Purpose The objectives of this study were 2-fold: 1) To identify patient characteristics associated with utilization of computed tomography (CT) and ultrasound (US) in the diagnosis of pediatric appendicitis, and 2) To calculate and compare standardized imaging rates between Children's Hospitals following adjustment for characteristics associated with increased utilization.
Methods We performed a retrospective audit of the Pediatric Health Information System database (1/2009-9/2011) to identify all patients diagnosed with acute appendicitis who underwent appendectomy during the same admission at 40 Children's Hospitals. Hierarchical multivariable regression using General Estimating Equations to adjust for clustering was used to examine the influence of age, gender, race, insurance status, median household income and the presence of chronic medical conditions on CT and US utilization. Standardized imaging rates were calculated and compared between hospitals with utilization outliers defined as those whose rate and 95% Confidence Intervals (CI) did not include the overall mean rate.
Results 28,038 patients were identified (hospital median:631, range:179-2,107). Characteristics associated with (or a strong trend toward) increased imaging utilization (CT or US) included Hispanic race (Hispanic vs. White:OR 1.51[95%CI:1.29-1.78]), female gender (OR 1.25[95%CI:1.16-1.34]), chronic medical conditions (OR 1.19[95%CI:1.03-1.37]), and very young and adolescent age groups (3-7y vs. 8-12y:OR 1.08[95%CI:0.99-1.18]; 13-18y vs. 8-12y:OR 1.11[95%CI:1.02-1.20]). Following standardization, a 3.2-fold variation in the rate of any imaging was observed across hospitals (overall rate:50.8%; range:23.2%-75.2%;p<0.0001) with sub-group analysis revealing a 33.5-fold variation in the rate of CT scanning (overall rate:23.7%; range:1.7%-57.9%;p<0.0001;figure), a 67-fold variation in US utilization (overall rate:31.8%; range:0%-67.5%;p<0.0001;figure), and a 15-fold variation in the rate of patients receiving both imaging modalities (overall rate:5.8%; range:0%-14.8%;p<0.0001). When compared to the overall standardized rate from the entire cohort, 30%(12/40) of hospitals were found to have significantly higher imaging rates (either CT or US) and 25%(10/40) had significantly lower rates. Further sub-group analysis demonstrated that 35%(14/40) of hospitals had significantly higher rates of CT utilization relative to the group while 35%(14/40) of hospitals had lower rates. Similarly, 35%(14/40) of hospitals had significantly higher rates of US utilization while 50%(20/40) of hospitals had lower rates (figure). Twenty-five percent (10/40) of hospitals had significantly higher rates of redundant imaging (both CT and US), while 43%(17/40) of hospitals had lower rates. There was a strong inverse correlation between the use of CT and US across hospitals (Spearman's r=-0.711;p<0.0001;figure), and no correlation was found between hospital volume and imaging rates for CT (r=-0.114;p=0.80), US (r=0.035;p=0.83), or the use of any imaging modality (r=-0.114;p=0.49).
Conclusion Significant variation exists among Children's Hospitals in the use of diagnostic imaging for appendicitis. Establishment of a collaborative quality improvement platform through which imaging protocols can be shared and prospectively audited against relevant outcomes may provide an effective strategy for reducing resource utilization and radiation exposure associated with pediatric appendicitis.