|Year : 2014 | Volume
| Issue : 4 | Page : 185-190
Epidemiology of appendicitis in Northern Nigeria: A 10-year review
Saad Aliyu Ahmed1, Jerry G Makama2, Umar Mohammed1, Robert B Sanda3, Sani Mohammed Shehu1, Emmanuel A Ameh2
1 Department of Pathology, Ahmadu Bello University Teaching Hospital Zaria, Nigeria
2 Department of Surgery, Ahmadu Bello University Teaching Hospital Zaria, Nigeria
3 Department of Pathology, Ahmadu Bello University Teaching Hospital Zaria, Nigeria; Department of Surgery, Drumheller Hospital, 351, 9th Street NW, Drumheller, Alberta, Canada
|Date of Submission||27-Feb-2014|
|Date of Acceptance||14-Sep-2014|
|Date of Web Publication||14-Nov-2014|
Saad Aliyu Ahmed
Department of Pathology, Ahmadu Bello University Teaching Hospital, Zaria, 810 001, Nigeria
Background: The true incidence rate of appendicitis in Nigeria and the magnitude of appendicular fecaliths as a specific causal factor in appendicitis are unknown. Materials and Methods: A retrospective clinicopathologic study was conducted using the medical database of the Ahmadu Bello University teaching hospital, Zaria, northern Nigeria for the decade from 2001 to 2010. The National Population Census in Nigeria 2006 was used to estimate the standardized annual incidence of appendicitis in the locality. Pathologically confirmed specimens of appendicitis were analyzed against demographic data of the patient. Results: During the decade, there were a total of 382 cases with intraoperative diagnosis of appendicitis of which the diagnosis was confirmed pathologically in 373 cases. With a local population whose disease or specimens would most probably end up in this hospital pathology department estimated at 1,423,469 the standardized incidence rate of appendicitis was 2.6 per 100,000 per annum. In 354 (93%) out of the 382 specimens, fecaliths were identified and thought to be causally related to the disease in the individual case. Conclusion: Appendicitis is very uncommon in northern Nigeria and when it occurs, it is almost always caused by fecaliths.
Keywords: Appendicitis, fecalith, Zaria
|How to cite this article:|
Ahmed SA, Makama JG, Mohammed U, Sanda RB, Shehu SM, Ameh EA. Epidemiology of appendicitis in Northern Nigeria: A 10-year review. Sub-Saharan Afr J Med 2014;1:185-90
|How to cite this URL:|
Ahmed SA, Makama JG, Mohammed U, Sanda RB, Shehu SM, Ameh EA. Epidemiology of appendicitis in Northern Nigeria: A 10-year review. Sub-Saharan Afr J Med [serial online] 2014 [cited 2019 Sep 21];1:185-90. Available from: http://www.ssajm.org/text.asp?2014/1/4/185/144729
| Introduction|| |
Appendicitis is generally thought to have a low incidence rate in sub-Saharan Africa and in other developing countries in Asia and Latin America. , One hypothesis holds that the high dietary fiber content of people in these parts of the world makes for a low fecal transit time and would account for a low incidence of fecaliths in the lumen of the appendix as a causal agent in people living in these parts of the world. ,, If true, this can only explain appendicitis in the estimated third of cases in which fecaliths are a specific cause of the disease but not in the majority where obstruction is not caused by fecaliths.  The only study that claimed to have correlated the incidence of fecaliths in the general population with the incidence of appendicitis was bedeviled by insensitive measure and sampling bias.  The claim and the conclusion in that study has been challenged by one of us.  A rival hypothesis holds that appendicitis is an immunological disease with a tendency to occur more frequently in communities with improvement in housing and public health indices. ,,,,, However, in a later study, it was found that a reduction in domestic overcrowding and a falling birth rate may have contributed to the epidemic after the Second World War.  This suggestion of overcrowding playing a beneficial role in the prevalence of appendicitis may suggest a role for poor hygiene in the low incidence of appendicitis in developing countries. It suggests that when individuals dwelling in these communities are exposed to local or remote infections the lymphoid follicles that abound in the wall of the appendix, hypertrophied to cause luminal obstruction. This hypothesis attempts to explain why appendicitis is more common in developed countries in comparison to developing countries.
The true incidence of appendicitis in developing countries like Nigeria is unknown due to poor medical record-keeping and unreliable population census. Estimates of population incidence of appendicitis in countries like Ghana,  Madagascar,  Central African Republic  and Ethiopia  have relied on small population counts but even then these figures show a low incidence in comparison to countries in Western Europe and North America.
