Cold-induced urticaria in children: A multicenter, retrospective cohort study.

Background: Studies of cold-induced urticaria (ColdU) in pediatric patients are limited and not well characterized. Objective: The objective of the study was to investigate the characteristics of ColdU in children. Methods: A multicenter, retrospective chart review was performed in children ages ≤18 years diagnosed with ColdU at 11 pediatric allergy and immunology centers in Turkey between September 1, 2010, and August 31, 2022. Results: A total of 83 children with ColdU were included, 54.2% were girls, and the mean age of symptom onset was 8.8 years. The median duration of ColdU at the time of diagnosis was significantly higher in the girls than in the boys (1.0 years [0.0-13.8 years] versus 0.3 years [0.0-15.0 years]; p = 0.007). All the patients underwent an ice cube test, and 71.1% were found positive (typical ColdU). The mean ± standard deviation age of onset was significantly higher in the patients with typical ColdU versus atypical patients (9.4 ± 4.5 years versus 7.3 ± 4.5 years; p = 0.041). Swimming alone and in combination with the wind were significantly the most reported triggers in patients with cold-induced anaphylaxis (ColdA) when compared with patients with ColdU and with nonanaphylactic symptoms (70.0% versus 28.9% [p = 0.022], and 50.0% versus 4.1% [p < 0.001], respectively). Only patients with other chronic urticaria were found to be associated with the development of typical ColdU (p = 0.036). The median total serum immunoglobulin E (IgE) was significantly higher in typical ColdU than in atypical patients (72.5 IU/mL [3.86 - 2500 IU/mL] versus 30.0 IU/mL [0.83 - 1215 IU/mL]; p = 0.007); however, total serum IgE differences were not found to affect ColdU resolution between the two groups (p = 0.204). The resolution was documented in 30.4%. Conclusion: Those who were boys and had a positive ice cube test result could have an association with earlier onset of ColdU. Those swimming alone on a windy day were at highest risk for ColdA. It is still unclear what characteristics are associated with the resolution of ColdU, and this warrants further investigation.

Recent developments in the immunopathology of COVID-19.

There has been an important change in the clinical characteristics and immune profile of Coronavirus disease 2019 (COVID-19) patients during the pandemic thanks to the extensive vaccination programs. Here, we highlight recent studies on COVID-19, from the clinical and immunological characteristics to the protective and risk factors for severity and mortality of COVID-19. The efficacy of the COVID-19 vaccines and potential allergic reactions after administration are also discussed. The occurrence of new variants of concerns such as Omicron BA.2, BA.4, and BA.5 and the global administration of COVID-19 vaccines have changed the clinical scenario of COVID-19. Multisystem inflammatory syndrome in children (MIS-C) may cause severe and heterogeneous disease but with a lower mortality rate. Perturbations in immunity of T cells, B cells, and mast cells, as well as autoantibodies and metabolic reprogramming may contribute to the long-term symptoms of COVID-19. There is conflicting evidence about whether atopic diseases, such as allergic asthma and rhinitis, are associated with a lower susceptibility and better outcomes of COVID-19. At the beginning of pandemic, the European Academy of Allergy and Clinical Immunology (EAACI) developed guidelines that provided timely information for the management of allergic diseases and preventive measures to reduce transmission in the allergic clinics. The global distribution of COVID-19 vaccines and emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with reduced pathogenic potential dramatically decreased the morbidity, severity, and mortality of COVID-19. Nevertheless, breakthrough infection remains a challenge for disease control. Hypersensitivity reactions (HSR) to COVID-19 vaccines are low compared to other vaccines, and these were addressed in EAACI statements that provided indications for the management of allergic reactions, including anaphylaxis to COVID-19 vaccines. We have gained a depth knowledge and experience in the over 2 years since the start of the pandemic, and yet a full eradication of SARS-CoV-2 is not on the horizon. Novel strategies are warranted to prevent severe disease in high-risk groups, the development of MIS-C and long COVID-19.

Recent advances and developments in COVID-19 in the context of allergic diseases.

