Impact of age at appendectomy on development of type 2 diabetes: A population-based cohort study

Exploring the Immunological Role of the Microbial Composition of the Appendix and the Associated Risks of Appendectomies

The appendix, an integral part of the large intestine, may serve two purposes. First of all, it is a concentration of lymphoid tissue that resembles Peyer's patches. It is also the main location in the body for the creation of immunoglobulin A (IgA), which is essential for controlling intestinal flora's density and quality. Second, the appendix constitutes a special place for commensal bacteria in the body because of its location and form. Inflammation of the appendix, brought on by a variety of infectious agents, including bacteria, viruses, or parasites, is known as appendicitis. According to a number of studies, the consequences of appendectomies may be more subtle, and may relate to the emergence of heart disease, inflammatory bowel disease (IBD), and Parkinson's disease (PD), among other unexpected illnesses. A poorer prognosis for recurrent Clostridium difficile infection is also predicted by the absence of an appendix. Appendectomies result in gut dysbiosis, which consequently causes different disease outcomes. In this review, we compared the compositional differences between the appendix and gut microbiome, the immunological role of appendix and appendix microbiome (AM), and discussed how appendectomy is linked to different disease consequences.

Non-culture-based studies of the appendiceal microbiota: a systematic review

Aims: To review studies examining the appendiceal microbiota and microbial changes in acute appendicitis. Methods: After a systematic literature search, 11 studies examining the appendiceal microbiota (414 samples) using non-culture-based methods were included. Results: The appendiceal microbiota showed decreased α-diversity compared with fecal microbiota. Inflamed and uninflamed appendices showed differences in β-diversity, and there was an increased abundance of oral-associated bacteria in inflamed versus uninflamed appendices. Conclusion: The appendiceal microbiota exhibits lower α-diversity than the fecal microbiota, with an increased abundance of oral-associated bacteria. Compared with uninflamed appendices, the appendix microbiota in acute appendicitis also showed increased abundance of oral-associated bacteria, but no bacterial profile unique to either complicated or uncomplicated appendicitis was found.

Impact of Appendectomy on Gut Microbiota

Background: Considered vestigial from the classic point of view, the vermiform appendix has long been the subject of intensive studies. The recent understanding of appendix function in the context of unique architecture and bacterial complexity and density allows considering it as a safehouse for intestinal biodiversity. Methods: This review analyzes and assesses the current state of scientific knowledge regarding the role of the vermiform appendix in normal gut microbiota maintenance as a crucial factor of host homeostasis. It also highlights the difference in microbial composition between the large bowel and the appendix, as well as the association between the surgical excision, appendectomy, and dysbiosis-induced diseases. In addition, the review discusses the results of epidemiologic studies on appendectomy as a risk factor for the initiation of gastrointestinal carcinogenesis. It also highlights the association between appendectomy and a series of chronic inflammatory and neurologic disorders, including inflammatory bowel disease.

A link between appendectomy and gastrointestinal cancers: a large-scale population-based cohort study in Korea

An association between appendectomy and subsequent gastrointestinal (GI) cancer development has been postulated, although the evidence is limited and inconsistent. To provide clarification, we investigated the link between appendectomy and GI cancers in a large nationwide appendectomy cohort. This cohort was derived from the claims database of the National Health Insurance Service in South Korea and comprised 158,101 patients who had undergone appendectomy between 2007 and 2014. A comparison cohort of 474,303 subjects without appendectomy was selected after 1:3 matching by age and sex. The incidence of GI cancers after appendectomy was observed, and risk factors for GI cancers were determined by using a multivariable-adjusted proportional hazards model. Appendectomy did not significantly increase the incidence of GI cancers in the overall population (1.529 and 1557 per 1000 person-years in the non-appendectomy and appendectomy cohorts, respectively). However, appendectomy significantly increased the incidence of GI cancers in subgroups consisting of elderly (≥ 60 years) patients (adjusted HR, 1.102; 95% confidence interval, 1.011-1.201; p = 0.028) or women (adjusted HR, 1.180; 95% confidence interval, 1.066-1.306; p = 0.001).

Risk of irritable bowel syndrome in patients who underwent appendectomy: A nationwide population-based cohort study

BACKGROUND

Appendectomy is one of the most common surgical procedures; however, the possible long-term consequences have not been fully explored. The appendix has been associated with microflora of the gut and immune functions. However, literature examining the relationship between prior appendectomy and the risk of irritable bowel syndrome (IBS) is lacking. The aim of this study was to evaluate the risk of irritable bowel syndrome for patients who underwent appendectomy by using a nationwide longitudinal population-based cohort.

METHODS

Data from this study was collected from Taiwan's National Health Insurance Research Database (NHIRD), a population-based database. We identified 12,760 patients who underwent appendectomy between January 1, 2000 and December 31, 2012. A total of 9236 patients who had appendectomy (case group) were randomly matched with 9236 patients who had not undergone appendectomy (control group) in a ratio of 1:1 by means of propensity scores. The hazard ratio (HR) of IBS was calculated by multiple Cox regression. Furthermore, sensitivity test and stratified analysis were performed.

FINDINGS

The incidence rate of IBS was 51.30 per 10,000 person-years in patients having appendectomy, more than the 35.28 per 10,000 person-years in patients not having appendectomy. Patients who underwent appendectomy had 1.46-fold risk of IBS compared to patients not having appendectomy (HR, 1.46; 95% CI, 1.24-1.72). Stratified analysis revealed that the higher HR of 1.55 (95% CI, 1.18-2.04) in patients <40 years old, and particularly within the first 5 years follow-up period of undergoing appendectomy. In addition, patients diagnosed with fibromyalgia had a greater risk of suffering IBS after appendectomy (HR, 1.41; 95% CI, 1.04-1.92).

INTERPRETATION

Patients with appendectomy have a higher incidental risk of IBS than the control population. The risk is higher for patients under 40 years old and those who received appendectomy within 5 years. Physicians could take this into consideration for treatment plans of patients who have underwent this surgery. Further research on the pathogenesis of this association is required.

FUNDING

This work was supported by grants from the Ministry of Health and Welfare, Taiwan (MOHW108-TDU-B-212-133004), China Medical University Hospital, Academia Sinica Stroke Biosignature Project (BM10701010021), MOST Clinical Trial Consortium for Stroke (MOST 108-2321-B-039-003-), Tseng-Lien Lin Foundation, Taichung, Taiwan, and Katsuzo and Kiyo Aoshima Memorial Funds, Japan.