The Global Incidence of Appendicitis - An Overview

Introduction

Appendicitis is the inflammation of the appendix. It is an acute condition that is common in children and adults. It presents as abdominal pain near the navel that later localizes to the right side. It can occur with or without perforation. Appendicitis is the most frequent abdominal emergency surgery across the world. Incidence measures the rate of newly identified cases in a population for a specific time. The global incidence of appendicitis has increased over the years.

What Are the Factors Affecting the Global Incidence of Appendicitis?

The global burden of disease (GBD) tool provides a complete picture of the associated death rates (mortality) and disability (morbidity) worldwide. It assesses health loss from various diseases, injuries, and risk factors. A recently published study has revealed the global burden of appendicitis from 1990 to 2019 in 204 countries and territories via the GBD tool. The global incidence has increased by 63.55 %. Age standardization is used to compare different mortality rates, as age has an important impact on death. Age standardization is the average age-specific mortality rate per 100,000 individuals. Out of the 204 countries, South Asia experienced the largest increase in age-standardized incidence rates. The factors on which the incidence rate depends are:

1. Socio-Demographic Index: Socio-demographic index (SDI) evaluates the population characteristics. Age, gender, education level, socio-economic status, and ethnicity are some variables used. SDI is a measure of socio-demographic development. From 1990 to 2019, the number of new cases increased in all the countries. However, the highest age-standardized incidence rate (ASIR) was found in low-middle SDI countries.

2. Age and Gender: The burden of incidence was more in women worldwide. It is because the incidence in women was higher in all age groups except for ages 1 to 4 and 30 to 39. ASIR was highest for women under 70 years. However, the incidence rate was highest for both genders in the age group between 15 to 19. Therefore, it supports the statement that appendicitis is most common between 10 to 20 years of age. Previous studies have reported a male-female ratio of 1.4:1. Still, the increased incidence among males explained in those studies was done in a limited group of patients.

3. Socio-Economic Status: Socioeconomic status (SES) is the outcome of an individual’s education, income, and occupation. A 2020 study assessed the geographic association between socioeconomic status and appendicitis incidence. In addition, the authors checked the distribution of acute and perforated appendicitis. They noted that higher income and education are strongly linked to a decreased incidence of acute appendicitis.

4. Weather: Appendicitis follows a seasonal pattern. It has been observed that the incidence of acute appendicitis increases during summer. It might be due to several factors. First, increased dehydration and constipation may occur during summer. Besides, diet changes expose the gut to infections. A 2022 study revealed increased incidence with a raised ambient temperature. Also, a raised temperature increases the risk of hospitalization.

5. Family History: A positive family history predisposes an individual to increased risk due to the genetic susceptibility of appendicitis. A study was conducted on 116 appendicitis patients to assess whether family history is a predictor. About 38 % of the patients had a positive family history. The authors concluded that family history is an independent predictor of appendicitis.

6. Lymphoid Hyperplasia: Lymphoid tissues support immune responses. The appendix is rich in lymphoid cells. Lymphoid hyperplasia is an increase in lymphoid cells. Diffuse or focal lymphoid hyperplasia can obstruct the appendix leading to appendicitis.

Epidemiology is a measure of incidence and disease distribution. A study done in India revealed the epidemiological aspects of 130 cases of appendicitis in a rural set-up for three years. About 45 % of the patients constituted the 11 to 20 age group. In males, the incidence was highest in 21 to 30 years. On the other hand, females were the most affected in the age group of 11 to 20 years. The non-vegetarians and vegetarians comprised 54 % and 15 %, respectively. Seasonal trends were also observed. Appendicitis occurred mostly in the spring and less in the summer. Surgical exploration of the patients revealed acute appendicitis in 89 % of the cases. Perforated appendicitis constituted fewer cases. However, the authors noted stability in the incidence of appendicitis in the three years.

The dietary risk factors include low fiber and high meat, high sugar intake, and less water consumption. The environmental risk factors are exposure to dust and allergens, cigarette smoking, and environmental infections. Furthermore, many countries observed an increased incidence of severe appendicitis during the COVID-19 outbreak. The lockdown aggravated the disease's course as many patients hesitated to seek emergency treatment.

What Are the Data Related to the Global Incidence of Appendicitis?

1. Appendicitis Burden at the Global Level: There were 17.7 million new appendicitis cases worldwide in 2019. About 34,000 deaths were reported. The ASIR was about 230 per 100,000 individuals. However, there has been a decrease in the mortality rate to date. It may be due to advancements in diagnostic and treatment modalities.

2. Appendicitis Burden at the Regional Level: The highest ASIRs were recorded in Latin America and the high-income Asia-Pacific areas. The lowest ASIRs were observed in the Sub-Saharan African countries.

3. Appendicitis Burden at the National Level: The appendicitis ASIR was highest in Bangladesh, with about 1350 cases per 100,000 individuals. Next, Bhutan was affected, followed by Peru. On the contrary, Ethiopia, Kenya, and Indonesia had the lowest ASIRs.

The increased incidence burden might be due to population increase. Another study observed the global incidence of appendicitis and appendectomy (appendix removal). The authors reported a rising incidence of appendicitis and appendectomy in newly industrialized countries in Asia, the Middle East, and South America. In Western countries, an escalated incidence during the 1900s was seen. However, appendicitis became uncommon during the 20th century. It holds for both perforated and non-perforated appendicitis. The incidence of appendectomy has also declined. A minimally invasive procedure is favorable compared to open surgery. Moreover, appendectomy remains a clinical and economic burden.

Conclusion

Appendicitis persists as a global health concern. Analyzing the global burden and incidence of appendicitis is important. As a result, healthcare systems can establish effective management strategies for appendicitis treatment and prevention. Further, the awareness of the global evolution of appendicitis is fruitful in health resource utilization.