Food allergy and infant feeding practices: Are they related?

BACKGROUND: Immunoglobulin (Ig)E-mediated food allergy is a growing health problem affecting up to 10% of children. It is well-established that early introduction to peanuts and eggs from 4 months of age has a preventive effect. In contrast, there is no consensus about the effect of breastfeeding on food allergy development. OBJECTIVE: To evaluate the effect of breastfeeding and cows' milk formula (CMF) feeding on the development of IgE-mediated food allergy. METHODS: Infants in the Cow's Milk Early Exposure Trial were followed for 12 months. The cohort was divided according to parental feeding preferences for the first 2 months of life: group 1: exclusive breastfeeding (EBF); group 2: breastfeeding with at least 1 daily meal of CMF; and group 3: feeding with CMF only. RESULTS: Among a total of 1989 infants, 1071 were on EBF (53.8%), 616 were breastfed with addition of CMF (31%), and 302 were fed with CMF only (15.2%), from birth. By 12 months, 43 infants developed an IgE-mediated food allergy (2.2%); 31 in the EBF group (2.9%), 12 in the breastfeeding and CMF combined group (1.9%), and none in the CMF feeding-only group (P = .002). Family atopic comorbidity did not affect the results. CONCLUSION: In this prospective cohort, breastfed infants developed significantly higher rates of IgE-mediated food allergy during the first year of life. Perhaps the mechanism is related to compounds ingested by the mother and secreted in the breastmilk. Future larger cohorts should validate these results and offer the lactating mother recommendations. TRIAL REGISTRATION: The COMEET study and its derivatives were approved by the Ethics Committee of Meir Medical Center, IRB number 011-16-MMC. It was registered at the National Institutes of Health Clinical Trials Registry: NCT02785679.

Cow's milk allergy skin tests: fresh milk, commercial extracts, or both?

BACKGROUND: The diagnosis of food allergy is based on a history of immediate allergic reaction following food ingestion, and skin prick test (SPT) demonstrating sensitization with commercial extracts (CE) or fresh food (FF). For most food allergens, the SPT with FF is considered more accurate and predictive. Regarding cow's milk, the results are inconclusive. This retrospective study aimed to evaluate the accuracy of SPT with fresh milk compared to CE (cow's milk and casein) for evaluation of cow's milk allergy (CMA). METHODS: This study summarized the medical records of children, diagnosed with CMA. The data include demographics, skin tests and oral food challenge results, as well as atopic comorbidities. RESULTS: Records of 698 patients with the diagnosis of CMA were reviewed, 388 fulfilled the inclusion criteria. Overall, 134 patients (34.54%) had an additional atopic disease. The SPT wheal size with fresh milk was significantly larger than with CE (cow's milk and casein) at first evaluation or before oral food challenge (OFC). Combination of SPT results (CE and FF) gave the maximal odds ratio for reaction during OFC and SPT with fresh milk alone gave the minimal OR (34.18 and 4.74, respectively). CONCLUSIONS: SPT with CE for CMA evaluation is more reliable than SPT performed with fresh milk. In patients suspected of having IgE-mediated CMA, before deciding on performing OFC, it is advised to perform SPT with at least two different extracts, and always include casein. Fresh milk can serve as a backup if commercial extracts are not available. In cases that the SPT with fresh milk is 3 mm or less, there is 93.3% chance that the OFC will pass without reaction. Trial registration This study protocol was reviewed and approved by the Ethics Committee of Meir Medical Center, IRB Number 0083-18 MMC.

Chronic Urticaria in Elderly-New Insights.

BACKGROUND: Many medical conditions have a unique profile in older adults. Chronic urticaria (CU) is a common disease, but data regarding elderly patients are limited. OBJECTIVE: To describe the demographics, clinical characteristics, comorbidities, and outcome of elder patients with CU. METHODS: This retrospective, single-center study included patients older than 65 years, diagnosed with CU in our clinic. Data for the entire cohort were retrieved from electronic medical records. RESULTS: Of 1859 patients older than 65 years, 181 patients diagnosed with CU were included: 166 had chronic spontaneous urticaria (CSU) and 15 chronic inducible urticaria. Most patients with CSU were female (119, 72%). The mean age at diagnosis was 72 ± 5.9 years. Comorbidities included autoimmunity in 38 (22.9%), malignancy in 23 (13.8%), and atopy in 19 (11.5%). The time to referral to a specialist was 22.8 ± 53 months from the onset of symptoms. Specialist intervention improved patient outcomes. This was evident by reduced systemic steroid use (odds ratio [OR] = 0.145, [95% confidence interval (CI): 0.08-0.26], P < .001), all-cause hospitalization (OR = 0.09, [95% CI: 0.01-0.75], P = .01), emergency department visits (OR = 0.08, [95% CI: 0.08-0.35], P < .001), and primary physician visits (P < .001, Cramer's V = 0.528). CONCLUSIONS: Older people with CU have unique characteristics, including high prevalence of autoimmunity and malignancy and lower prevalence of atopy. Raising awareness of CU in elderly and prompt referral to an allergy specialist may improve outcomes.