BACKGROUND: Since the first reports of coronavirus disease 2019 (COVID-19) in Wuhan, China, in December 2019, there have been 198 million confirmed cases worldwide as of August 2021. The scientific community has joined efforts to gain knowledge of the newly emerged virus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the immunopathological mechanisms leading to COVID-19, and its significance for patients with allergies and asthma. METHODS: Based on the current literature, recent advances and developments in COVID-19 in the context of allergic diseases were reviewed. RESULTS AND CONCLUSIONS: In this review, we discuss the prevalence of COVID-19 in subjects with asthma, attacks of hereditary angioedema, and other allergic diseases during COVID-19. Underlying mechanisms suggest a protective role of allergy in COVID-19, involving eosinophilia, SARS-CoV-2 receptors expression, interferon responses, and other immunological events, but further studies are needed to fully understand those associations. There has been significant progress in disease evaluation and management of COVID-19, and allergy care should continue during the COVID-19 pandemic. The European Academy of Allergy & Clinical Immunology (EAACI) launched a series of statements and position papers providing recommendations on the organization of the allergy clinic, handling of allergen immunotherapy, asthma, drug hypersensitivity, allergic rhinitis, and other allergic diseases. Treatment of allergies using biologics during the COVID-19 pandemic has also been discussed. Allergic reactions to the COVID-19 vaccines, including severe anaphylaxis, have been reported. Vaccination is a prophylactic strategy that can lead to a significant reduction in the mortality and morbidity associated with SARS-CoV-2 infection, and in this review, we discuss the proposed culprit components causing rare adverse reactions and recommendations to mitigate the risk of anaphylactic events during the administration of the vaccines.

Risk factors for severe and critically ill COVID-19 patients: A review.

The pandemic of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused an unprecedented global social and economic impact, and high numbers of deaths. Many risk factors have been identified in the progression of COVID-19 into a severe and critical stage, including old age, male gender, underlying comorbidities such as hypertension, diabetes, obesity, chronic lung diseases, heart, liver and kidney diseases, tumors, clinically apparent immunodeficiencies, local immunodeficiencies, such as early type I interferon secretion capacity, and pregnancy. Possible complications include acute kidney injury, coagulation disorders, thoromboembolism. The development of lymphopenia and eosinopenia are laboratory indicators of COVID-19. Laboratory parameters to monitor disease progression include lactate dehydrogenase, procalcitonin, high-sensitivity C-reactive protein, proinflammatory cytokines such as interleukin (IL)-6, IL-1ß, Krebs von den Lungen-6 (KL-6), and ferritin. The development of a cytokine storm and extensive chest computed tomography imaging patterns are indicators of a severe disease. In addition, socioeconomic status, diet, lifestyle, geographical differences, ethnicity, exposed viral load, day of initiation of treatment, and quality of health care have been reported to influence individual outcomes. In this review, we highlight the scientific evidence on the risk factors of severity of COVID-19.

A compendium answering 150 questions on COVID-19 and SARS-CoV-2.

In December 2019, China reported the first cases of the coronavirus disease 2019 (COVID-19). This disease, caused by the severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2), has developed into a pandemic. To date, it has resulted in ~9 million confirmed cases and caused almost 500 000 related deaths worldwide. Unequivocally, the COVID-19 pandemic is the gravest health and socioeconomic crisis of our time. In this context, numerous questions have emerged in demand of basic scientific information and evidence-based medical advice on SARS-CoV-2 and COVID-19. Although the majority of the patients show a very mild, self-limiting viral respiratory disease, many clinical manifestations in severe patients are unique to COVID-19, such as severe lymphopenia and eosinopenia, extensive pneumonia, a "cytokine storm" leading to acute respiratory distress syndrome, endothelitis, thromboembolic complications, and multiorgan failure. The epidemiologic features of COVID-19 are distinctive and have changed throughout the pandemic. Vaccine and drug development studies and clinical trials are rapidly growing at an unprecedented speed. However, basic and clinical research on COVID-19-related topics should be based on more coordinated high-quality studies. This paper answers pressing questions, formulated by young clinicians and scientists, on SARS-CoV-2, COVID-19, and allergy, focusing on the following topics: virology, immunology, diagnosis, management of patients with allergic disease and asthma, treatment, clinical trials, drug discovery, vaccine development, and epidemiology. A total of 150 questions were answered by experts in the field providing a comprehensive and practical overview of COVID-19 and allergic disease.

Immune response to SARS-CoV-2 and mechanisms of immunopathological changes in COVID-19.

