Differential impact of transfusion guidelines on blood transfusion practices within a health network.

Whether clinical practice guidelines have a significant impact on practice is unclear. The effect of guideline recommendations on clinical practice often a lags behind the date of publication. We evaluated by means of a data-driven approach if and when the guidelines on red blood cell transfusions (RBCTs) issued by Swiss Smarter Medicine in 2016 had an impact on RBCTs practice within a hospital network, where awareness of guidelines was promoted mainly among internal medicine specialties. Data on RBCTs performed in a Swiss hospital network from January 2014 to April 2021 were analyzed by hospital site and specialty to assess whether guidelines led to a decrease in inappropriate RBCTs. RBCTs were defined as "inappropriate" if patients had a hemoglobin level ≥ 70 g/L without or ≥ 80 g/L with significant cardiovascular comorbidities. Changes in the rate of inappropriate transfusions were analyzed with an advanced statistical approach that included generalized additive models. Overall prior to March 2017 there were more inappropriate than appropriate RBCTs, but after October 2017 the opposite could be observed. A change-point in the time trend was estimated from transfusion data to occur in the time interval between March and October 2017. This change was mainly driven by practice changes in the medical wards, while no significant change was observed in the critical care, surgical and oncology wards. Change in practice varied by hospital site. In conclusion, our results show that a significant change in the RBCTs practice at the hospital level occurred approximately 18 months after national guidelines were issued.