The purpose of this cross-sectional study was to measure imaging utilization rates and the negative appendectomy rate (NAR) in metropolitan Seoul, Korea. The study included 2321 adolescents and adults (> or =15 yr; median [interquartile range] age, 37 [27-50] yr; 46.7% female) undergoing appendectomy in 2011 at eight tertiary and three secondary hospitals. Imaging utilization rate was 99.7% (95% confidence interval, 99.4%-99.9%). CT and ultrasonography utilization rates as an initial imaging modality were 93.1% (92.0%-94.1%), and 6.5% (5.6%-7.6%), respectively. The NAR in patients undergoing CT only, complementary ultrasonography following CT, ultrasonography only, and complementary CT following ultrasonography were 3.3% (2.6%-4.1%), 27% (14%-44%), 9% (4%-16%), and 8% (2%-20%), respectively. The use of ultrasonography instead of CT as the initial imaging modality was significantly associated with higher NAR (adjusted odds ratio [AOR], 2.28 [1.22-4.27]; risk difference, 4.4 [0-8.8] percentage points), however, the population attributable risk was 0.3 [0-0.6] percentage points. We observed a very high CT utilization rate and a low NAR in metropolitan Seoul. Although the use of CT was significantly associated with the lower NAR, CT utilization rate already has reached the level that increase in CT utilization from the status quo would hardly decrease the NAR further.
Acute Disease ; Adolescent ; Adult ; Appendicitis/*diagnosis/radiography/ultrasonography ; Cross-Sectional Studies ; Diagnostic Imaging/instrumentation/*utilization ; Female ; Humans ; Male ; Middle Aged ; Sensitivity and Specificity ; Tomography, X-Ray Computed ; Young Adult