As a zoonotic disease that has already spread globally to several million human beings and possibly to domestic and wild animals, eradication of coronavirus disease 2019 (COVID-19) appears practically impossible. There is a pressing need to improve our understanding of the immunology of this disease to contain the pandemic by developing vaccines and medicines for the prevention and treatment of patients. In this review, we aim to improve our understanding on the immune response and immunopathological changes in patients linked to deteriorating clinical conditions such as cytokine storm, acute respiratory distress syndrome, autopsy findings and changes in acute-phase reactants, and serum biochemistry in COVID-19. Similar to many other viral infections, asymptomatic disease is present in a significant but currently unknown fraction of the affected individuals. In the majority of the patients, a 1-week, self-limiting viral respiratory disease typically occurs, which ends with the development of neutralizing antiviral T cell and antibody immunity. The IgM-, IgA-, and IgG-type virus-specific antibodies levels are important measurements to predict population immunity against this disease and whether cross-reactivity with other coronaviruses is taking place. High viral load during the first infection and repeated exposure to virus especially in healthcare workers can be an important factor for severity of disease. It should be noted that many aspects of severe patients are unique to COVID-19 and are rarely observed in other respiratory viral infections, such as severe lymphopenia and eosinopenia, extensive pneumonia and lung tissue damage, a cytokine storm leading to acute respiratory distress syndrome, and multiorgan failure. Lymphopenia causes a defect in antiviral and immune regulatory immunity. At the same time, a cytokine storm starts with extensive activation of cytokine-secreting cells with innate and adaptive immune mechanisms both of which contribute to a poor prognosis. Elevated levels of acute-phase reactants and lymphopenia are early predictors of high disease severity. Prevention of development to severe disease, cytokine storm, acute respiratory distress syndrome, and novel approaches to prevent their development will be main routes for future research areas. As we learn to live amidst the virus, understanding the immunology of the disease can assist in containing the pandemic and in developing vaccines and medicines to prevent and treat individual patients.

The Etiology and Clinical Features of Anaphylaxis in a developing country: A nationwide survey in Turkey.

BACKGROUND: Despite the increasing frequency of anaphylaxis, there is inadequate information on the etiology and clinical features in various countries, regions and age groups, especially in developing countries. OBJECTIVE: Our aim is to assess the etiology and clinical findings of anaphylaxis in Turkey. Gathering reliable data about the etiology and clinical findings of anaphylaxis in the general population will decrease the related morbidity and mortality. METHOD: We obtained the names and phone numbers of individuals who had been prescribed an epinephrine auto-injector with a diagnosis of anaphylaxis from ministry of health. Demographic data, clinical history of the first episode of anaphylaxis including the triggering agent, clinical findings, course of hospitalization, and the management of anaphylaxis were obtained by phone survey. RESULTS: A total of 843 patients with a mean age of 21.4±17.3 years were evaluated. There was a significant male predominance among children younger than 10 years of age but a female predominance in older subjects. The most common causes of anaphylaxis were foods(40.1%) in children and bee venom(60.8%) in adults. The biphasic reaction rate was 4.3% and the median length of stay at an emergency department was 4.0 hours. Almost 60% of the patients had recurrent anaphylaxis episodes. Only 10.7% of the cases were prescribed an epinephrine auto-injector at their first anaphylaxis episode and only 59.2% of the patients were referred to an allergist during discharge from the emergency department. CONCLUSIONS: In Turkey, bee venom was the most common cause of anaphylaxis, followed by food and drug. While more than a half of patients reported recurrent attacks; only 10% had been prescribed epinephrine auto-injector kit after their first episode. Strategies to improve the anaphyalxis management are therefore urgently required.

Clinical and etiologic evaluation of the children with chronic urticaria.

BACKGROUND: Chronic urticaria (CU) is a skin disorder defined as daily or almost daily exhibition of pruritic and transient wheals that last for 6 weeks. CU is divided into two subtypes: chronic spontaneous urticaria (CSU) and chronic inducible urticaria (CIndU). OBJECTIVES: To evaluate the clinical features, possible causes, associated findings, and laboratory results of different subtypes of CU in children according to a new classification. METHODS: In this study, we evaluated the clinical features, laboratory investigations, and provocation tests of children with different subtypes of CU according to a new classification. RESULTS: Two hundred and twenty-two children (59.9% girls) were enrolled in the study. Of the study patients, 59.9% and 40.1% were diagnosed as having CSU and CIndU, respectively. Antithyroid antibody levels were positive in 7.1% of the patients with CSU, 32.8% of the children had positive 14C-urea breath test results, and 6.5% of the patients had positive stool examination results for parasites. Autologous serum skin test results were positive in 53.5% of the patients with CSU. Of the patients with CIndU, 77.5% had symptomatic dermographism, 16.8% had cold urticaria, 2.2% had cholinergic urticaria, 2.2% had solar urticaria, and 1.1% had aquagenic urticaria. CONCLUSION: Children with CSU represent the majority of patients with CU, and more than a half of these patients might have autoimmune urticaria. Symptomatic dermographism was the most common type of CIndU.

