Andrzejewski, Chester

Abstract Background and objective: Blood loss associated with total lower-extremity joint arthroplasty (TJA) often results in postoperative anemia and need for red blood cell transfusions (RBCT). We report the results of a quality improvement initiative to improve blood management and decrease transfusions in patients undergoing TJA in one tertiary hospital. Methods: Pre and post analysis after the implementation of a multifaceted intervention which included preoperative assessment for anemia, use of tranexamic acid, discouragement of autologous pre-operative blood collection and institution of more restrictive RBCT protocols. The results were stratified into three periods: I - pre-interventional (01/01/2013 -09/30/2013); II - peri-interventional (10/01/2013 -04/30/2014); and III - post-interventional (05/01/2014 -12/31/2014). We used fractional logistic regression with robust standard errors and regression modeling was configured using a segmented, or "piecewise", approach in which slope coefficients in each period were estimated. Results: During the study period 2511 patients underwent surgery. Compared with the pre-intervention period, the total number of RBC units transfused decreased from a total of 587 in the pre- to 107 in the post-intervention period (81.8% decrease). The percentage of patients receiving transfusion declined from 36.7% in pre-implementation period to 8.8% to post-intervention period. Depending upon the costing methodology used, annualized savings in RBC expenditure between time period 1 and 3 ranged from a low of $108,000 using the acquisition cost per unit (~$225/unit) to $480,000 when using activity based costing (~$1000/unit). Mean length of stay (days) and 30-day readmission rates remained stable during the study period. Conclusions: A multidisciplinary approach with proactive involvement of all the interested parties can be successful and sustainable in reducing RBCT and its associated costs, in patients undergoing TJA. Disclosures No relevant conflicts of interest to declare.

Severe aplastic anemia (AA) is a bone marrow (BM) failure (BMF) disease frequently caused by aberrant immune destruction of blood progenitors. Although a Th1-mediated pathology is well described for AA, molecular mechanisms driving disease progression remain ill defined. The NOTCH signaling pathway mediates Th1 cell differentiation in the presence of polarizing cytokines, an action requiring enzymatic processing of NOTCH receptors by γ-secretase. Using a mouse model of AA, we demonstrate that expression of both intracellular NOTCH1IC and T-BET, a key transcription factor regulating Th1 cell differentiation, was increased in spleen and BM-infiltrating T cells during active disease. Conditionally deleting Notch1 or administering γ-secretase inhibitors (GSIs) in vivo attenuated disease and rescued mice from lethal BMF. In peripheral T cells from patients with untreated AA, NOTCH1IC was significantly elevated and bound to the TBX21 promoter, showing NOTCH1 directly regulates the gene encoding T-BET. Treating patient cells with GSIs in vitro lowered NOTCH1IC levels, decreased NOTCH1 detectable at the TBX21 promoter, and decreased T-BET expression, indicating that NOTCH1 signaling is responsive to GSIs during active disease. Collectively, these results identify NOTCH signaling as a primary driver of Th1-mediated pathogenesis in AA and may represent a novel target for therapeutic intervention.