High prevalence of house dust mite sensitization in children with severe asthma living at high altitude in a tropical country

BackgroundSome studies, mainly in Europe, have shown a low level of sensitization to house dust mite (HDM) allergens at high altitude (HA). Differently, some others in tropical countries have shown a higher level. The aim of this study was to evaluate allergens sensitization, including HDM, in children with severe asthma (SA), residents at HA in a tropical middle-income developing country. MethodsObservational, analytical, cross-sectional study in children aged 6-15 years old with SA at HA (2640m). Skin prick tests (SPT), serum IgE, exhaled fraction of nitric oxide (FENO), spirometry, and asthma questionnaire (ACT) were performed. Associations were explored by Pearson or Spearman coefficients. ResultsWe included 61 children. Most patients were male (61.3%), median age: 10 years (Interquartile range [IQR]: 8-12), median BMI: 17kg/m(2) (IQR: 16-20); Median of positive SPT: 2 (IQR: 2-3). At least one SPT was positive in 88.7% of patients and 87.9% were positive for at least one HDM. Serum IgE: 348UI/mL (IQR: 154-760) and FENO: 22 ppb (IQR: 9-41). Prebronchodilator values were (% predicted): FVC: 109.7% (15.5%), FEV1: 98.4% (+/- 16.3); FEV1/FVC: 82% (+/- 8%). SPT were inversely correlated with the FEV1/FVC (Rho: -0.34; 95% CI: -0.55 a -0.09; P=0.008). ConclusionsThese children with SA living at HA in a tropical middle-income developing country have a high prevalence of HDM sensitization. One explanation for this might be that tropical conditions, such as temperature and humidity, could modify the effect of the altitude on asthma.