Appendicitis Associated With Clozapine: Analyses Based on a Spontaneous Reporting System Database in Japan.

BACKGROUND: An association between appendicitis and clozapine has recently been reported; however, few studies other than case reports have investigated this association. Therefore, we aimed to investigate the association between appendicitis and clozapine, using a large spontaneous reporting database in Japan. METHODS: Japanese Adverse Drug Event Report data were used in this study, and patients who had received clozapine or nonclozapine second-generation antipsychotics (NC-SGAs) available in Japan were included. To compare the reporting frequency of appendicitis associated with clozapine and NC-SGAs, we calculated the adjusted reporting odds ratio using logistic regression models, adjusting for age group, sex, and anticholinergic use. We conducted a time-to-event analysis to examine the time to onset of appendicitis associated with clozapine. RESULTS: In total, 8921 patients were included in this study, of whom 85 (1.0%) had appendicitis. Of these, 83 patients had received clozapine. Appendicitis was significantly more frequently reported with clozapine than with NC-SGAs. Time-to-event analysis showed that the risk of developing appendicitis associated with clozapine increased over time. CONCLUSIONS: Clozapine was associated with a higher risk of appendicitis than NC-SGAs, which increased with time. These findings suggest that clinicians need to pay greater attention to the risk of developing appendicitis during clozapine treatment.

Characteristics of appendicitis after immune checkpoint inhibitor therapy among cancer patients.

PURPOSE: Immune checkpoint inhibitor (ICI) therapy has revolutionized cancer care but is associated with immune-related adverse events (irAEs). Recent case reports raised the concern that acute appendicitis may be an irAE. In this study, we sought to describe the disease course of post-ICI therapy appendicitis and its associated complications. METHODS: Adult patients who had an International Classification of Diseases code for appendicitis within the first 2 years after initiating ICI therapy from January 2010 to April 2021 and who had imaging evidence of appendicitis were studied retrospectively. RESULTS: 13,991 patients were identified who had ICI exposure during the study period, 44 had codes for appendicitis, 10 of whom met the inclusion criteria. Their median age at the time of diagnosis was 59 years. The median time from ICI therapy initiation to appendicitis onset was 188 days. The most common presenting symptoms were abdominal pain (70%) and fever (40%). Abscesses were present in two patients, and a perforation was present in one. All 10 patients received broad-spectrum antibiotics. Five patients needed surgery or interventional radiology drainage. Nine patients had resolution of appendicitis symptoms after treatment. CONCLUSION: Post-ICI therapy appendicitis is rare but presents similarly to and has similar complications rates as conventional appendicitis. Appendectomy remains the mainstay of treatment, but its use can be limited in cancer patients. The decision to continue ICI therapy remains at the discretion of the clinician. Further studies are needed to bring awareness to and advance the understanding of this clinical entity.

Medications and the risk of perforated appendicitis: an adverse event report system (FAERS) database analysis.

OBJECTIVE: Different classes of medication have been reported in the literature to be associated with an increased risk of gastrointestinal perforation. However, little is known about the risk of drug-induced perforated appendicitis. METHODS: We analyzed the Food and Drug Administration Adverse Event Reporting System (FAERS), a large national database of reported adverse events associated with post-market FDA-approved medications from January 2011 to October 2021. Patients of any age group with appendiceal perforation were included. Duplicated reports and other anatomical areas of gastrointestinal tract perforation outside the appendix were excluded. RESULTS: During the study period, 474 event cases met inclusion criteria, of which 284 were females. Most reports of perforation occurred in patients 40-49 years (n = 110) and 50-59 years (n = 144). Cases of perforated appendicitis occurred in patients being treated for multiple sclerosis (31.5%) and rheumatoid arthritis (17.1%). Perforation occurred in patients receiving interferon beta 1a (23.6%), adalimumab (17.9%), etanercept (14.1%), natalizumab (12.2%), clozapine (10.1%), infliximab (9.9%), bevacizumab (7.2%), and calcium chloride (4.9%). Sixteen fatal outcomes were reported. CONCLUSION: Findings from the FAERS database highlight the risk of appendiceal perforation in the context of different classes of drugs. Larger pharmacovigilance studies are needed to confirm these observations.

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

OBJECTIVE: Clozapine 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. METHODS: In 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. RESULTS: There 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. CONCLUSIONS: Clozapine exposure is associated with appendicitis onset in patients with schizophrenia.

Perforated appendicitis induced by pembrolizumab: a case report and review of the literature.

Monoclonal antibodies against programmed cell death protein 1 (PD-1) and PD-1 ligand 1 (PD-L1) are the main representatives in the field of immunotherapy and their indications are constantly increasing in medical oncology and hematology during the last decade. They are associated with long-lasting responses and an acceptable toxicity profile, although they may infrequently cause life-threatening complications requiring prolonged hospitalization or urgent interventions. With the current report, we present the case of a 75-year-old woman diagnosed with stage IV lung adenocarcinoma, who developed acute abdominal pain without preceding symptomatology while on pembrolizumab-pemetrexed maintenance treatment. A contained rupture of the appendix was found, for which she was managed conservatively. Subsequent endoscopic as well as histopathological findings from biopsies obtained via colonoscopy associated the clinical and imaging findings with grade 4 immune-mediated colitis. Interestingly, high-grade colitis is more frequent with anti-CTLA-4 agents in comparison to anti-PD-1 agents; moreover, most cases of anti-PD-1-mediated colitis present with preceding symptomatology (like diarrhea or vomiting), while cases or colonic perforation are extremely rare if ever described.