IgE-Mediated Hypersensitivity and Desensitisation with Recombinant Enzymes in Pompe Disease and Type I and Type VI Mucopolysaccharidosis.

Enzyme replacement therapy (ERT) is important for the treatment of lysosomal storage disorders. Hypersensitivity reactions with ERT have been reported, and in these cases, desensitisation with the enzyme is necessary. Here we report the cases of 3 patients with lysosomal storage disorders, including Pompe disease and mucopolysaccharidosis type I and VI, who had IgE-mediated hypersensitivity reactions and positive skin tests. Successful desensitisation protocols with the culprit enzyme solution were used for these patients. All 3 patients were able to safely receive ERT with the desensitisation protocol.

The patterns and clinical relevance of contact allergen sensitization in a pediatric population with atopic dermatitis.

BACKGROUND/AIM: Data about contact allergen sensitization (CAS) in children with atopic dermatitis (AD) are limited. The purpose of this study was to identify the frequency and patterns of CAS in children with AD by using a ready-to-use patch test system. MATERIALS AND METHODS: After receiving the history of CAS in the patients, the severity of AD and IgE-mediated allergen sensitization were determined. RESULTS: Of 134 children with AD, 33.8% (n = 45) had at least 1 positive reaction. The most frequent positive reaction was to nickel sulfate (NS) (37.8%, 17/45), followed by methylchloroisothiazolinone (20.0%, 9/45) and thimerosal (15.6%, 7/45). The total Scoring Atopic Dermatitis (SCORAD) score was significantly higher in the NS-sensitized group (P = 0.036). The patients with NS sensitization had moderate-severe AD more frequently than those without any reaction (P = 0.020). When the SCORAD score was evaluated in detail, extent of eczema, score of sleep loss, and pruritus were significantly higher in the patients with NS sensitization than those without any reaction (P = 0.002, P = 0.001, and P = 0.002, respectively). CONCLUSION: Our study confirms the necessity of CAS in the management of AD. In particular, NS sensitization should be considered for children with severe AD or larger extent of eczema and trunk involvement.

Risk factors of severe atopic dermatitis in childhood: single-center experience.

The aim of this study was to evaluate the risk factors of disease severity to facilitate better management of children with severe atopic dermatitis (AD). All the patients were diagnosed using Hanifin-Rajka criteria. After medical and family histories were obtained and a detailed physical examination was performed, disease severity was determined with the objective SCORing Atopic Dermatitis (SCORAD) index. Skin prick tests were performed, and percent of peripheral blood eosinophils, total serum IgE and specific IgE were measured. The median age of the 501 patients was 15 months (interquartile range [IQR]: 6-40 months), and 62.9% (315) were male. Sensitization to at least one allergen and foods was observed in 40.3% (202) and 30.9% (155) of all patients, respectively. Of the study group, 17.6% (88) had severe disease. When logistic regression analyses were performed, with adjustments, the risk factors for severe AD were determined to be eosinophilia (odds ratio [OR] 1.137, 95% confidence interval [CI] 1.062-1.217; p=0.003) and food allergen sensitization (OR: 1.937, 95%CI: 1.217-3.084; p=0.005). The patients with severe AD had sensitization to common allergens, food allergens and eosinophilia more frequently than those with mild-moderate disease (p=0.001, p=0.001 and p=0.005, respectively). Eosinophilia may predict severe disease and allergic sensitization. Further large-scale follow-up studies are needed to improve the reliability and relevance of this relation.

Initial white blood cell kinetics for assessment of individual response to the conditioning regimen in pediatric hematopoietic stem cell transplantation patients.

We hypothesized that the individual hematological response to chemo/ radiotherapy may be used as a parameter to assess the degree of myeloablation and probability of transplant-related events. This study included 58 pediatric patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT). White blood cell (WBC) ratio (pre-conditioning WBC: day 0 WBC), day 0 WBC count, and WBC nadir day were used as potential indicators of myeloablation. The association between WBC kinetics and clinical result of HSCT was investigated. There was a positive correlation between WBC ratio and the date of engraftment. A positive correlation was noted between day 0 WBC count and engraftment day. There was a negative correlation between WBC nadir day and engraftment day. WBC nadir day was lower in patients with acute graft-versus-host disease (GVHD) than in cases without acute GVHD. Among patients who had fever during the conditioning regimen, the WBC ratio was higher, day 0 WBC count was lower, and WBC nadir day was lower in patients who developed >5 days of fever between day 0 and day +30. The present preliminary study suggests that WBC kinetics may be used as a measure of initial hematological response to the conditioning regimen and perhaps in determining the degree of myeloablation.

