The clinical and economic correlates of misdiagnosed appendicitis: nationwide analysis.

BACKGROUND Negative appendectomy (NA)--the nonincidental removal of a normal appendix--occurs commonly but the associated clinical- and system-level costs are not well studied. HYPOTHESIS The frequency of adverse clinical outcomes and associated financial burden of hospitalizations during which NA is performed is greater than previously recognized and varies widely among demographic groups. DESIGN Population-based, retrospective cohort study. SETTING The 1997 Nationwide Inpatient Sample of the Health Care Utilization Project. PATIENTS All surveyed patients assigned International Classification of Diseases, Ninth Revision procedure codes for appendectomy but without an associated diagnosis of acute appendicitis. MAIN OUTCOME MEASURES The age- and sex-stratified rates of NA, the incidence of associated infectious complications and case fatality, and the average length of stay and hospitalization charges during those admissions. RESULTS Nationwide, an estimated 261 134 patients underwent nonincidental appendectomies in 1997, and 39 901 (15.3%) were negative for appendicitis. Women had a higher rate of NA as did patients younger than 5 years and older than 60 years. When compared with patients with appendicitis, NA was associated with a significantly longer length of stay (5.8 vs 3.6 days, P<.001), total charge-admission ($18 780 vs $10 584, P<.001), case fatality rate (1.5% vs 0.2%, P<.001), and rate of infectious complications (2.6% vs 1.8%, P<.001). An estimated $741.5 million in total hospital charges resulted from admissions in which a NA was performed. CONCLUSIONS There are significant clinical and financial costs incurred by patients undergoing NA during the treatment of presumed appendicitis. These should be considered when evaluating system-level interventions to improve the management of appendicitis.