, higher estimated blood loss and consisted of significantly more uncemented arthroplasties. Pre- and postoperative Hb levels in THA and TKA patients were statistically significant different between BT and non-BT patients. Since there were no transfusions in the UKA group; estimated blood loss, duration of surgery and perioperative Hb levels could not be sub-analysed. AE’s and readmission rates are presented in table 2 for both groups with an incidence of 0.46% for thromboembolic AE’s (e.g. deep vein thrombosis/lung embolism/cerebrovascular- or myocardial event).