The evaluation of drug provocation tests in pediatric allergy clinic: a single center experience.

Drug provocation tests (DPTs) are gold standard to diagnose drug allergy. Our goal was to evaluate the results and safety of diagnostic methods including DPTs during childhood. Between January 2010 and February 2013 DPTs were performed and evaluated, prospectively, in children who attended our pediatric allergy clinic with a suspected drug hypersensitivity reaction. One hundred ninety-eight suspected drug reactions in 175 patients (88 boys and 87 girls) were evaluated. The median age of the subjects at the time of the suspected drug-induced hypersensitivity reaction and at the time of the study was 56 (interquartile range [IQR] = 24-120 months) months and 76 (IQR = 35-149 months) months, respectively. Suspected drugs were beta-lactam antibiotics in 108 cases (54.5%), non-beta-lactam antibiotics in 22 cases (11.1%), and nonsteroid anti-inflammatory drugs in 52 cases (26.3%). The history was compatible with immediate-type reactions in 69 cases (34.8%). Skin-prick tests were not positive in any of the cases. Intradermal tests were positive in three cases (4%). DPTs were positive in 13 (6.8%) of 191 provocation cases, which were performed with culprit drugs. Our results suggest that a positive clinical history is not enough to make a diagnosis of drug allergy, which highlights the significance of undertaking further diagnostic evaluation especially for DPTs.

What a pandemic teaches us about vaccination attitudes of parents of children with asthma.

BACKGROUND: During the recent pandemic, Influenza A/H1N1 vaccine uptake remained far below the targeted rates. Associated factors regarding vaccine refusal in the general population have been reported in many studies, however the reasons behind refusals for asthmatic children have not yet been identified. We aimed to investigate Influenza A/H1N1 virus vaccine acceptance for children with asthma, to determine the attitudes and beliefs of parents concerning Influenza A/H1N1 disease and vaccine and to identify the association of asthma control parameters with vaccination. METHODS: The parents of asthmatic children aged 6-18 years participated in a cross-sectional survey study in three pediatric allergy outpatient clinics. The survey measured demographic factors, asthma control parameters, vaccination rates, and beliefs and attitudes regarding Influenza A/H1N1 vaccine. RESULTS: Of the 625 asthmatic children, 16.8% (n=105) were immunized with Influenza A/H1N1 and 45.7% (n=286) with seasonal influenza vaccine. Educational background of parents (p<0.001 and p=0.002, for father's and mother's educational level, respectively), previous vaccination with seasonal influenza (p<0.001), and having a family member vaccinated against Influenza A/H1N1 (p<0.001) had a significant influence on vaccine acceptance, while fear of side effects (88.6%) was the major parental reason for refusing the vaccine. Asthma control parameters had no influence on uptake of the vaccine. Physician recommendation (84.8%) was important in the decision-making process for immunization. The statement "Children with asthma should receive swine flu vaccine" increased the likelihood of being vaccinated [OR: 2.160, (95%CI 1.135-4.111), p=0.019]. CONCLUSION: Although asthmatic children are considered to be a high-priority group for Influenza A/H1N1 vaccination, we found low uptake of vaccine among our patients. Beliefs and attitudes rather than asthma control parameters influenced parental decisions for immunization. Understanding the underlying determinants for refusing the vaccine will help to improve vaccine campaigns in advance of a future outbreak.

TRACK as a complementary tool to GINA and NAEPP guidelines for assessing asthma control in pre-school children.

