Epidemiologic Features of Appendicitis

Though appendicitis is common many important questions remain unanswered. When is the appendix normal and when is it the cause of abdominal pain? Why does appendicitis primarily affect older children and young adults? Why is appendicitis uncommon in those under five years of age and in those over sixty years of age? Why are boys affected more often than girls? Why does appendicitis appear to run in some families? Why is appendicitis more common in affluent parts of the world and rare in parts where poverty and poor hygiene are prevalent? The epidemiology of appendicitis is complex and its cause is not explained by any single factor. The peak incidence of appendicitis coincides with the age when the immune system is most efficient and the lymphoid follicles are at their maximum development. Could this implicate immunological factors in the pathogenesis and, therefore, the epidemiology of appendicitis? Obstruction of the lumen of the appendix is believed to be the trigger initiating the processes that culminate in inflammation of the appendix. Fecaliths are a specific cause of appendicitis in about one-third of specimens (Mitros & Rubin, 2009) and are composed of fats (coprosterols), inorganic salts (calcium phosphate) and organic residue (vegetable fibres) in a proportion of 50%, 25% and 20%, respectively (Berg, RM., & Berg, HM., 1957). Their physical consistency varies from soft to hard concretions. The reported incidence of fecaliths depends on whether the data was obtained from intraoperative palpation of the organ, from histological analysis of operative specimens or from autopsy reports. It is suggested that vegetable matter entering the lumen of the appendix forms the nucleus around which glandular secretions in the lumen desicate to form the calculi (Lowenberg, 1949). In the other two-thirds of instances where fecaliths are absent, the obstruction is thought to be caused by hypertrophy of mural lymphoid follicles in response to a host of causes that are discussed elsewhere in this book. This chapter aims to understand the environmental, demographic, cultural and genetic factors that make the appendix susceptible to obstruction and inflammation. To understand the epidemiology of appendicitis is to look at the possibility of moving beyond treating it operatively to entertaining non-operative treatments and to foresee a future when some cases of appendicitis can be prevented.