Incidence Of Appendicitis Research Articles

Analyzing the dynamics of complicated and uncomplicated appendicitis during the COVID-19 pandemic in Seoul: a multifaceted time series approach.

This study investigated the impact of the COVID-19 pandemic and associated control strategies on the incidence of appendicitis in Seoul, using data from 2018 to 2020 from South Korea's National Health Insurance. We analyzed records of total, complicated, and uncomplicated appendicitis cases, as well as the ratio of complicated to uncomplicated appendicitis, using natural spline and piecewise regression models to identify trends and breakpoints. Bayesian structural time-series (BSTS) models were used to evaluate the causal impact of social distancing on appendicitis incidences. The spline regression analysis indicated decreasing trends in both total and uncomplicated appendicitis cases. Conversely, the incidence of complicated appendicitis and the ratio of complicated to uncomplicated cases increased. Breakpoints for a decline in uncomplicated appendicitis and a rise in the ratio occurred at 31 weeks in 2020 (95% confidence interval [CI], 23.2 to 38.8) and at 33.9 weeks (95% CI, 28.3 to 39.6), respectively. The BSTS model demonstrated a 7.8% reduction in total appendicitis cases (95% credible interval [CrI], -12.0% to -3.3%). It also showed a 17% decrease in uncomplicated cases (95% CrI, -22% to -12%) and increases of 13% (95% CrI, 4.9% to 22.0%) in complicated cases and 39% (95% CrI, 27.0% to 53.0%) in the ratio of complicated to uncomplicated appendicitis. The COVID-19 pandemic resulted in a decrease in both total and uncomplicated appendicitis cases, while the number of complicated cases increased. Reduced medical visits likely accounted for these changes. Strategies are needed to manage changes in disease pathophysiology resulting from altered healthcare utilization during health crises.

Effect of Temperature and Precipitation on Acute Appendicitis Incidence in Seoul: A Time Series Regression Analysis.

This study aimed to investigate the relationship between meteorological factors, specifically temperature and precipitation, and the incidence of appendicitis in Seoul, South Korea. Using data from the National Health Insurance Service spanning 2010-2020, the study analyzed 165,077 appendicitis cases in Seoul. Time series regression modeling with distributed-lag non-linear models was employed. Regarding acute appendicitis and daily average temperature, the incidence rate ratio (IRR) showed an increasing trend from approximately - 10°C to 10°C. At temperatures above 10°C, the increase was more gradual. The IRR approached a value close to 1 at temperatures below - 10°C and above 30°C. Both total and complicated appendicitis exhibited similar trends. Increased precipitation was negatively associated with the incidence of total acute appendicitis around the 50mm/day range, but not with complicated appendicitis. The findings suggest that environmental factors, especially temperature, may play a role in the occurrence of appendicitis. This research underscores the potential health implications of global climate change and the need for further studies to understand the broader impacts of environmental changes on various diseases.

Trends and levels of the global, regional, and national burden of appendicitis between 1990 and 2021: findings from the Global Burden of Disease Study 2021

