Abstract
Background
International Classification of Disease, ninth/tenth revision codes are used to identify
patients with appendicitis and classify severity of disease for research and hospital
reimbursement. We sought to determine accuracy of International Classification of
Disease, ninth/tenth revision codes in classifying appendicitis as uncomplicated versus
complicated (defined as perforated, necrotic, or abscess) compared with the clinical
gold standard: surgeon characterization of the appendix in the operative report.
Methods
Retrospective review of operative reports and discharge International Classification
of Disease, ninth/tenth revision codes for patients ≥18 years old who underwent noninterval,
nonincidental appendectomy between January 2012 and December 2019 at a tertiary referral
center. Sensitivity, specificity, and positive predictive value were calculated for
International Classification of Disease, ninth/tenth revision codes to classify appendicitis
accurately as complicated compared with surgeon description. ICD-9/10 codes and surgeon
description were categorized into complicated/uncomplicated based on the American
Association for the Surgery of Trauma grading system.
Results
In the study, 1,495 patients with acute appendicitis underwent appendectomy. Per surgeon
description, 200 (13%) were complicated and 1,295 (87%) uncomplicated. Compared with
surgeon description, discharge International Classification of Disease, ninth/tenth
revision codes did not accurately identify complicated appendicitis: sensitivity =
0.68, positive predictive value = 0.77. As a sensitivity analysis, the cohort was
stratified by public versus private payers, and the results did not change.
Conclusion
International Classification of Disease, ninth/tenth revision codes do not accurately
identify surgeon-described complicated appendicitis. Nearly one-third of the cases
of complicated appendicitis were coded as uncomplicated. Such misclassification negatively
impacts reimbursement for complicated appendicitis care and could lead to misleading
results in research and quality improvement activities that rely on these codes.
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Article info
Publication history
Published online: August 16, 2022
Accepted:
June 13,
2022
Identification
Copyright
© 2022 Elsevier Inc. All rights reserved.