Antibiotics during childhood and development of appendicitis-a nationwide cohort study.

BACKGROUND: Appendicitis is a common disease with a lifespan risk of approximately 8%. The full range of specific causes for the disease remains elusive, but an aberrant microbiota have been identified as a potential risk factor. AIM: To investigate if use of antibiotics in a paediatric population increases the risk of appendicitis in childhood and adolescence METHODS: We conducted a cohort study from 1 January 1995 to 31 December 2014. A total of 1 385 707 children (0-19 years of age) including 7 406 397 antibiotic prescriptions and 11 861 cases of appendicitis were included. Primary outcome was appendicitis requiring appendectomy according to previous use of antibiotics. Appendicitis and appendectomy were identified from nationwide hospital records, and exposure to antibiotics was identified from nationwide prescription register. Rate ratios (RRs) with 95% confidence intervals were estimated from Poisson and logistic regression models. RESULTS: Children who received at least one course of antibiotics were at increased risk of developing appendicitis compared to unexposed children (adjusted RR 1.72 [95% confidence interval 1.61-1.85]), mean age of developing appendicitis was 9.8 years (SD 4.1 years). The RR of appendicitis increased by 1.04 (1.04-1.04) per antibiotic course. A higher risk of appendicitis was observed in children exposed to antibiotics within the first 6 months of life (RR 1.46 [1.36-1.56]) and children exposed to broad-spectrum antibiotics (RR 1.33 [1.27-1.39]). After adjustment for number of antibiotic courses, the association between early age of antibiotic exposure and risk of appendicitis and the association between exposure to broad-spectrum antibiotics and the risk of appendicitis both disappeared. CONCLUSION: Children who receive antibiotics are at increased and dose-dependent risk of appendicitis. The underlying mechanisms merit further investigation.

Near Real-Time Surveillance to Assess the Safety of the 9-Valent Human Papillomavirus Vaccine.

BACKGROUND AND OBJECTIVES: Human papillomavirus is the most common sexually transmitted infection in the United States and causes certain anogenital and oropharyngeal cancers. The 9-valent human papillomavirus vaccine (9vHPV) provides protection against additional types not included in the quadrivalent vaccine. We conducted near real-time vaccine safety surveillance for 24 months after the vaccine became available in the Vaccine Safety Datalink. METHODS: Immunizations and adverse events were extracted weekly from October 2015 to October 2017 from standardized data files for persons 9 to 26 years old at 6 Vaccine Safety Datalink sites. Prespecified adverse events included anaphylaxis, allergic reaction, appendicitis, Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy, injection site reaction, pancreatitis, seizure, stroke, syncope, and venous thromboembolism. The observed and expected numbers of events after 9vHPV were compared weekly by using sequential methods. Both historical and concurrent comparison groups were used to identify statistical signals for adverse events. Unexpected signals were investigated by medical record review and/or additional analyses. RESULTS: During 105 weeks of surveillance, 838 991 doses of 9vHPV were administered. We identified unexpected statistical signals for 4 adverse events: appendicitis among boys 9 to 17 years old after dose 3; pancreatitis among men 18 to 26 years old; and allergic reactions among girls 9 to 17 years old and women 18 to 26 years old after dose 2. On further evaluation, which included medical record review, temporal scan analysis, and additional epidemiological analyses, we did not confirm signals for any adverse events. CONCLUSIONS: After 2 years of near real-time surveillance of 9vHPV and several prespecified adverse events, no new safety concerns were identified.

Effects of ambient air pollution exposure on frequency of hospital admissions for appendicitis in Taipei, Taiwan.

The relationship between exposure to ambient air pollutants and hospital admissions for appendicitis is not known. This study examined whether an association existed between air contaminant levels and frequency of hospital admissions for appendicitis in Taipei, Taiwan. Ambient air pollution and hospital admission data for Taipei were obtained for 2009-2013. Relative risk (RR) of hospital admissions was estimated using a case-crossover approach, controlling for weather variables, day of the week, seasonality, and long-term time trends. In the single pollutant model, on warm days (> 23°C), number of appendicitis admissions was significantly associated with particulate matter (PM2.5), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3). On cool days (< 23°C), a significant rise in number of admissions for appendicitis was related to PM10, NO2, and O3 concentrations. In the two-pollutant models, on warm days, NO2 and O3 were significantly associated with increased number of admissions for appendicitis when combined with each of the other pollutants. On cool days, NO2, O3, and PM10 remained significant for higher appendicitis admission cases in all two-pollutant models. In conclusion, higher levels of ambient air pollutants may be associated with increase in the risk of hospital admissions for appendicitis in Taipei.

Acute appendicitis presenting as pneumoperitoneum in a teenage boy undergoing chemotherapy.