Appendicitis is a common surgical emergency that poses a large clinical and economic burden. Understanding the global burden of appendicitis is crucial for evaluating unmet needs and implementing and scaling up intervention services to reduce adverse health outcomes. This study aims to provide a comprehensive assessment of the global, regional, and national burden of appendicitis, by age and sex, from 1990 to 2021. Vital registration and verbal autopsy data, the Cause of Death Ensemble model (CODEm), and demographic estimates from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) were used to estimate cause-specific mortality rates (CSMRs) for appendicitis. Incidence data were extracted from insurance claims and inpatient discharge sources and analysed with disease modelling meta-regression, version 2.1 (DisMod-MR 2.1). Years of life lost (YLLs) were estimated by combining death counts with standard life expectancy at the age of death. Years lived with disability (YLDs) were estimated by multiplying incidence estimates by an average disease duration of 2 weeks and a disability weight for abdominal pain. YLLs and YLDs were summed to estimate disability-adjusted life-years (DALYs). In 2021, the global age-standardised mortality rate of appendicitis was 0·358 (95% uncertainty interval [UI] 0·311-0·414) per 100 000. Mortality rates ranged from 1·01 (0·895-1·13) per 100 000 in central Latin America to 0·054 (0·0464-0·0617) per 100 000 in high-income Asia Pacific. The global age-standardised incidence rate of appendicitis in 2021 was 214 (174-274) per 100 000, corresponding to 17 million (13·8-21·6) new cases. The incidence rate was the highest in high-income Asia Pacific, at 364 (286-475) per 100 000 and the lowest in western sub-Saharan Africa, at 81·4 (63·9-109) per 100 000. The global age-standardised rates of mortality, incidence, YLLs, YLDs, and DALYs due to appendicitis decreased steadily between 1990 and 2021, with the largest reduction in mortality and YLL rates. The global annualised rate of decline in the DALY rate was greatest in children younger than the age of 10 years. Although mortality rates due to appendicitis decreased in all regions, there were large regional variations in the temporal trend in incidence. Although the global age-standardised incidence rate of appendicitis has steadily decreased between 1990 and 2021, almost half of GBD regions saw an increase of greater than 10% in their age-standardised incidence rates. Slow but promising progress has been observed in reducing the overall burden of appendicitis in all regions. However, there are important geographical variations in appendicitis incidence and mortality, and the relationship between these measures suggests that many people still do not have access to quality health care. As the incidence of appendicitis is rising in many parts of the world, countries should prepare their health-care infrastructure for timely, high-quality diagnosis and treatment. Given the risk that improved diagnosis may counterintuitively drive apparent rising trends in incidence, these efforts should be coupled with improved data collection, which will also be crucial for understanding trends and developing targeted interventions. Bill and Melinda Gates Foundation.

Exploring the seasonal impact on appendectomy: incidence, patterns, predictors, and healthcare implication of appendectomy at Prince Ali military hospital

Background: This study at Prince Ali military hospital in Al Karak, Jordan, investigates seasonal variations in appendicitis incidence and outcomes, assessing diagnostic and treatment strategies across different seasons. The aim is to understand how seasonal changes influence appendicitis rates and to evaluate the effectiveness of diagnostic methods and treatment approaches. Methods: A retrospective observational study was conducted on 321 confirmed cases of inflamed or perforated appendicitis from March 2021 to February 2024. Patient demographics, dates of surgery, surgical interventions, and postoperative complications were analyzed, with a focus on seasonal trends. Results: Out of 394 reviewed cases, 321 (81.47%) met the inclusion criteria, showing significant seasonal variations in appendicitis incidence. Autumn saw the highest rate of appendicitis cases at 32.09% while the lowest was in Winter (22.12%). Regarding normal appendix, the highest rate was in winter (21.98%), and the lowest was in summer (13.09%). The mean patient age was 25.20 years, with a majority being male (66.36%). Open surgeries were the most common, comprising 91.9% of cases, compared to 8.1% for laparoscopic procedures. Diagnostic analysis revealed a very strong correlation between CT findings and histopathological outcomes (p=3.23×10^-11) and a significant but less strong correlation for ultrasound findings (p=0.000446). These results suggest that both diagnostic methods are effective, with CT scans showing a stronger correlation. The distribution of cases across seasons was 32.087% in autumn, 23.05% in spring, 22.741% in summer, and 22.118% in winter. Conclusions: Significant seasonal peaks in appendicitis are evident, particularly in autumn, driven by changes in diet and viral infections. The superior effectiveness of CT scans during winter highlights the need for adaptive diagnostic strategies across seasons. These findings advocate for healthcare systems to seasonally adjust resources and diagnostics to optimize appendicitis management, with further research needed to expand these insights globally.

High Appendicitis Incidence in Young Adults Calls for Routine Histological Examination

This study explores the histopathological changes associated with appendicitis in appendicectomy specimens from Nasiriyah General Hospital. Employing a retrospective analysis on twenty specimens, it aims to underscore the importance of routine histological examinations. Findings reveal that all specimens were afflicted with appendicitis, featuring notable occurrences of mucosal glandular hyperplasia (43%), mucosal and submucosal layer necrosis (42%), and severe inflammatory cell infiltration (71%). These results highlight the necessity of comprehensive histological assessments in appendicectomy specimens to enhance diagnostic accuracy and improve patient management, particularly among adolescents and young adults. Highlights: All specimens confirmed appendicitis with significant alterations. Routine histological exams critical for accurate diagnosis. Enhanced scrutiny improves adolescent, young adult treatment. Keywords: Appendicitis, Histopathological Changes, Appendicectomy, Histological Examination, Adolescents

Epidemiology, Seasonal Variability, and Factors Associated with Increased Mortality in Patients with Acute Appendicitis in Thailand: A Study Using Data from the National Health Security Office