Early, continuing exposure to cow's milk formula and cow's milk allergy: The COMEET study, a single center, prospective interventional study.

BACKGROUND: Cow's milk allergy (CMA) is a common food allergy among infants. Information regarding the best timing for first exposure to cow's milk formula (CMF) is controversial and more evidence is required. Few randomized control trials have tried to accurately assess the timing and preventive effect of exposure to CMF on small cohorts. OBJECTIVE: This study assessed the association between early, continuing exposure to CMF on the basis of the parents' preferences and the development of immunoglobulin E (IgE)-mediated CMA in a large birth cohort. METHODS: Newborns were prospectively recruited shortly before birth and divided into 2 groups according to parental feeding preference for the first 2 months of life: (1) exclusive breastfeeding (EBF); or (2) at least 1 meal of CMF (with or without breastfeeding) daily. Infants were followed up monthly until the age of 12 months. RESULTS: Among 1992 infants participating in the study, 1073 (53.86%) were in the EBF group until 2 months of age. IgE-mediated CMA was confirmed in 0.85% (n = 17); all were in the EBF group. Within this group, the prevalence of IgE-mediated CMA was 1.58% compared with 0 in the other groups (relative risk, 29.98; P < .001). Post hoc analysis revealed IgE-mediated CMA prevalence of 0.7% in the per-protocol EBF group vs 3.27% among breastfed infants who were exposed to a small amount of CMF during the first 2 months of life. A family atopic background did not affect the results. CONCLUSION: Early, continuing exposure to CMF from birth has the potential to prevent the development of IgE-mediated CMA and should be encouraged. However, the exposure needs to be consistent because occasional exposure increases the risk of developing IgE-mediated CMA and should be avoided.

The effect of asthma specialist intervention on asthma control among adults.

Background: Various ways to improve asthma control have been studied, with only a modest effect. Purpose: To evaluate the effect of asthma specialist visit on asthma control among adult asthma patients. Patients and methods: This matched cohort study included patients ages 21-50 with asthma and at least 1 visit to an asthma specialist. Patients were compared to adult asthma patients treated only by primary care physicians. The study outcomes, included use of asthma medication, healthcare visits, and mortality. All outcomes were compared one year before and after specialist visit. Results: 4166 pairs were included in the study. In the study group, a statistically significant decrease in the average number of relievers (1.5 ± 3.2 vs. 1.17 ± 2.9, p < 0.001) and systemic steroids purchased (0.53 ± 1.2 vs. 0.4 ± 1.2, p < 0.001), with an increase in average number of inhaled steroid purchased (1.6 ± 2.5 vs. 2.3 ± 33, p < 0.001) was seen over time. A significant decrease in the average number of PCP visits (9.5 ± 7.2 vs. 8.9 ± 7.3, p < 0.001), emergency department (ED) visits (0.46 ± 1 vs. 0.4 ± 0.9, p = 0.05) and all-cause hospitalization (0.03 ± 0.22 vs. 0.01 ± 1.9, p < 0.001) was seen in the study group but not in controls. Generalized linear modeling demonstrated an overall significant effect of specialist intervention for all parameters (p < 0.01), except ED visits (p = 0.06). During follow-up, eight (0.2%) study group patients vs. 19 (0.5%) controls died (p = 0.03). Conclusion: We found that asthma specialist intervention significantly improved asthma outcomes in adults. Referring adult asthma patients to an asthma specialist should be a goal of asthma management plans. Trial registration: Not relevant.

Changes in peripheral blood eosinophils may predict colorectal cancer - A retrospective study.

