BACKGROUND: CT and ultrasound (US) are increasingly recommended to establish the diagnosis of appendicitis, but population-based rates of misdiagnosis (negative appendectomy [NA]) have not improved over time. The objective of this study was to determine the relationship between CT/US and NA in common practice. STUDY DESIGN: Using data from the Group Health Cooperative on all patients undergoing appendectomy between 1980 and 1999, a longitudinal study was conducted to determine the frequency of NA over time and a case-control, medical record-based study of a subset of patients from the 1990s was conducted to determine the accuracy of CT/US. RESULTS: Of 4,058 patients undergoing appendectomy (mean age 31 +/- 18.6 [SD] years, 49.6% women), 631 (15.5%) had an NA. The overall incidence of NA remained stable over time at 1.5/10,000 patient-years, as did the age and gender adjusted rate (incident rate ratio 0.95, 95% CI 0.97, 1.01). In 1999, nearly 40% of patients had either CT or US. The aggregate sensitivity of these tests was only 74.2% (95% CI 65.7, 83.7), with a positive predictive value of 95.1% (95% CI 91.5, 96.8). CT scans were 88.3% sensitive, with 97.2% positive predictive value (95% CI 92.9, 100). Ultrasounds were 69.5% sensitive, with a positive predictive value of 94.1% (95% CI 89.6, 96.4). More than one in five tests obtained in patients with NA were positive for appendicitis (21.7% for CT and 20.8% for US). CONCLUSIONS: The rate of NA was unchanged over time despite the introduction and use of CT/US, and this appeared to be related to the inconsistent performance characteristics of the tests. This study cautions against overreliance on CT/US in diagnosing appendicitis and emphasizes the need for test benchmarking in routine practice before establishing protocols for presumed appendicitis.
BACKGROUND: CT and ultrasound (US) are increasingly recommended to establish the diagnosis of appendicitis, but population-based rates of misdiagnosis (negative appendectomy [NA]) have not improved over time. The objective of this study was to determine the relationship between CT/US and NA in common practice. STUDY DESIGN: Using data from the Group Health Cooperative on all patients undergoing appendectomy between 1980 and 1999, a longitudinal study was conducted to determine the frequency of NA over time and a case-control, medical record-based study of a subset of patients from the 1990s was conducted to determine the accuracy of CT/US. RESULTS: Of 4,058 patients undergoing appendectomy (mean age 31 +/- 18.6 [SD] years, 49.6% women), 631 (15.5%) had an NA. The overall incidence of NA remained stable over time at 1.5/10,000 patient-years, as did the age and gender adjusted rate (incident rate ratio 0.95, 95% CI 0.97, 1.01). In 1999, nearly 40% of patients had either CT or US. The aggregate sensitivity of these tests was only 74.2% (95% CI 65.7, 83.7), with a positive predictive value of 95.1% (95% CI 91.5, 96.8). CT scans were 88.3% sensitive, with 97.2% positive predictive value (95% CI 92.9, 100). Ultrasounds were 69.5% sensitive, with a positive predictive value of 94.1% (95% CI 89.6, 96.4). More than one in five tests obtained in patients with NA were positive for appendicitis (21.7% for CT and 20.8% for US). CONCLUSIONS: The rate of NA was unchanged over time despite the introduction and use of CT/US, and this appeared to be related to the inconsistent performance characteristics of the tests. This study cautions against overreliance on CT/US in diagnosing appendicitis and emphasizes the need for test benchmarking in routine practice before establishing protocols for presumed appendicitis.
Authors: Benjamin D Godwin; Frederick T Drake; Vlad V Simianu; Jabi E Shriki; Daniel S Hippe; Manjiri Dighe; Sarah Bastawrous; Carlos Cuevas; David Flum; Puneet Bhargava Journal: AJR Am J Roentgenol Date: 2015-06 Impact factor: 3.959
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Authors: Marjolein M N Leeuwenburgh; Sebastiaan Jensch; Jan W C Gratama; Aart Spilt; Bart M Wiarda; H Wouter Van Es; Lodewijk P J Cobben; Patrick M M Bossuyt; Marja A Boermeester; Jaap Stoker Journal: Eur Radiol Date: 2013-09-08 Impact factor: 5.315
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Authors: Anna Solberg; Lena Holmdahl; Peter Falk; Ingrid Palmgren; Marie-Louise Ivarsson Journal: Int J Colorectal Dis Date: 2008-03-18 Impact factor: 2.571