Time to appendectomy and risk of perforation in acute appendicitis

In the traditional model of acute appendicitis, time is the major driver of disease progression; luminal obstruction leads inexorably to perforation without timely intervention. This perceived association has long guided clinical behavior related to the timing of appendectomy.

To evaluate whether there is an association between time and perforation after patients present to the hospital.

Using data from the Washington State Surgical Care and Outcomes Assessment Program (SCOAP), we evaluated patterns of perforation among patients (≥18 years) who underwent appendectomy from January 1, 2010, to December 31, 2011. Patients were treated at 52 diverse hospitals including urban tertiary centers, a university hospital, small community and rural hospitals, and hospitals within multi-institutional organizations.

The main outcome of interest was perforation as diagnosed on final pathology reports. The main predictor of interest was elapsed time as measured between presentation to the hospital and operating room (OR) start time. The relationship between in-hospital time and perforation was adjusted for potential confounding using multivariate logistic regression. Additional predictors of interest included sex, age, number of comorbid conditions, race and/or ethnicity, insurance status, and hospital characteristics such as community type and appendectomy volume.

A total of 9048 adults underwent appendectomy (15.8% perforated). Mean time from presentation to OR was the same (8.6 hours) for patients with perforated and nonperforated appendicitis. In multivariate analysis, increasing time to OR was not a predictor of perforation, either as a continuous variable (odds ratio =  1.0 [95% CI, 0.99-1.01]) or when considered as a categorical variable (patients ordered by elapsed time and divided into deciles). Factors associated with perforation were male sex, increasing age, 3 or more comorbid conditions, and lack of insurance.

There was no association between perforation and in-hospital time prior to surgery among adults treated with appendectomy. These findings may reflect selection of those at higher risk of perforation for earlier intervention or the effect of antibiotics begun at diagnosis but they are also consistent with the hypothesis that perforation is most often a prehospital occurrence and/or not strictly a time-dependent phenomenon. These findings may also guide decisions regarding personnel and resource allocation when considering timing of nonelective appendectomy.