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Background The International Study of Asthma and Allergies in Childhood (ISAAC) showed a wide variability in prevalence and severity of allergic rhinitis (AR) and rhinoconjunctivitis (ARC), in addition to other atopic diseases (Asher et al, 2006). 1 The Global Asthma Network (GAN) has continued to study these conditions. Objective To estimate the prevalence of AR and ARC in children and adolescents in Mexico and to assess their association with different risk factors. Methods GAN Phase I is a cross-sectional, multicentre survey carried out in 15 centres corresponding to 14 Mexican cities throughout 2016–2019 using the validated Spanish language version of the GAN Phase I questionnaires. The questionnaires were completed by 35 780 parents of 6–7 year old primary school pupils (children) and by 41 399 adolescents, 13–14 years old. Results The current and cumulative prevalence of AR was higher in the adolescents (26.2–37.5%, respectively) in comparison to the children (17.9–24.9%, respectively), especially in female participants. This tendency was also observed in the current prevalence of ARC, where 15.1% of female adolescents reported nasal symptoms accompanied with itchy-watery eyes in the past year. The most important risk factors for AR and ARC were the presence of wheezing in the past 12 months, wheezing in the first year of life, the previous diagnosis of asthma and eczema symptoms. Furthermore, allergic symptoms had a negative tendency concerning altitude. Conclusion This is the largest AR epidemiological study ever conducted in Mexico. It shows an increase in AR prevalence, as well as significant associations with modifiable risk factors, which could help to establish recommendations to reduce the burden of this condition.

BackgroundTwo different allergic rhinitis (AR) symptom phenotype classifications exist. Treatment recommendations are based on intermittent–persistent (INT-PER) cataloging, but clinical trials still use the former seasonal AR–perennial AR (SAR-PAR) classification. This study was designed to describe how INT-PER, mild–moderate/severe and SAR-PAR of patients seen by allergists are distributed over the different climate zones in a (subtropical country and how these phenotypes relate to allergen sensitization patterns.MethodsSix climate zones throughout Mexico were determined, based on National Geographic Institute (Instituto Nacional de Estadística y Geografía) data. Subsequent AR patients (2–68 years old) underwent a blinded, standardized skin-prick test and filled out a validated questionnaire phenotyping AR.ResultsFive hundred twenty-nine subjects participated in this study. In the tropical zone with 87% house-dust mite sensitization, INT (80.9%; p < 0.001) and PAR (91%; p = 0.04) were more frequent than in the subtropics. In the central high-pollen areas, there was less moderate/severe AR (65.5%; p < 0.005). Frequency of comorbid asthma showed a clear no -south gradient, from 25% in the dry north to 59% in the tropics (p < 0.005). No differences exist in AR cataloging among patients with different sensitization patterns, with two minor exceptions (more PER in tree sensitized and more PAR in mold positives; p < 0.05).ConclusionIn a (sub)tropical country the SAR-PAR classification seems of limited value and bears poor relation with the INT-PER classification. INT is more frequent in the tropical zone. Because PER has been shown to relate to AR severity, clinical trials should select patients based on INT-PER combined with the severity cataloging because these make for a better treatment guide than SAR-PAR.