Objective: The study aimed to study the spatiotemporal distribution of acute appendicitis in Thailand, using a reimbursement dataset from the National Health Security Office, and also analyze for mortality and factors associated with mortality after an appendectomy.Material and Methods: The study used data mining to analyze a reimbursement data set from the Thailand National Health Security Office (NHSO), focusing on the diagnosis of acute appendicitis (K35.2-K35.9). The analysis looked for the incidence trend and seasonal variation of the incidence. The study also analyzed mortality and factors associated with the mortality. A prediction model for mortality was constructed using a decision tree. Results: During the 4 fiscal years of the study period, from October 2016 - September 2020, a total of 287,449 individuals were diagnosed with acute appendicitis, and 272,850 appendectomies were performed, which gave an annual incidence (AI) of 10.8/10,000 person-years. The peak age incidence was in the second decade of life, which had an age-specific AI of 28.4/10,000 person-years. Using a multiplicative model of time series detrending and a decomposition model and a seasonal variation of acute appendicitis, with the highest incidence from May to October, linear regression showed a significant correlation between the incidence of appendicitis and precipitation (r2=0.28, p-value<0.001). The AI of appendicitis was declining and showed an especially large decline in the year 2020, when the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic began. The overall mortality was 2.3%. A significantly higher mortality rate was found in cases with extreme age (pediatric or geriatric), those with co-morbidities (diabetes, hypertension, dyslipidemia, chronic pulmonary disease, chronic kidney disease), and those with complications, especially generalized peritonitis, sepsis, and acute kidney injury. A decision-tree prediction model suggested that sepsis and renal complication were key nodes determining mortality risk in pediatric and geriatric appendicitis. Conclusion: A mortality risk from appendicitis remains in Thai patients, especially the elderly with co-morbidities and those with generalized peritonitis, sepsis, or renal complications. Early diagnosis and improvement in perioperative care in the extreme age groups might improve the mortality figure.

Analisis Asuhan Keperawatan Pada Pasien Dengan Gangguan Sistem Pencernaan

According to data released by the Ministry of Health of the Republic of Indonesia regarding the incidence of appendicitis in Indonesia in 2016, the number of patients with appendicitis in Indonesia reached 591,819 people and increased in 2017 by 596,132 people (Soewito, 2017). The incidence of appendicitis in 2018 reached 7 of the world's population. In 2018 the incidence of appendicitis in most parts of Indonesia is still high. In Indonesia, the number of patients suffering from appendicitis is about 7% of the total population or about 179,000 people (Depkes, 2018). The author's goal is to be able to provide nursing care for post-operative appendectomy patients with acute pain nursing problems. Appendicitis is a painful swelling of the appendix with the management of appendectomy, namely surgery to remove the appendix, surgery is indicated when the diagnosis of appendicitis has been established. The research method used is a case study. Samples were taken according to the inclusion criteria of patients with post-appendectomy digestive system disorders with acute pain problems. The care was carried out for 3 days at the Bekasi District Hospital. Data was collected by: interviews, observations, physical examinations, and documentation studies. Data were analyzed narratively based on a comparison of two patients. Patient data 1 and 2 have been supportive to raise the problem of acute pain and its implementation has been implemented and there are no obstacles.

CURRENT VIEWS AND CLINICAL MANIFESTATIONS OF ACUTE APPENDICITIS AND APPENDICULAR PERITONITIS IN CHILDREN

Acute appendicitis is the most common urgent disease in pediatric surgery (75% of emergency operations). Not only pediatric surgeons, but also pediatricians, pediatric gastroenterologists, and pediatric gynecologists have to deal with appendicitis in children. In childhood, inflammation of the cecum develops rapidly, which causes an increase in destructive changes in the appendix in a relatively short time. With appendicitis in a child, the peritoneum is often involved in the inflammatory process, leading to the development of appendicular peritonitis. The peak incidence of appendicitis in children (more than 80% of cases) is at school age, in preschool children the disease occurs in 13%, in toddlers - in 5% of cases.

Acute Appendicitis Incidence, Diagnostic Markers, and Sequelae; Dallah Hospital-Based Study in Riyadh, Saudi Arabia.