Background: Colorectal cancer (CRC) is a leading cause of morbidity and mortality worldwide. Eosinophils are traditionally associated and studied in context of allergic diseases. However, recent data implicate their involvement in mucosal tumors, especially in CRC where they may have an anti-tumorigenic function.Our objective was to evaluate whether trends in peripheral blood eosinophil numbers are associated with future diagnosis of CRC. Methods: This retrospective cohort study included adult patients diagnosed with CRC compared to matched controls. We evaluated the linear change in the absolute number of eosinophils (ANE) in peripheral blood over time, described as a correlation coefficient (r). The timeline started 7 years and ended 3 months before diagnosis of CRC. Results: We included 8334 CRC patient/control pairs. Over the study period, no linear correlation was found between levels of eosinophils and time in either group. In a subset of patients (1350, 8.1%), a positive linear correlation was found between levels of eosinophils and time. CRC was significantly more common in these patients (59% vs. 41%, p < 0.01). In a logistic regression, positive r was found to be an independent predictor for CRC (OR 1.31, 95%CI: 1.22-1.41, p < 0.001) with high specificity (0.93) but low sensitivity (0.1). Conclusion: We found higher risk for CRC in patients with a positive linear increase in peripheral eosinophils over time. This may be an indirect clue that eosinophils play a role in the pathogenesis of CRC. Linear changes in ANE may be used in the future to improve screening measures for CRC. Trial registration: Not relevant.

Humoral Response to Hepatitis B and COVID-19 Vaccine among Maintenance Hemodialysis Patients.

Maintenance hemodialysis (MHD) patients have impaired immunological responses to pathogens and vaccines. In this study, we compared the humoral response to HBV and COVID-19 vaccines in a cohort of MHD patients. Demographic and clinical characteristics of vaccine responders and non-responders were also compared, and the association between the humoral responses to both vaccines was evaluated. The cohort included 94 MHD patients who were vaccinated at least once for HBV and twice for COVID-19. Among the 94 patients, 28 (29.8%) did not develop protective titers to HBV. Hypertension, coronary heart disease, and heart failure were more common in non-responders. Among MHD patients, 85% had positive IgG anti-spike SARS-CoV-2 levels 6 months after two doses of BNT162b2 (Pfizer/Biotech) vaccine. Age and immunosuppressive therapy were the main predictors of humoral response to COVID-19 vaccine. We did not find any association between non-responders to HBV and non-responders to COVID-19 vaccine. There was no difference in IgG anti-spike titers between HBV responders and non-responders (505 ± 644 vs. 504 ± 781, p = 0.9) Our results suggest that reduced humoral response to hepatitis B is not associated with reduced response to COVID-19 vaccine. Different risk-factors were associated with poor immune response to HBV and to COVID-19 vaccines.

Endoscopic Inferior Meatal Antrostomy for Antrochoanal Polyps: A Long-Term Follow-Up.

BACKGROUND: Endoscopic middle meatal antrostomy (EMMA) is considered the standard approach for surgical management of antrochoanal polyps (ACPs). Recently, an endoscopic inferior meatal antrostomy (EIMA) approach for clearing lesions in the maxillary sinus was described. In this study, we compared the long-term outcome of patients with ACP following surgical treatment using one of these 2 approaches (EIMA or EMMA). METHODS: The medical charts of all patients treated for ACPs in our institution between January 1, 2009, and July 1, 2020, were reviewed retrospectively. Patients were invited to complete a long-term follow-up assessment. RESULTS: Thirty-eight patients were included in the study: EIMA was the only procedure performed in 25 patients (66%) and EMMA was the only procedure performed in 7 patients (18%). Both procedures were performed in 6 patients (16%): 2 patients (5%) underwent simultaneous EMMA and EIMA for better access and visualization and 4 patients (10.5%) underwent surgical revision consisting of EIMA secondary to failed EMMA at other institutions. Median follow-up was 44 months (range, 6 months-11 years). No evidence of recurrent ACPs, recirculation, synechiae, nasolacrimal duct injury, or bleeding was observed in any of our patients. Small nonobstructing cysts were observed in 2 patients (8%) following EIMA. CONCLUSIONS: EIMA prevents violation of the ostiomeatal complex. It provides access to the anteroinferior aspect of the maxillary sinus and should be considered as an alternative to EMMA in patients with ACPs.

Nivolumab-induced diffuse type 2 rhinosinusitis: A case report.