Background Describe AD prevalence and identify associated risk factors in Mexican children. Methods Multi-centric, cross-sectional ambiental survey. We applied the standardized Spanish-version ISAAC questionnaire to children's tutors aged 6 to 7 years in 8 Mexican cities. Sampling units randomly selected from local schools with advisable sample size of 3000 questionnaires per centre. Questions to evaluate actual AD: Has your child had itchy rash at any time in the past 12-months? Has this itchy rash at any time affected any of the following places: the folds of the elbows, behind the knees, in front of the ankles, under the buttocks or around the neck, ears or eyes? A risk analysis was made through multivariate logistical regression, central tendency and dispersion measures were obtained with respective 95% confidence intervals. Results A total of 25,809 questionnaires were applied at 274 schools. For current AD symptoms 18,095 questionnaires were analyzed and for severe current AD symptoms 19,173. Current AD symptoms mean global prevalence was 6.1% (95% CI, 5.7-6.4%). Mean prevalence and 95% CI per center: Monterrey 4.2% (3.5-4.9%), Mexicalli 6.3% (5.3-4.9%), Ciudad Victoria 2.3% (1.8-2.9%), Tijuana 4.9%(4.1-5.7%); North DF 8.5% (7.6-9.4%), Southeasat DF 9.4% (8.0-10.7%), Toluca 5.4% (4.6-6.2%); Veracruz 5.3% (4.3-6.2%); Villahermosa 8.6% (7.3-9.8%). Severe current AD symptoms mean global prevalence was 0.7% (95% CI, 0.6-0.9). Mean prevalence and 95% CI per center: Monterrey 0.6% (0.3-0.9%), Mexicalli 0.8% (0.5-1.2%), Ciudad Victoria 0.3% (0.1-0.6%), Tijuana 0.9% (0.5-1.2%); North DF 1.1% (0.7-1.5%), DF Southeast 1% (0.5-1.4%), Toluca 0.3% (0.1-0.5%); Veracruz 0.7% (0.4-1.1%); Villahermosa 1.2% (0.8-1.7%). Identified risk factors for current AD symptoms: presence of allergic rhinitis symptoms OR 1.94 (95% CI, 1.53-2.14; P ≤ 0.005); conjunctivitis symptoms OR 1.81 (95% CI, 1.53-2.14; P ≤ 0.005); accumulated asthma symptoms OR 1.51 (95% CI, 1.3-1.76; P ≤ 0.03). Identified risk factors for severe current AD symptoms: presence of conjunctivitis symptoms OR 2.20 (95% CI, 1.42-3.4; P ≤ 0.005); accumulated asthma symptoms OR 2.16 (95% CI, 1.38-3.39; P ≤ 0.005); use of acetaminophen in the first year of life OR 1.80 (95% CI, 1.21-2.69; P ≤ 0.005). Conclusions Current AD symptoms prevalence was higher at north DF, followed by Toluca and southeast DF; current severe AD symptoms were higher at Villahermosa, followed by north DF and Tijuana. The presence of rhinoconjuntivitis and accumulated asthma symptoms doubles the risk for current AD and current severe symptoms in Mexican children and Acetaminophen use in the first year of life was associated with severe current AD symptoms.

Background Asthma affects around 300 million people around the world, and is expected to increase 100 million more in the next 15 years. Multiple risk factors had been associated with its prevalence, though little is known about the regional variations of these risk factors. Objective Identify the main risk factors associated to the presence of wheezing in the last 12 months in Mexican children aged 6 to 7 years old. Methods Multicentric, cross-sectional survey. The standardized Spanish-version ISAAC questionnaire was applied to tutors of children aged 6 to 7 years old in 8 cities of the Mexican Republic. Sample was randomly selected through public and private schools of each city, and a sample of 3000 children per center was advisable. Risk analysis was made through multivariate logistical regression, central tendency and dispersion measures were obtained with respective 95% confidence intervals. Results Nine centers of 8 cities participated, data of 24,504 questionnaires were analyzed with an answer rate of 90.7%. Grouping the 9 participating centers, a prevalence of 8.4% (95% CI, 8.1-8.8%) for wheezing in the last 12 months was found, with the next distribution: Monterrey 8.6% (95% CI, 7.6-9.6%), Mexicali 9.6% (95% CI, 8.4-10.7%), Ciudad Victoria 8.6% (95% CI, 7.5-9.7%), Villahermosa 10.2% (95% CI, 9.1-11.4%), Northern Distrito Federal 7.3% (95% CI, 6.5-8.2%), Southeast Distrito Federal 9.9% (95% CI, 8.5-11.3%), Toluca 5.9% (95% CI, 5.1-6.7%), Tijuana 8.2% (95% CI, 7.2-9.2%), Veracruz 9.7% (95% CI, 8.4-10.9%). Identified risk factors for the presence of wheezing in the last 12 months were: nasal symptoms accompanied with ocular symptoms (itching and tearing) in the last 12 months, OR 2.31 (95% CI, 2.01-2.66; P ≤ 0.0001). Nasal symptoms (blocked nose, runny nose, and/or itching) in the last 12 months, OR 2.2 (95% CI, 1.66-2.92; P ≤ 0.0001). Hay fever diagnosis by medical staff OR 2.02 (95% CI, 1.72-2.37; P ≤ 0.0001). Atopic dermatitis symptoms (classic morphology and distribution) in the last 12 months, OR 1.65 (95% CI, 1.39-1.96; P ≤ 0.0001). Use of antibiotics in the first 12 months of life, OR 1.68 (95% CI, 1.48-1.90; P ≤ 0.0001). Use of acetaminophen in the last 12 months, OR 1.49 (95% CI, 1.35-1.65; P ≤ 0.0001). Conclusions The presence of allergic rhinoconjuntivitis symptoms in the last 12 months doubles the risk for the presence of wheezing in Mexican children.

