Fig. 1.

Study cohort flow diagram for service-specific cohorts. Veterans with history of arrhythmia, coronary artery disease, valvular disease, heart failure, or a cardiology visit within 1 year prior to their surgery date or who had an EKG as part of an inpatient stay or ED visit within 30 days prior to their surgery date were excluded from the low-value preoperative EKG cohort. Veterans with history of valvular disease, heart failure, chronic obstructive pulmonary disease, asthma, other interstitial lung disease, or a pulmonary visit within one year prior to their surgery date or history of acute respiratory illness within 60 days prior to their surgery date or who had a CXR as part of an inpatient stay or ED visit within 30 days prior to their surgery date were excluded from the low-value CXR cohort. EKG = electrocardiogram; CXR – chest radiograph