BACKGROUND: Nivolumab, an immune checkpoint inhibitor is used to treat advanced metastatic malignancies. Data showed that nivolumab can cause exacerbated response of T-Helper 2 cells and lead to airway inflammation. OBJECTIVE: To present the upper airway findings of a 69-year-old woman after treatment with nivolumab. METHODS: Case report. RESULTS: A 69-year old woman with no history of chronic rhinosinusitis developed complaints of nasal congestion, rhinorrhea, sneezing, and anosmia. These symptoms started after one year of treatment with nivolumab. Pale polyps were observed on fiberoptic endoscopy examination. A gradual increase in eosinophil blood counts was noted. On histopathology, heavy infiltrates of eosinophils were seen in the tissue. CONCLUSIONS: Nivolumab is used to treat various advanced metastatic malignancies, with a good safety profile. Nevertheless, physicians must be alert to the possibility of evolving type II inflammation in patients, as appropriate therapy can be provided to improve their quality of life.

Childhood Asthma - The Effect of Asthma Specialist Intervention on Asthma Control: A Retrospective Review.

BACKGROUND: Childhood asthma is the most common chronic disease throughout the western world. Improving asthma control is a leading health management goal. PURPOSE: To evaluate the effect of an intervention by a visit to an asthma specialist on asthma control in children. MATERIALS AND METHODS: This retrospective study was conducted using the electronic database of Maccabi Health Services. All members ages 5-16 with an asthma diagnosis during 2000-2016, and at least one visit to a specialist were included. Asthma outcomes during the 2 years before and after the visit to the asthma specialist were compared. RESULTS: A total of 37,066 children were diagnosed with asthma. Among them, 13,533 (36.5%) had at least one visit to an asthma specialist and were included. Children with asthma visited their primary care physician more often in the period before the specialist visit (4.4± 4.4 vs 3.16± 3.9 visits, respectively; p<0.01). After visiting a specialist, average number of visits to emergency departments (0.52± 1.3 vs 0.45±1), all cause hospitalizations (0.13±0.45 vs 0.08±0.4) and hospitalizations due to asthma exacerbations (0.08±0.345 vs 0.05±0.3) decreased (p<0.01 for all comparisons). Prescription of short-acting beta agonists decreased (2.85±3.6 vs 2.2 ±3.7, p<0.01) and inhaled steroid prescriptions increased (1.9±2.9 vs 2.7±3.7, p<0.01), respectively, after the intervention. A substantial reduction in the prescription of corticosteroids (0.81±1.9 vs 0.43±1.4, p<0.01) after specialist visit was also noted. CONCLUSION: We found significant positive outcomes after a single consultation with an asthma specialist. Referring pediatric asthma patients to an asthma specialist should be one of the goals of an asthma management plan.

Young Adults with Mild Asthma in a High-Risk Occupation: Incidence and Risk Factors for Exacerbation.

BACKGROUND: The effects of high-risk environment on young adults with mild asthma were never fully tested in practice, as most high-risk occupations do not welcome them. This study examines the effect of combat training on asthma worsening in the Israeli Defense Forces. METHODS: Persons with asthma in remission and mild intermittent asthma who underwent combat training between 2014 and 2017 were compared in terms of disease worsening to their counterparts performing clerical duties during a follow-up of 8 months. Among combat trainees, exposure to known triggers for asthma exacerbation and health status on enlistment were assessed as risk factors for asthma exacerbation. RESULTS: Asthma worsening among persons with asthma in remission was twice as common among those who are undergoing training compared to persons performing clerical duties. This difference was smaller among mild intermittent asthmatics. For both asthma severities, rates of asthma exacerbation requiring emergency room treatment were several times higher among the training group. Among individuals undergoing training, mild intermittent asthma was a significant risk factor for asthma worsening compared to asthma in remission (OR 1.99 [1.44-2.75]) while age (OR 0.67 [0.53-0.85]) and immigration to Israel (OR 0.55 [0.31-0.95]) were significant protective factors. INTERPRETATION: Young adults with mild asthma are at significant risk for severe exacerbations when exposed to high-risk environment even among individuals who have long been symptom free. No single risk factor was found to have an independent effect suggesting a synergistic mechanism that is harder to mitigate.

Clinical history in suspected cases of immediate allergy to beta-lactam.