Background According to ISAAC symptoms of allergic rhinoconjunctivitis (RC), have a worldwide prevalence of 8.5% in school children. Multiple risk factors had been associated with its prevalence, though little is known about the regional variations of these risk factors. Objective Identify the prevalence and the main risk factors associated to the presence of symptoms of rhinoconjunctivitis in the last 12 months in Mexican school children. Methods Cross-sectional, multicenter, prospective, based in ISAAC methodology of 9 registered sites in 8 cities (north, center and south of the Mexican Republic) with a validated and standardized survey applied to tutors of children aged 6 to 7 years old. Risk analysis was made through multivariate logistical regression, central tendency and dispersion measures were obtained with respective 95% confidence intervals. Results 24,902 surveys were obtained. The prevalence and 95%CI of symptoms of rhinitis was as follows: Monterrey 23%(21.4-24.5%), Mexicali 28.7% (26.9-30.5%), Ciudad Victoria 21.3%(19.7-22.8%), Villahermosa 39% (37-41%), North Federal District 45.6% (44.1-47.2%), Toluca-18.6% (17.3-20%), Tijuana 24.5% (22.9-26.1%), southeast Federal District 53%(50.7-55.4%) Veracruz 25% (23.1-26.8%) and conjunctivitis: Monterrey 8.8% (7.8-9.9%), Mexicali 13.2%(11.9-14.5%), Ciudad Victoria 7.3%(6.3-8.3%), Villahermosa 18.7% (17-20.3%), North Federal District 20.4%(19.1-21.7%), Toluca 7.3%(6.4-8.2%), Tijuana 8.7%(7.6-9.7%), southeast Federal District 25.1%(23-27.1%) Veracruz 8.7% (7.5-9.9%). The prevalence de rhinoconjunctivitis were 12.8%. Identified risk factors for the presence of rhinitis in the last 12 months were: asthma symptoms in the last 12 months OR-2.59 (95% CI, 2.25-2.98; P ≤ 0.0001), wheezing ever OR-1.78 (95% CI, 1.61-1.96; P ≤ 0.0001), eczema symptoms in the last 12 months OR-1.61 (95% CI, 1.35-1.93; P ≤ 0.0001), atopic dermatitis ever OR-2.97 (95% CI, 2.52-3.51; P ≤ 0.0001). Identified risk factors for the presence of conjunctivitis in the last 12 months were: wheezing ever OR-1.88 (95% CI, 1.64-2.16; P ≤ 0.0001), asthma symptoms in the last 12 months OR-2.97 (95% CI, 2.52-3.51; P ≤ 0.0001) eczema symptoms in the last 12 months OR-1.95 (95% CI, 1.58-2.41; P ≤ 0.0001), atopic dermatitis ever OR-2.14 (95% CI, 1.81-2.54; P ≤ 0.0001). Conclusions The highest prevalence of rhinoconjunctivitis in Mexican School Children is in the southeast of the Federal District. The presence of asthma symptoms in the last 12 months, wheezing ever, eczema symptoms in the last 12 months, atopic dermatitis ever, risk factors are present symptoms of rhinoconjunctivitis.