Temporal trends in transfusion among US hospitalizations between 2015Q4 and 2018Q4. The line graphs represent the proportion of discharges transfused with a given blood component per quarter year. The data represent weighted estimates for ∼10 million weighted discharges per quarter in the National Inpatient Sample (2015Q4-2018). The P_trend values shown were calculated by log binomial regression. For 2015, only data from Q4 were included because of the transition to ICD-10 coding scheme from that time point.