BACKGROUND: Mislabeling patients as allergic to beta lactams poses an increased risk of morbidity, healthcare costs, and even mortality. This study aimed to define the accuracy of medical history, taken by a specialist, in diagnosing immediate reaction to beta lactams. METHODS: All patients labeled as allergic to beta lactam were interviewed by a specialist in allergy and clinical immunology and defined as suspected of having a history of immediate or non-immediate reaction. When indicated, skin tests to major and minor determinants and oral graded challenge to the culprit drug were performed. RESULTS: A total of 909 patients were evaluated. A total of 798 (87.7%) were labeled as allergic to penicillin. In 108 (11.9%) cases, the allergist suspected an immediate reaction based on clinical history. Skin test or challenge proven diagnosis of IgE-mediated allergy to beta lactam were significantly more prevalent in the group with an allergist's suspicion of an immediate allergy (23.1% vs. 5%, p < 0.01). The sensitivity and negative predictive values of an anamnesis of immediate reaction were high (0.9 and 0.95, respectively), but the specificity and positive predictive value were low (0.37 and 0.23, respectively). CONCLUSION: Medical history taken by an allergist can exclude immediate hypersensitivity reaction, but it is not specific enough to confirm the diagnosis. Skin testing and graded challenge in suspected cases of immediate hypersensitivity reaction are indicated.

Chronic urticaria in children - New insights from a large cohort.

BACKGROUND: Chronic spontaneous urticaria is well-described in adults, but less so in children. The aim of this study is to describe the demographics, clinical characteristics, comorbidities, and outcomes of children with chronic, spontaneous urticaria. METHODS: This retrospective study followed children up to 18 years old, diagnosed with chronic spontaneous urticaria, between the years 2002-2018, and treated in a tertiary referral allergy and clinical immunology center. Data including demographics, clinical characteristics, comorbidities, treatments, and outcomes were extracted from electronic medical records. RESULTS: Records of 380 children coded to have chronic urticaria were reviewed, of which 250 (65.8%) fulfilled the diagnostic criteria for chronic spontaneous urticaria. There were 136 females (54.4%). Mean age at diagnosis was 11.4 years, and 122 (48%) were adolescents. The average duration of chronic spontaneous urticaria was 12.25 ± 15.2 months. The urticaria in 208 children )83.2%) resolved within 24 months. Eighty-seven patients (34.8%) had at least one atopic disease. Atopic comorbidities included atopic dermatitis in 17.2%, allergic rhinitis in 16%, asthma in 13.2%, and food allergy in 3.2%. Eighteen patients (7.2%) had a concomitant autoimmune disease. Nine (3.6%) had thyroid disease. CONCLUSIONS AND CLINICAL RELEVANCE: Chronic spontaneous urticaria in children is a self-limited disease with favorable prognosis. Atopic diseases are more prevalent in children with chronic spontaneous urticaria than in the general pediatric population, increasing the possibility of a special subgroup of TH2-related chronic urticaria in children.

Intubation using the gum-elastic bougie while wearing personal protective equipment.

OBJECTIVE: To determine whether application of a gum-elastic bougie (GEB), a visual stylet used to improve success rates of difficult intubations, reduces the time, and number of attempts to achieve successful intubation while wearing personal protective equipment (PPE). DESIGN: A randomized cross-over study comparing orotracheal intubations performed on an AirMan® Mannequin, using either a semirigid stylet or a GEB, while wearing an active hood with a charcoal impregnated suit and butyl rubber gloves. SETTING: Simulation training field of the Israel Defense Force Medical Corps. PARTICIPANTS: 27 military physicians and 23 paramedics (PMs). INTERVENTIONS: Comparing intubation with and without using the GEB while wearing PPE. MAIN OUTCOME MEASURE(S): Airway (AW) control was considered successful if the "lungs" of the mannequin ex-panded during bag ventilation. Three unsuccessful attempts or a procedure exceeding 60 seconds were regarded as a failure. Correlations between parameters of self-assessment of skills and successful intubation were also determined. RESULTS: With the GEB, success rate was lower (82 percent versus 100 percent, p = 0.002), more attempts were needed (1.4 ± 0.7 versus 1.0 ± 0.2, p = 0.005) and time-to-achieve AW control was longer (43.6 ± 14.6 sec-onds versus 23.1 ± 10.5 seconds, P < 0.001) than without it. Participants with high self-assessment of GEB-assisted AW management skills needed less attempts to perform successful intubation with GEB than participants with low self-assessment (1.0 ± 0.0 versus 1.4 ± 0.8, p = 0.001), but not less time to achieve it. CONCLUSIONS: While donning PPE, the use of GEB (versus semirigid stylets) did not reduce the time or the number of attempts necessary to achieve successful intubation.

Midazolam and isoflurane combination reduces late brain damage in the paraoxon-induced status epilepticus rat model.