Acute appendicitis is currently considered one of the most common acute surgical diseases of the abdomen and requires emergency surgery. It is also one of the most common abdominal emergencies in both developed and developing countries. The current study is aimed at assessing the specificity and sensitivity of Ultrasound and Computed Tomography in the diagnosis of appendicitis as well as the prevalence of its complications. The association of appendicitis with several laboratory findings will also be evaluated. A retrospective study was conducted at Dallah-Namar Hospital, Riyadh City, Saudi Arabia. 720 patients were differentially diagnosed with appendicitis in the study area. Of these, 618 patients had US abdomen/pelvis, with 15 (2.4%) showing positive findings. Amongst the 203 patients noted to have undergone abdominal CT,8 (4.0%) was found to have positive findings. The sensitivity of the US was determined to be relatively low. Also, serum creatinine was found to be elevated among all patients diagnosed with appendicitis. Further research with a larger sample size is needed to be conducted to further support the current findings.

Incidence, clinical course, and perioperative outcomes of appendicitis in obese: a retrospective study

Objective: This study aimed to assess the incidence of acute appendicitis in obese patients and to comprehensively assess how obesity impacts its clinical course and perioperative outcomes. Methods: A cross-sectional retrospective study was conducted to explore the incidence of appendicitis among obese patients over 2 years (2021-2022) in one center in Taif City, Saudi Arabia. Results: The appendicitis rate was 9.8% among all patients and 2.7% among obese patients. Adult patients had a median interquartile range (IQR) age of 28 (13) years, while children had a (IQR) age of 11. The median of systolic blood pressure (SBP) was affected by their body mass index (BMI) (non-obese vs. obese adults, 120.5 vs. 134 mmHg; p-value = 0.022) (non-obese vs. obese children, 110 vs. 122 mmHg; p-value = 0.048). The median heart rate of obese children was significantly lower than that of non-obese children (73% vs. 95%) (p-value = 0.019). Abnormal computed tomography (CT) findings were higher among obese patients as compared to non-obese (37.5% vs. 1.8%) (p-value = 0.003). The rate of open appendectomy was higher in nonobese patients (adults: 64.5% vs. 25%, p-value = 0.046) (children: 70.9% vs. 0%, p-value = 0.016). Antibiotic administration for appendicitis management was significantly higher among obese children (66.7%) than others (7.7%) (p-value = 0.022). Conclusion: Lower rate of appendicitis was observed in obese patients. This study highlighted the importance of BMI in appendicitis management. BMI can affect vital signs, such as SBP or heartbeat rate, surgical method choice, surgery duration, and antibiotic use.

Association between ulcerative colitis and acute appendicitis - A Mendelian randomization study.

Although the etiology of UC is not clear, some studies show that the appendix may be the starting point of UC, and the incidence of appendicitis is high in patients with UC. We performed a MR analysis to examine whether there is a potential causal relationship between UC and acute appendicitis. Our MR study revealed that the genetic liability of UC (OR, 0.9362; 95% CI 0.9014 - 0.9723; p = 0.00064) was associated with a decreased risk of acute appendicitis. More research is needed in the future to support our findings and better explain why UC reduces the risk of acute appendicitis.

Apendicite aguda em um adolescente com situs inversus totalis: relato de caso

Appendicitis is the most common surgical emergency in pediatrics, being present in 1% to 8% of children with acute abdominal pain. The classical clinical presentation is characterized by the presence of acute migrating abdominal pain in the right iliac fossa. However, in patients with situs inversus totalis, the pain manifests in the left iliac fossa, which may delay the diagnosis and predispose to the development of complications. Thus, the aim of this study is to report a case of appendicitis in an adolescent with situs inversus totalis. METHODS: This study is case report of appendicitis in an adolescent with situs inversus totalis. The research was submitted to the Ethics in Human Research Committee and approved under CAAE number 53591321.0.0000.5237. RESULTS: The incidence of appendicitis in patients with situs inversus totalis is 0.016% to 0.024%. Due to the atypical clinical presentation in these patients, there is a tendency to delay the diagnosis of appendicitis, especially when the situs inversus totalis was not previously identified. Thus, there is a greater risk of developing severe complications such as intestinal perforation and sepsis, which considerably increases morbidity and mortality. CONCLUSIONS: We emphasize the importance of listing appendicitis as a possible diagnosis in patients with acute abdominal pain in the left iliac fossa because of the possibility of situs inversus totalis.

