Association for Academic SurgeryChanging Epidemiology of Acute Appendicitis in the United States: Study Period 1993–2008
Introduction
Acute appendicitis (AA) is the one of the most common abdominal emergencies found in the United States. Approximately 11 in 10,000 people will experience appendicitis in their lifetime [1]. This rapidly progressing inflammatory process requires prompt removal of the appendix to prevent life-threatening complications such as ruptured appendix and peritonitis [1]. The epidemiology of this condition has been revisited multiple times throughout the world, with most studies agreeing that the most likely age group affected is between the ages of 10 and 19 y. Additionally, a common trend seems to be that appendicitis rates are decreasing.
European studies indicate a trend in decreasing rate of appendicitis in young adults, ages 10 to 19 y old. Recently, a Danish study showed a decrease in incidence of uncomplicated appendicitis in the same age range. Between the years 1996 and 2004, there was a 27.8% decrease in AA in males ages 10 to 14 y, and 12.8% decrease in males ages 15 to 19 y. This trend was similar in the female population with a 35.9% decrease in AA in ages 10 to 14 y and a 22.5% decrease in ages 15 to 19 y [2]. Similarly, this trend in decreased incidence was shown through a retrospective review in a small Spanish community during a 10-y study from 1998 to 2007. Frequency of appendectomy in this community displayed a slight descending trend. The female population showed the greatest decrease in AA diagnosis [3].
Studies in North America indicate a similar trend in decreasing rate of appendicitis. An overall 5.1% decrease in annual rate of AA between the years 1991 and 1998 was reported by Al-Omran et al. in a Canadian study. In females, the decrease was 3.1% and in males it was 6.5%. The incidence was highest in males and females aged 10 to 19 y, and the frequency of AA declined with age increment [4]. In the United States, a study on the epidemiology of appendicitis showed a decreasing trend from 1970 through 1984. Addis et al. analyzed data from the National Hospital Discharge Survey (NHDS), and similar to his international counterparts, he found that while the overall incidence decreased by 14.6%, the highest incidence of appendicitis remained in ages 10 to 19 y [5].
At our community teaching hospital, we have observed a trend of older persons, >age 40 y, presenting with appendicitis and wondered whether this trend was occurring on a national level. Data from the United States Census Bureau shows that the population profile in the United States is changing. The mean age has risen to between 30 and 40 for most ethnicities, and additionally the racial profile is becoming more diverse [6]. We hypothesize that the changing demographics of the United States has played a role in changing the epidemiology of appendicitis. In our study, we examine the epidemiology of appendicitis using a nationwide database, looking at possible trends during the period of 1993 to 2008. Our study examines if there has been a shift in the mean age of diagnosis, and if gender and race are still related to the incidence of this disease process.
Section snippets
Materials and Methods
Data were extracted from the National Inpatient Sample (NIS), a national database available from the Healthcare Cost Utilization Project (HCUP), which is sponsored by the Agency for Healthcare Research and Quality (AHRQ) [7]. The NIS database contains information on inpatient hospital stays from about 1000 hospitals in 22 states from 1988 through 2008. For our study, we used data from 1993 through 2008 because of sampling design modifications that took effect in 1993. NIS discharge weights were
National Trend
The annual rate (per 10,000 population) of all AA increased from 7.62 in 1993 to 9.38 in 2008 (Fig. 1). From 1993 to 1998, the annual rate remained stable at approximately 7.7 cases per 10,000. There has been gradual increase with peak in 2005 at about 9.7 cases per 10,000 and since remained stable at about 9.4 cases per 10,000.
US Demographic Characteristics
A total of 3,913,030 weighted cases met our inclusion criteria in the NIS data set from 1993 through 2008. Table 1 shows characteristics of appendicitis patients at
Discussion
The incidence of AA increased from 7.62 per 10,000 in 1993 to 9.38 per 10,000 in 2008. This finding is contrary to our initial hypothesis that the incidence of appendicitis is decreasing. As reported by Addis et al., the incidence of appendicitis was decreasing in the United States between the years 1970 and 1984 [5]. Some of the rise in cases of appendicitis may be attributable to population growth and the changing demographics of the Untied States. However, our study shows that the rise in
Conclusion
The incidence of AA is increasing in the United States. Changing demographics are a reason, but not the sole reason, for the increased frequency of hospital admissions due to AA in certain regions and types of hospitals. Changes in racial profiles contribute to the current epidemiology of AA. The percent changes in diagnosis of AA across demographic groups may also result from improved technology, better access to health care, and longer life span.
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