Organophosphates (OPs) are widely used as pesticides and have been employed as warfare agents. OPs inhibit acetylcholinesterase, leading to over-stimulation of cholinergic synapses and can cause status epilepticus (SE). OPs poisoning can result in irreversible brain damage and death. Despite termination of SE, recurrent seizures and abnormal brain activity remain common sequelae often associated with long-term neural damage and cognitive dysfunction. Therefore, early treatment for prevention of seizures is of high interest. Using a rat model of paraoxon poisoning, we tested the efficacy of different neuroprotective and anti-epileptic drugs (AEDs) in suppressing early seizures and preventing brain damage. Electrocorticographic recordings were performed prior, during and after injection of 4.5 LD50 paraoxon, followed by injections of atropine and toxogonin (obidoxime) to prevent death. Thirty minutes later, rats were injected with midazolam alone or in combination with different AEDs (lorazepam, valproic acid, phenytoin) or neuroprotective drugs (losartan, isoflurane). Outcome measures included SE duration, early seizures frequency and epileptiform activity duration in the first 24 -hs after poisoning. To assess delayed brain damage, we performed T2-weighted magnetic resonance imaging one month after poisoning. SE duration and the number of recurrent seizures were not affected by the addition of any of the drugs tested. Delayed brain injury was most prominent in the septum, striatum, amygdala and piriform network. Only isoflurane anesthesia significantly reduced brain damage. We show that acute treatment with isoflurane, but not AEDs, reduces brain damage following SE. This may offer a new therapeutic approach for exposed individuals.

Exclusive Bee Venom Allergy: Risk Factors and Outcome of Immunotherapy.

INTRODUCTION: Venom immunotherapy (VIT) is considered to be the gold-standard treatment for patients with Hymenoptera venom allergy. Data regarding VIT in bee venom (BV) allergic patients are scarce. AIM: The aim of this study was to evaluate the outcome of VIT in patients with exclusive BV allergy and to try to define risk factors for VIT-induced systemic reactions (VIT-ISR) and VIT failure. METHODS: This is a retrospective study including data from all BV allergic patients that were treated by VIT in the Allergy Unit at the Meir Medical Center in the years 1995-2018. RESULTS: Two hundred and forty-seven patients with exclusive BV allergy were included; 206 (83.4%) preferred to undergo rush buildup. Sixty-nine patients (27.9%) had at least 1 reaction during buildup, with the c-kit mutation being the only significant risk factor (100 vs. 28.9%, p = 0.02). Female gender (25.4 vs. 13.3%, p = 0.04), conventional buildup schedule (26.8 vs. 14.1%, p = 0.04), and c-kit mutation (100 vs. 16.8%, p < 0.01) but not tryptase level were found to be significantly more frequent in recurrent reactors. Females (20.3 vs. 9%, p = 0.03), patients with severe systemic reaction to the index sting (24.3 vs. 9.5%, p = 0.004), and c-kit mutation (66 vs. 12%, p = 0.05) but not tryptase level were found to be risk factors for severe systemic reactions. CONCLUSION: Despite the considerably high rate of VIT-ISR in patients with exclusive BV allergy, VIT can be performed safely and efficiently. C-kit mutation, and not basal serum tryptase level, seems to be a preferable biomarker for VIT-ISR in these patients.

Characterization of chronic urticaria and associated conditions in a large population of adolescents.

BACKGROUND: Although chronic spontaneous urticaria (CSU) affects all age groups, data regarding CSU in adolescents is scarce. OBJECTIVE: To characterize the epidemiology, demographics, and comorbidities associated with CSU in a large, cross-sectional nationwide population of adolescents. METHODS: Medical records of 16-year-old candidate conscripts to the Israeli Defense Forces were reviewed. Data were collected on the prevalence and severity of CSU, as well as the demographics, medical comorbidities, medication use, and blood test results of affected individuals. RESULTS: Medical records of 1,108,833 consecutive 16-year-old adolescents were reviewed. A total of 6617 (0.6%) adolescents received CSU diagnoses. CSU was increased in female conscripts (odds ratio [OR] 1.13, 95% confidence interval [CI] 1.07-1.19, P < .001) and adolescents with higher socioeconomic scores (OR 1.92, 95% CI 1.56-2.32, P < .001). Individuals with CSU were significantly more likely to have allergic diseases, including food allergy (OR 7.31, 95% CI 6.13-8.72), allergic rhinitis (OR 2.9, 95% CI 2.71-3.11), atopic dermatitis (OR 2.35, 95% CI 2.03-2.72), and asthma (OR 1.46, CI 1.35-1.57). CONCLUSION: Our work provides an account of CSU in a large cohort of adolescents. We found a strong link between CSU and atopic diseases. Further investigation is needed to decipher the mechanism underlying this observed association.