An unusual case of the Amyand hernia with perforated appendicitis and a sessile serrated lesion within a recurrent inguinal hernia

The Amyand hernia is a rare type of inguinal hernia where the appendix is located within the hernial sac. It is present in less than 1% of inguinal hernias and in 0.13% of cases, it is associated with complications including acute appendicitis and perforation. This case details an 81-year-old female with recurrent Amyand hernia with perforated appendicitis and a sessile serrated lesion. A literature review was conducted to identify existing cases of the Amyand hernia and neoplasm or recurrent inguinal hernia. Fifteen cases of neoplastic appendix within an Amyand hernia were identified in the literature. All cases found acute appendicitis, three of which were perforated. Histology varied from adenocarcinoma, goblet cell, carcinoid, fibroma, and mucinous cystadenoma. There were nine identified cases of Amyand hernia within a recurrent inguinal hernia. Seven of these cases had acute appendicitis, three of which were perforated, whilst one was gangrenous. All cases performed an appendicectomy, and various open techniques were used for hernia repair with or without mesh. The most interesting finding of the literature review was that Amyand hernia is rarely diagnosed pre-operatively, and that there was a high incidence of appendicitis when in the presence of a neoplastic appendix or a recurrent inguinal hernia. This paper highlights the first reported case of an Amyand hernia with a simultaneous neoplasm and recurrent inguinal hernia, which was managed using a laparoscopic approach without hernia repair.

Seasonal Variation in Cases of Acute Appendicitis Incidence

Seasonal Variation in Cases of Acute Appendicitis Incidence

An Update on Acute Appendicitis in Lebanon: Insights From a Single-Center Retrospective Study.

Background Acute appendicitis is the most common surgical emergency worldwide with scarce reports about its prevalence in the Middle East. To date, no epidemiological article has described the incidence of appendicitis in Lebanon. Our primary objective was to estimate the rate of appendicitis in a single center in Lebanon. Our secondary objectives included identifying differences between simple and complicated appendicitis regarding demographics, pre and postoperative characteristics, and symptoms and signs of appendicitis. Methodology A retrospective study was conducted at a single central university hospital in Lebanon. Patients with a clear diagnosis of acute appendicitis were included. Pregnant women, lactating women, patients with organ dysfunction, and patients younger than 18 years old or older than 80 years old were excluded. We reviewed and collected the data of patients who presented to the hospital between November 2018 and November 2019 and November 2020 and November 2021. Results A total of 95 patients were included in our study, with 35 women and 60 men. The mean body mass index of patients with simple appendicitis was 19.14 ± 9.66 kg/m2 compared to 18.97 ± 10.37 kg/m2 in patients with complicated appendicitis (p = 0.94).A total of 42.3% of patients who used antibiotics 24 hours after the operation had simple appendicitis, whereas 20.8% had complicated appendicitis (p = 0.004). Conclusions Antibiotic usage and thelength of hospital staywere correlated with the severity of appendicitis, as reported in the literature. Further randomized studies with a larger number of patients and covering several hospitals in Lebanon are warranted.

Age-related disparities and trends in national healthcare spending formanagement of appendicitis in the United States: A retrospective cost-analysis.

Changes in clinical care for appendicitis have impacted healthcare use associated with treatment. We evaluated national trends and assessed factors associated with healthcare costs for appendicitis in the United States. The Disease Expenditure Project, the Global Burden of Disease study, and the National Inpatient Sample were used to estimate total national expenditures, per-capita costs for incident cases, and factors associated with inpatient costs for appendicitis management, respectively. The national estimates of appendicitis costs were obtained from 1996 to 2016. Appendicitis incidence was estimated to calculate per-capita costs. After application of survey weights for the stratified sample design, 191,180 weighted discharges for appendicitis from the 2016 National Inpatient Sample study were evaluated. The Disease Expenditure Project and the Global Burden of Disease study were used to estimate total and per-capita spending. Temporal trends were evaluated using joinpoint regression, expressed as annual percent change. Multivariable linear regression was used to evaluate patient factors associated with total hospital charges. In 2016, total spending on appendicitis was $9.3 billion (95% confidence interval: $8.0-$10.8], a 2-fold increase from $4.7 billion ($4.0-$5.3) in 1996. Per-capita spending decreased significantly after 2011 (annual percent change -3.7% [-4.4% to -2.9%]). Patients ≥65 years accounted for 64.1% (61.1%-67.3%) of total spending for appendicitis. The hospital charges for older patients were significantly higher among those undergoing appendectomy. Overall healthcare spending for appendicitis has doubled from 1996 to 2016, but per capita spending has decreased since 2011, driven by improved efficiency of inpatient care. Nearly two-thirds of spending is on patients ≥65 years, with significantly higher costs associated with surgical management in this population.

