TY - JOUR
T1 - Ultrasound evaluation of appendicitis
T2 - Importance of the 3 × 2 table for outcome reporting
AU - Fedko, Martin
AU - Bellamkonda, Venkatesh R.
AU - Bellolio, M. Fernanda
AU - Hess, Erik P.
AU - Lohse, Christine M.
AU - Laack, Torrey A.
AU - Laughlin, Michael J.
AU - Campbell, Ronna L.
PY - 2014/4
Y1 - 2014/4
N2 - Introduction Despite a relatively high frequency of appendix nonvisualization when using ultrasound to diagnose appendicitis, many studies either fail to report these results or inconsistently analyze outcomes. Objectives The objective of this study is to determine the most transparent and accurate way of reporting and analyzing ultrasound results for the diagnosis of appendicitis. Methods This was an observational cohort study of emergency department patients age 18 years or older who underwent right lower quadrant ultrasonography from September 2010 to October 2011. Patient characteristics, imaging, pathology, and follow-up data were analyzed. Test characteristics were calculated using conventional 2 × 2 contingency table analysis excluding inconclusive ultrasound results and an intention-to-diagnose approach with a 3 × 2 table. Results Sixty-five patients were included. Forty-four (68%) patients had a nonvisualized appendix resulting in an overall diagnostic yield of 32%. Twenty-one patients had a visualized appendix (14 [22%] negative and 7 [11%] positive for appendicitis). Using 2 × 2 contingency table analysis, sensitivity and specificity were 100%. Using the 3 × 2 table with and the intention-to-diagnose principle, sensitivity was 70% and specificity was 25%. Three (7%) of 44 patients with a nonvisualized appendix had appendicitis (likelihood ratio = 0.40). Discussion We suggest reporting ultrasound results using a 3 × 2 table (including nonvisualized findings) but using the traditional 2 × 2 type of analysis for test characteristic calculations. This approach allows for the determination of diagnostic yield and calculation of likelihood ratios when the appendix is not visualized. This approach to reporting should be considered for all types of diagnostic ultrasound studies.
AB - Introduction Despite a relatively high frequency of appendix nonvisualization when using ultrasound to diagnose appendicitis, many studies either fail to report these results or inconsistently analyze outcomes. Objectives The objective of this study is to determine the most transparent and accurate way of reporting and analyzing ultrasound results for the diagnosis of appendicitis. Methods This was an observational cohort study of emergency department patients age 18 years or older who underwent right lower quadrant ultrasonography from September 2010 to October 2011. Patient characteristics, imaging, pathology, and follow-up data were analyzed. Test characteristics were calculated using conventional 2 × 2 contingency table analysis excluding inconclusive ultrasound results and an intention-to-diagnose approach with a 3 × 2 table. Results Sixty-five patients were included. Forty-four (68%) patients had a nonvisualized appendix resulting in an overall diagnostic yield of 32%. Twenty-one patients had a visualized appendix (14 [22%] negative and 7 [11%] positive for appendicitis). Using 2 × 2 contingency table analysis, sensitivity and specificity were 100%. Using the 3 × 2 table with and the intention-to-diagnose principle, sensitivity was 70% and specificity was 25%. Three (7%) of 44 patients with a nonvisualized appendix had appendicitis (likelihood ratio = 0.40). Discussion We suggest reporting ultrasound results using a 3 × 2 table (including nonvisualized findings) but using the traditional 2 × 2 type of analysis for test characteristic calculations. This approach allows for the determination of diagnostic yield and calculation of likelihood ratios when the appendix is not visualized. This approach to reporting should be considered for all types of diagnostic ultrasound studies.
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U2 - 10.1016/j.ajem.2013.12.052
DO - 10.1016/j.ajem.2013.12.052
M3 - Article
C2 - 24512887
AN - SCOPUS:84898598587
SN - 0735-6757
VL - 32
SP - 346
EP - 348
JO - American Journal of Emergency Medicine
JF - American Journal of Emergency Medicine
IS - 4
ER -