Chemotherapy of paediatric haematological malignancies can induce infectious complications of the gastrointestinal tract, with predilection of the ileocaecal region. Common causes of right lower abdominal pain in the febrile patient with neutropaenia include acute appendicitis, typhlitis, ileus and intussusception. In this case report, we describe a teenage boy with acute appendicitis presenting with pneumoperitoneum during his course of chemotherapy. The incidence, aetiology, diagnosis, investigations and management of this uncommon presentation in a common disease are discussed. The controversial topic of the management of acute appendicitis in a febrile patient with neutropaenia is also reviewed and discussed.

Periappendicitis during adalimumab treatment for ileocecal Crohn's disease in a 29-year-old male.

A 29-year-old male was diagnosed with ileocolic Crohn's disease (CD) approximately 2 years ago. Adalimumab was prescribed as CD remission induction therapy. Three months after beginning adalimumab, watery diarrhea and lower abdominal pain developed. He was admitted under a diagnosis of CD exacerbation. Despite fasting and antibiotic treatment, symptoms of acute panperitonitis appeared. He was diagnosed as acute appendicitis and we performed emergency surgery for peritoneal drainage and ileocecal resection on the fifth hospital day. We diagnosed periappendicitis based on the operative findings. This is the first report of periappendicitis with CD during adalimumab treatment.

Perforated appendicitis after intravenous immunoglobulin therapy in a term neonate with haemolytic jaundice.

Neonatal appendicitis is a rare clinical condition that may cause high morbidity and mortality if diagnosis is delayed. There is usually an underlying disease; it can also be a localized form of necrotizing enterocolitis. Here, we present a term neonate who was treated with intravenous immunoglobulin because of severe isoimmune hemolytic jaundice. The patient developed abdominal symptoms within 10 hours of therapy, was diagnosed with acute perforated appendicitis and completely recovered after surgery.

Meralgia Paresthetica as a Presentation of Acute Appendicitis in a Girl With Acute Lymphoblastic Leukemia.

A 7-year-old girl with Philadelphia chromosome-positive acute lymphoblastic leukemia developed recurrent fever and meralgia paresthetica (MP) during chemotherapy, which resolved after administration of antibiotics. Five months after the onset of these symptoms, enhanced computed tomography showed a periappendiceal abscess extending into the psoas muscle. The cause of her fever and MP was thought to be appendicitis, which probably developed during induction chemotherapy but did not result in typical abdominal pain. Patients with recurrent fever and MP should be evaluated by imaging examinations including computed tomography to search for appendicitis.

Barium-induced appendicitis mimicking accidental ingestion of a dental metal crown in radiological findings.

Barium appendicitis is a rare complication that has only been reported in a small number of case reports in the medical literature. A 57-year-old male presented to the emergency room with a sudden onset of sharp right lower quadrant abdominal pain. He had undergone contrast barium examination of his stomach 2 months previously as part of a periodic examination for gastric cancer. The radiological findings showed that the shape and radiopaque levels were similar to those of a dental metal crown silhouette. The patient was strongly suspected to have a localized intra-abdominal abscess due to ileocaecal perforation with a foreign body such as a dental metal crown. Emergency surgery revealed acute phlegmonous appendicitis. The resected specimen demonstrated a phlegmonous appendix which contained solid coproma. Pathological diagnosis and composition analysis confirmed the onset of appendicitis to be a result of the patient's ingestion of barium sulfate.

Ambient ozone concentrations and the risk of perforated and nonperforated appendicitis: a multicity case-crossover study.

BACKGROUND: Environmental determinants of appendicitis are poorly understood. Past work suggests that air pollution may increase the risk of appendicitis. OBJECTIVES: We investigated whether ambient ground-level ozone (O3) concentrations were associated with appendicitis and whether these associations varied between perforated and nonperforated appendicitis. METHODS: We based this time-stratified case-crossover study on 35,811 patients hospitalized with appendicitis from 2004 to 2008 in 12 Canadian cities. Data from a national network of fixed-site monitors were used to calculate daily maximum O3 concentrations for each city. Conditional logistic regression was used to estimate city-specific odds ratios (ORs) relative to an interquartile range (IQR) increase in O3 adjusted for temperature and relative humidity. A random-effects meta-analysis was used to derive a pooled risk estimate. Stratified analyses were used to estimate associations separately for perforated and nonperforated appendicitis. RESULTS: Overall, a 16-ppb increase in the 7-day cumulative average daily maximum O3 concentration was associated with all appendicitis cases across the 12 cities (pooled OR = 1.07; 95% CI: 1.02, 1.13). The association was stronger among patients presenting with perforated appendicitis for the 7-day average (pooled OR = 1.22; 95% CI: 1.09, 1.36) when compared with the corresponding estimate for nonperforated appendicitis [7-day average (pooled OR = 1.02, 95% CI: 0.95, 1.09)]. Heterogeneity was not statistically significant across cities for either perforated or nonperforated appendicitis (p > 0.20). CONCLUSIONS: Higher levels of ambient O3 exposure may increase the risk of perforated appendicitis.