Epidemiology
Acute appendicitis is one of the most common acute surgical abdominal emergencies.[4]Koepsell TD. In search of the cause of appendicitis. Epidemiology. 1991 Sep;2(5):319-21.
http://www.ncbi.nlm.nih.gov/pubmed/1742378?tool=bestpractice.com
More than 34,600 cases were treated in UK hospitals in 2006 to 2007. Most cases were in male subjects (30,120) and occurred predominantly in the 15 to 59 year age group. A large majority presented (29,576) as medical emergencies.[5]Health and Social Care Information Centre. Hospital episode statistics: England. March 2019 [internet publication].
https://digital.nhs.uk/data-and-information/data-tools-and-services/data-services/hospital-episode-statistics
More than 250,000 appendicectomies are performed each year in the US;[6]Owings MF, Kozak LJ. Ambulatory and inpatient procedures in the United States, 1996. Vital Health Stat 13. 1998;139:1-119.
http://www.cdc.gov/nchs/data/series/sr_13/sr13_139.pdf
http://www.ncbi.nlm.nih.gov/pubmed/9866429?tool=bestpractice.com
however, the incidence is lower in populations where a high-fibre diet is consumed.[7]Arnbjornsson E. Acute appendicitis and dietary fiber. Arch Surg. 1983 Jul;118(7):868-70.
http://www.ncbi.nlm.nih.gov/pubmed/6305309?tool=bestpractice.com
The overall lifetime risk of developing acute appendicitis is 8.6% for males and 6.7% for females; lifetime risk of appendicectomy is around 12% in males and 23% in females.[8]Körner H, Söndenaa K, Söreide JA, et al. Incidence of nonperforated and perforated appendicitis: age-specific and sex-specific analysis. World J Surg. 1997 Mar-Apr;21(3):313-7.
http://www.ncbi.nlm.nih.gov/pubmed/9015177?tool=bestpractice.com
[9]Addiss DG, Shaffer N, Fowler BS, et al. The epidemiology of appendicitis and appendectomy in the United States. Am J Epidemiol. 1990 Nov;132(5):910-25.
http://www.ncbi.nlm.nih.gov/pubmed/2239906?tool=bestpractice.com
The rate of appendicectomy is around 10 per 10,000 cases per year in the US.[10]Flum DR, Koepsell TD. The clinical and economic correlates of misdiagnosed appendicitis: nationwide analysis. Arch Surg. 2002 Jul;137(7):799-804.
https://jamanetwork.com/journals/jamasurgery/fullarticle/212659
http://www.ncbi.nlm.nih.gov/pubmed/12093335?tool=bestpractice.com
This condition is most commonly seen in patients aged between early teens and late 40s. There is a slight male to female predominance (1.3:1).
Risk factors
Known to cause constipation. Patients with appendicectomies have low fibre in their diet compared with controls.[7]Arnbjornsson E. Acute appendicitis and dietary fiber. Arch Surg. 1983 Jul;118(7):868-70.
http://www.ncbi.nlm.nih.gov/pubmed/6305309?tool=bestpractice.com
However, the theory that this is associated with a higher risk of appendicitis is controversial.[14]Naaeder SB, Archampong EQ. Acute appendicitis and dietary fibre intake. West Afr J Med. 1998 Oct-Dec;17(4):264-7.
http://www.ncbi.nlm.nih.gov/pubmed/9921094?tool=bestpractice.com
A higher incidence of acute appendicitis in Western society may be related to the living conditions and improved personal hygiene.[15]Barker DJ, Osmond C, Golding J, et al. Acute appendicitis and bathrooms in three samples of British children. Br Med J (Clin Res Ed). 1988 Apr 2;296(6627):956-8.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2545433/
http://www.ncbi.nlm.nih.gov/pubmed/3129107?tool=bestpractice.com
A balance of gastrointestinal microbial flora is important for prevention of infection, for digestion, and for providing important nutrients.[16]Huis in 't Veld JH. Gastrointestinal flora and health in man and animal [in Dutch]. Tijdschr Diergeneeskd. 1991 Mar 1;116(5):232-9.
http://www.ncbi.nlm.nih.gov/pubmed/1901673?tool=bestpractice.com
Frequent use of antibiotics and improved hygienic conditions lead to decreased exposure and/or imbalance of gastrointestinal microbial flora that may eventually lead to a modified response to viral infection and thereby trigger appendicitis.[17]Walker AR, Segal I. What causes appendicitis? J Clin Gastroenterol. 1990 Apr;12(2):127-9.
http://www.ncbi.nlm.nih.gov/pubmed/2157745?tool=bestpractice.com
There is an increased incidence of acute appendicitis in adult patients who smoke every day compared with adults who never smoked.[18]Montgomery SM, Pounder RE, Wakefield AJ. Smoking in adults and passive smoking in children are associated with acute appendicitis. Lancet. 1999 Jan 30;353(9150):379.
http://www.ncbi.nlm.nih.gov/pubmed/9950450?tool=bestpractice.com