BACKGROUND: In this study, our goal is to evaluate the consistency between TRACK and the asthma control levels assessed according to the GINA and NAEPP guidelines in children younger than 5 years of age. METHODS: Patients under 5 years old, who were followed up for recurrent wheezing for at least 1 year have been included. Parents were given the TRACK questionnaire and the control level of asthma according to GINA and NAEPP guidelines were determined by a pediatric allergist blinded to TRACK scores. Patients were classified into two groups regarding the compatibility of the control level between TRACK and both GINA and NAEPP guidelines. RESULTS: A total of 365 questionnaires were evaluated. The TRACK cut-off point of 80 provided the most consistent balance between sensitivity and specificity for the compatibility with both GINA and NAEPP (for GINA 0.763 and 0.663, kappa = 0.487, p < 0.001 and for NAEPP 0.761 and 0.769, kappa = 0.524, p < 0.001, respectively). When 80 was taken as the cut-off value for TRACK, the compatibility rate of asthma control levels between TRACK and GINA and TRACK and NAEPP was 71.0 and 76.4%, respectively. About 70.1% of the patients who had TRACK scores over 80 and had mild asthma were grouped as controlled according to GINA and 50.0% of patients who had TRACK scores over 80 and had moderate to severe asthma was grouped as uncontrolled according to GINA (p = 0.019). CONCLUSION: TRACK is compatible with NAEPP and GINA in majority of asthmatic children under 5 years of age. Nevertheless, there is a discrepancy between guidelines and TRACK scores; therefore, it should be used in conjunction with a detailed clinical examination in order to make a better decision for assessing the control levels and management plan.

Anaphylaxis/angioedema caused by honey ingestion.

Honey allergy is a very rare, but serious health condition. In this study, we presented six patients who described systemic allergic reactions after ingestion of honey. Three of the six patients had suffered from anaphylaxis. Honey-specific IgE was measured and skin-prick tests for honey were performed to diagnose honey allergy. The results of honey-specific IgE of all patients were positive. Four patients had high serum-specific IgE for honey bee venom and two of five patients had also experienced anaphylaxis due to bee stings. Skin-prick tests with honey and pollens were positive in five patients. Honey is one of the foods that can cause severe systemic reactions. Specific IgE and skin-prick tests are helpful for the diagnosis of honey allergy.

Viral etiology in infants hospitalized for acute bronchiolitis.

Acute bronchiolitis is predominantly a viral disease. Respiratory syncytial virus is the most common agent, but other newly identified viruses have also been considered as causes. The aim of the present study is to determine the respiratory viruses causing acute bronchiolitis in hospitalized infants. Infants younger than 2 years of age who were hospitalized for acute viral bronchiolitis in a children's hospital between November 2011 and May 2012 were evaluated for the presence of viruses as etiologic agents using a realtime polymerase chain reaction method.A total of 55 infants were included in this study. The mean age of the children was 6.98±5.53 months, and 63.6% were male. In the 55 children, 63 viruses were detected. A single viral pathogen was detected in 47 (85.5%) patients, and two viruses were co-detected in 8 (14.6%) patients. Respiratory syncytial virus was the most common virus identified, accounting for 25 (45.5%) cases, followed by rhinovirus (n=9, 16.4%), and human metapneumovirus (n = 8, 14.5%).Although respiratory syncytial virus remains the major viral pathogen in infants hospitalized for acute broncholitis, more than half of bronchiolitis cases are associated with other respiratory viruses.

The effect of obesity on the level of fractional exhaled nitric oxide in children with asthma.

BACKGROUND: Several studies have demonstrated a relationship between asthma and obesity. However, the results have been conflicting with regard to the relationship between fractional exhaled nitric oxide (FeNO), used as a marker of airway inflammation in asthmatic patients, and obesity. We aimed to evaluate the association of FeNO with obesity and obesity-related metabolic complications in asthmatic and nonasthmatic children. METHODS: The study population included children aged between 6 and 17 years and consisted of 4 groups: obese asthmatics (n = 52), normal-weight asthmatics (n = 49), obese nonasthmatics (n = 51) and normal-weight nonasthmatics (n = 42). FeNO measurement and spirometry were performed for all patients. To evaluate the metabolic complications, serum lipids, glucose and insulin levels were measured. Insulin resistance (IR) was estimated by the homeostasis model assessment, HOMA-IR. All participants were evaluated for the presence of metabolic syndrome (MS). RESULTS: The mean age for the 194 subjects participating in the study was 11.6 ± 2.5 years. The FeNO level of asthma patients with MS was not different from those without MS (14.5 ± 8.0 and 16.7 ± 8.7, respectively, p = 0.449). In the nonasthmatic group, subjects with MS had a higher FeNO level than subjects without MS (12.5 ± 5.1 and 17.3 ± 8.3, respectively, p = 0.014). Spearman's rank correlation coefficients revealed a positive correlation between FeNO and body mass index (BMI; p = 0.049, r(2): 0.204) in the nonasthmatic group and after multivariate regression analysis, BMI still persisted as an independent risk factor for FeNO. CONCLUSION: We found a positive correlation between BMI and FeNO level which suggests a link between obesity and increased airway inflammation in nonasthmatic children.