There are no studies known to us from Nigeria that have estimated either the population incidence of appendicitis or the role of fecalith as a causal factor for acute appendicitis.
The Ahmadu Bello University Teaching Hospital in Zaria is the oldest and the most comprehensive medical institution in northern Nigeria. With surgical and pathology departments that have systematically maintained reliable records of operations and pathological specimens the authors are armed with a database that could provide a picture of appendicitis in this locality during the preceding decade. The 2006 national population census provided population counts by Local Government Areas. 
The study aimed to estimate the population incidence of appendicitis in Zaria Northern Nigeria and the role of fecaliths in pathological specimens in the disease.
| Materials and methods|| |
The study was designed as a retrospective clinico-pathological study covering the period from January 2001 to December 2010.
Ahmadu Bello University Teaching Hospital (ABUTH), Zaria, Nigeria with a 752-bed capacity, serves as the main referral hospital over a land area with a radius of over 100 km with a population in excess of 5 million. As an academic center, the teaching hospital has modeled itself to attain excellence in standards and its pathology department has no equal in the entire northern half of Nigeria.
Data was retrieved from operative and laboratory paper-based registers by searching for the keywords appendix and appendectomy. Further information was retrieved from patient records, specifically from the surgeon's operation notes and the histopathology report for all operations undertaken at the ABUTH during this period. Additional data were obtained from the medical records department pertaining to the total and monthly breakdown of outpatient department visits, admissions and specimens received in the histopathology department over the period of study.
Information retrieved for each case include the name of the patient, medical record number, age, gender place of domicile, preoperative diagnosis, hospital where operation was done (if not done at ABUTH), the date of the operation, the operative findings including incidental findings and whether or not appendectomy was done as a primary or secondary operation as well as histologic diagnosis and the presence or absence of fecalith in the specimens as recorded in the surgeons operative notes and the histology report. All the slides of appendectomy cases were retrieved and reviewed. Where slides are missing, fresh sections were taken from tissue cassettes. A positive diagnosis of appendicitis is considered where histologic diagnosis is confirmed whether or not the operative findings concur. A negative histologic diagnosis is taken as normal appendix regardless of the findings in the surgeon's operative notes.
The data were compiled in tabular form and remarks were made to explain peculiarities of individual data. Three authors individually took turns to cross check the data for completeness, accuracy and consistency. Data analysis was done and calculations were aided with the Number Cruncher Statistical (NCSS, LLC Kaysville) software where necessary.
| Results|| |
During the decade under study, there was a total of 1,006,078 outpatient visits with a mean of about 100,000 per year comprising of 763,824 (76%) adults and 242,254 (24%) pediatric-aged patients defined as 12 years or younger. Of this total, 448,607 (44.5%) were males and 557,471 (55.5%) were females. There were a total of 104,873 admissions or about 10,000 admissions per year comprising of 44,417 (42.4%) males and 60,456 (57.6%) females.
Data from the Nigerian Census of 2006 on seven local government areas within 30 km radius of the hospital [Table 1]a and [Figure 1] where patients with appendicitis have their specimens sent to this laboratory for histological study were listed. Populations further away from this hospital where all cases of acute appendicitis would have to come to ABUTH for treatment or their specimens would have to be brought to the ABUTH histopathology laboratory for analysis were noted. The total population count according to the 2006 census in the reference area was 1,423,469 [Table 1]b.
There were a total of 16,267 surgical operations of which appendectomy accounts for 382 (2.6%). The histopathology department received a total of 23,127 solid tissue specimens during the study period. This represents specimens received both from the ABUTH and from other hospitals in the area. Of this total, there were 382 specimens of the appendix representing 1.6% of all surgical solid specimens received.
Of the 382 specimens of appendix received diagnosis of appendicitis was established in 373 cases which form the study population. This gave a mean of 37.2 appendectomies per year or around 3 appendectomies per month in a population of 1,423,469 [Table 1]b. Therefore, this represents a population incidence for appendicitis of 2.6 per 100,000 per year.