Incidence of appendicitis during SARS-CoV-2 pandemic quarantine

Incidence of appendicitis during SARS-CoV-2 pandemic quarantine

Effects of COVID-19 Pandemic on the Frequency of Complicated Appendicitis in Pediatric Populations

Background: The clinical course of acute appendicitis, one of the most common diseases needing surgical intervention in children, was affected by the coronavirus disease 2019 (COVID-19) pandemic. The global fear and panic about the outbreak and governmental decisions on lockdowns and restrictions led to an increasing number of complicated forms of appendicitis. Objectives: This study aimed to compare different aspects of appendicitis and its complications between the pre-pandemic and pandemic periods. Methods: In a retrospective cross-sectional analytical study, we enrolled all patients with a diagnosis of acute appendicitis for two consecutive years. Only children under 14 years of age were included in the study. The patients were divided into two groups based on the time of disease presentation, the pre-pandemic and pandemic periods. Demographic features, as well as clinical, laboratory, and imaging findings, were compared between the two groups. Results: Out of 369 patients included in the study, 173 were placed in the pre-pandemic group. There was no significant change in the incidence of appendicitis between the two periods (P = 0.232). However, the incidence of complicated appendicitis increased remarkably during the pandemic (27% vs. 11%, P < 0.001). No substantial differences were found in parameters like age, sex, laboratory findings, and the length of hospital stay between the two groups (P > 0.005). The patients who tested positive for COVID-19 had a significantly higher hospitalization duration (P < 0.001). Conclusions: Our results suggested that the rate of complicated appendicitis was substantially higher during the pandemic compared to the pre-pandemic time. Also, the proportion of midline laparotomy was significantly higher after the outbreak. These findings suggested that delays in care provision during the COVID-19 outbreak could have probably contributed to the rise in the incidence of complicated appendicitis in children.

The Incidence and Awareness of Appendicitis among Female Students in Student's Dorm of Mohamed Osman Saror in Almatama Town, 2021

Background: Appendicitis is inflammation of appendix, which a small tube attached to large intestine. Material and Methods: This cross-sectional descriptive study was carried out from Sep to Dec, 2021, in student dorm of M.O. Saror, in Almatma town. Aimed to measuring the incidence of Appendicitis among female students and her awareness about disease. One Hundred female students was selected and interviewed randomly, and questionnaire was used to collecting data from respondents. The findings of this study showed that the incidence of appendicitis was 16% during the year 2021. 85% was known appendicitis, Also the psychological and economic factors are most effects resulting from appendicitis. Recommendations: Study recommended to decreasing intake spicy and seeds foods carefully, and intake foods can prevent from appendicitis like fenugreek, and barley.

Relationship between clozapine exposure and the onset of appendicitis in schizophrenia patients: a retrospective cohort study

ObjectiveClozapine may cause serious side effects despite benefits in patients with schizophrenia. Thus, an accurate understanding of the side-effect profile of clozapine is extremely important in the management of its administration to patients with schizophrenia. Our aim was to validate the relationship between clozapine exposure and appendicitis onset in patients with schizophrenia.MethodsIn this study, we retrospectively compared the incidence and cumulative incidence of appendicitis in patients with schizophrenia with and without a history of clozapine exposure. Among the patients with schizophrenia who visited our hospital between June 2009 and August 2021, we extracted those with a history of clozapine treatment. Patients with a history of taking clozapine were defined as the clozapine exposure group, while the others were defined as the clozapine non-exposure group. Patients with a history of appendectomy before their initial visit to our hospital or with a history of clozapine use at other hospitals were excluded.ResultsThere were 65 patients in the clozapine exposure group and 400 patients in the clozapine non-exposure group who met the inclusion criteria. The exposure group exhibited a remarkably higher incidence of appendicitis during the observation period than the non-exposure group (863 cases vs. 124 cases per 100,000 person-years). In particular, if limited to the period of clozapine exposure, the incidence of appendicitis is extremely high, at 2,086 cases per 100,000 person-years. Moreover, multivariable analysis showed that clozapine exposure was an independent factor contributing to the onset of appendicitis.ConclusionsClozapine exposure is associated with appendicitis onset in patients with schizophrenia.