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

BACKGROUND

Some 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.

METHODS

Observational, analytical, cross-sectional study in children aged 6-15 years old with SA at HA (2640 m). Skin prick tests (SPT), serum IgE, exhaled fraction of nitric oxide (FE_NO ), spirometry, and asthma questionnaire (ACT) were performed. Associations were explored by Pearson or Spearman coefficients.

RESULTS

We included 61 children. Most patients were male (61.3%), median age: 10 years (Interquartile range [IQR]: 8-12), median BMI: 17 kg/m² (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: 348 UI/mL (IQR: 154-760) and FE_NO : 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).

CONCLUSIONS

These 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.