Background: Addis et al.  described the epidemiology of appendicitis in the United States from 1970 to 1984. He reported that while overall incidence decreased, the highest incidence of appendicitis occurred in 10- to 19-y-olds. This study examines if the incidence of appendicitis and mean age of diagnosis has changed, and whether demographics are related to the frequency of admissions and incidence rate of acute appendicitis (AA).
Materials and methods: Study questions were assessed using the Nationwide Inpatient Sample (NIS) discharge data and US Census data from 1993-2008. Operatively managed, uncomplicated, and complex cases of AA were included. Incidental appendectomy and right hemicolectomy were excluded. Descriptive, ANOVA, χ(2), and test of proportion statistics were used to evaluate frequency of admissions, incidence rate, and demographic changes in appendicitis.
Results: The annual rate of AA increased from 7.62 to 9.38 per 10,000 between 1993 and 2008. The highest frequency of AA was found in the 10-19 y age group, however occurrence in this group decreased by 4.6%. Persons between ages 30 and 69 y old experienced an increase of AA by 6.3%. AA rates remained higher in males. Hispanics, Asians, and Native Americans saw a rise in the frequency of AA, while the frequencies among Whites and Blacks decreased.
Conclusions: While AA is most common in persons 10- to 19-y old, the mean age at diagnosis has increased over time. Minorities are experiencing an increase in the frequency of appendicitis. The changing demographics of the US plays a role in the current epidemiology of appendicitis, but is not solely responsible for the change observed.
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