There was no gender predilection in our data: Male to female ratio was 185:187 = 1:1 [Table 2] and [Figure 2]. The ages of patients with appendicitis ranged from zero to 74 years. The mean age was 25 years with a standard deviation of 12.3 years and the standard error of the mean was 0.6 and the 95% confidence limit was 23.7-26.2). [Table 3] shows number of cases of appendicitis done in Zaria by year and month [Figure 3].
|Table 3: Number of cases of appendicitis done in Zaria by year and month|
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Evidence of intraluminal fecalith in the specimens as reported in the surgeon`s operative note or from the histopathologic report or both is documented in 354 (93%) of the total 382 specimens.
| Discussion|| |
Appendicitis, a disease thought to have multiple etiological factors, has an intriguing epidemiology.  Our finding of an incidence rate of 2.6 per 100,000 per annum in northern Nigeria came after an exhaustive review of our data as well as the national census figures of 2006 for integrity. This figure is remarkable for being the lowest incidence rate we can find in world literature. Appendicitis shows a stark difference in incidence rate between developed and developing countries that is more than ten folds in some instances such as between Finland and Thailand and between Spain and Ghana. ,,, Significant seasonal variation has been noted in several reports. ,,, Even in the same countries, appendicitis tends to show longer-term temporal difference in incidence that has been thought to be related to changes in social indices like quality of housing and sanitation as exemplified by a standardized incidence rates of 570 per 100,000 in 1955 and 370 per 100,000 in 1987 occurring in Italy and also a standardized incidence rate of 652 per 100,000 in 1970 and 164 per 100,000 in 1999 in Greece. , Obstruction of the lumen of the appendix by fecalith is a specific cause in only about a third of cases of pathologically confirmed appendicitis.  No convincing reports exist in which the population incidence of fecalith and appendicitis have been documented. 
The mean age of presentation in our study is 25 years. However, this contrasts with most studies that suggest peak incidence in the second decade of life. Some authors have suggested that immunological factors may play roles in the pathogenesis of appendicitis. , Barker and colleagues have championed the belief that appendicitis is a disease that prevails in communities with good public health services and housing in place and, by implication, lower in those without these social indices. ,,, This suggests an explanation for the observed low population incidence of appendicitis from developing countries in Asia and Africa. , Surgeons with working experience in sub-Saharan countries like Nigeria are made empirically aware of this difference in the incidence of appendicitis when they move to developed countries in Western Europe and North America.
Most publications on appendicitis from Nigeria suffer from small number of cases even from large urban dwellings as well as a lack of credible census figures with which to calculate annual incidence rates of the disease. ,, This may explain why these authors cannot find any study from Nigeria that calculated a standardized annual incidence rate. This is one of the goals of this study.
The question is "why is appendicitis so uncommon in Northern Nigeria and possibly the rest of the country and region as well?" Ours is an environment where public health indices like sanitation, sewage disposal, quality of water supply is such that water-borne gastrointestinal diseases like poliomyelitis, hepatitis viruses, shigellosis, cholera, typhoid enteritis, giardiasis and amoebiasis are prevalent. Endemic poverty and a lack of strict compliance with sanitary standards enforceable by public health authorities play contributory roles. This describes the type of situation that was prevalent in Europe, particularly in the United Kingdom preceding the introduction of housing edicts that preceded the outbreak of appendicitis in the late 19 th century as reported by Short.  It has been suggested that the Endemicity of these water-borne gastrointestinal pathogens listed above in the water supply of children living in developing countries makes the frontline immune systems in the gastrointestinal systems tolerant of many less potent pathogens whereas in children living in developed countries where these pathogens are rare, the immune system would mount an elaborate response that would cause the lymphoid follicles in the wall of the appendix to hypertrophy to the extent of causing occlusion of the lumen to cause appendicitis irrespective of the presence or absence of fecaliths.  This hypothesis may explain why in both Nigeria and Ghana, for example, typhoid perforation of the ileum vies with appendicitis for supremacy in incidence. ,
If our hypothesis that gastrointestinal infections in this population are tampered with less vigorous immune response that do not lead to sufficient hypertrophy of the lymphoid follicles in the wall of the appendiceal lumen to occlude it holds true, then the relatively high ratio of fecaliths in appendiceal specimens is explained by their mechanical properties which do not lend themselves to immune modulation and runs a relentless course to appendicitis. This is the only logical explanation for the finding of fecaliths in the overwhelming majority of our cases, 93 %.
| Conclusion|| |
Appendicitis has a very low incidence rate (2.6 per 100,000 per annum) in northern Nigeria. Appendectomy represents 2.4% of all surgical operations and the appendix represents 1.6% of all solid operative specimens received for histopathologic studies. Fecaliths as causal factors of appendicitis occur in 93% of specimens with confirmed appendicitis in our series. Larger multi-center studies across the country are needed to validate our observation.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]