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Negative Appendectomy and Imaging Accuracy in the Washington State Surgical Care and Outcomes Assessment Program

Florence, Michael MD; Flum, David R. MD, MPH*‡; Jurkovich, Gregory J. MD*; Lin, Paul MD§; Steele, Scott R. MD; Symons, Rebecca Gaston MPH*‡; Thirlby, Richard MDThe SCOAP Collaborative. The SCOAP Collaborative included Joseph Cuschieri MD

doi: 10.1097/SLA.0b013e318187aeca
Original Articles

Objective: To evaluate negative appendectomy (NA) and the relationship of NA and computed tomography (CT) and/or ultrasound (US).

Summary Background Information: NA may be influenced by the use and accuracy of preoperative CT/US. The Surgical Care and Outcomes Assessment Program (SCOAP) gathers chart-abstracted process of care data (such as CT/US accuracy) for general surgical procedures (including appendectomy) at most Washington State hospitals.

Methods: We determined the prevalence of NA and CT/US concordance at the 15 SCOAP hospitals with >50 consecutive patients undergoing appendectomy (2006–2007).

Results: The number of patients who underwent urgent appendectomies was 3540. The percentage of patients who had imaging (CT-91%) was 86% (women-89%, men-83%). The use of imaging ranged across hospitals from 56% to 97%. There was 91% agreement between imaging and pathology report findings (92.3%-CT and 82.4%-US). The overall rate of NA was 6% (women-8%, men-4%). The prevalence of NA was 9.8% among patients having no imaging, 8.1% among those having an US, and 4.5% in those having a CT. Among patients with NA, CT/US was obtained in 75%; correct in 10% and incorrect or ambiguous in 65%. Higher rates of NA were correlated with lower rates of CT/US concordance (r = −0.57). There was no significant difference in rates of perforation between those with (17%) and without (15%) imaging (P = 0.2). There were significant increases in the use of CT/US and decreases in NA over the time period (P < 0.01).

Conclusions: The prevalence of NA at SCOAP hospitals decreased significantly. Variation in NA between hospitals was linked closely to CT/US accuracy suggesting CT/US accuracy should be considered a measure of quality in the care of patients with presumed appendicitis.

The Surgical Care and Outcomes Assessment Program gathers prospective, chart-abstracted data for consecutive operative procedures at Washington State hospitals. Through the Surgical Care and Outcomes Assessment Program, rates of negative appendectomy and computed tomography/ultrasound concordance with pathology reports were calculated for 2006 to 2007 across 16 statewide hospitals to determine rates of negative appendectomy and the relationship of negative appendectomy and computed tomography/ultrasound, which have been found to influence negative appendectomy.

From the *Department of Surgery, University of Washington, †Swedish Medical Center, ‡Department of the Surgical Outcomes Research Center, University of Washington, Seattle; §Sacred Heart Medical Center, Spokane; ¶Madigan Army Medical Center, Tacoma; and ∥Virginia Mason Medical Center, Health Sciences Center, Seattle, WA.

Supported by the Foundation for Healthcare Quality and Washington State's Life Science Discovery Fund.

Reprints: David R. Flum, MD, MPH, Department of Surgery, University of Washington, Health Sciences Center, Box 356410, Seattle WA 98195-7183. E-mail:

© 2008 Lippincott Williams & Wilkins, Inc.