Page 85 - Comprehensive treatment of patients with glucocorticoid-dependent severe asthma

Predictors of benefit from high altitude treatment
Therefore, high altitude climate therapy might be an option for patients with severe refractory asthma, irrespective of their phenotype.
The majority of the prednisone-dependent patients were able to reduce their dose of oral corticosteroids after 12 weeks of high altitude climate therapy while maintaining the level of asthma control. The degree of oral corticosteroid reduction was associated with higher symptom score and younger age, combined with low blood eosinophil count at baseline. Similar characteristics were described by Haldar and colleagues in the highly symptomatic - low eosinophilic non-obese asthma phenotype [1]. This suggests that these patients were symptomatic for other reasons than severe airway inflammation and reinforces previous studies which demonstrated that tapering of oral corticosteroids is easier in patients without eosinophilia [28].
For the group as a whole there was a significant improvement in post- bronchodilator FEV1, up to 10% of the predicted value in some patients. A previous meta-analysis had also demonstrated benefit of high altitude climate therapy in the lung function of adult patients with asthma [13]. However, we could not find any clinical or inflammatory predictor of improvement. A reduced post bronchodilator FEV1 indicates persistent airflow limitation, probably linked to inflamed and swollen airway mucosa or airway remodelling. A possible explanation could be that high altitude climate therapy reduces the thickness of the airway mucosa or might even reverse airway modelling, irrespective of the patient characteristics at admission, but this remains to be investigated in future studies.
Blood eosinophils did not change significantly for the group as a whole, which may be explained by a simultaneous tapering of anti-inflammatory medication. Still, there were patients showing significant reductions of blood eosinophil levels, suggesting an anti-inflammatory effect of high altitude climate therapy in selected patients. Predictors of such a reduction in blood eosinophils were a high level of total IgE and a high level of ICS (and OCS) use. This fits in with the hypothesis that continuous exposure to allergens (e.g house dust mites, fungi) at sea level had been responsible for ongoing airway inflammation and elevated blood eosinophil counts despite high dose anti-inflammatory treatment [27]. At high altitude these triggers were likely to be either absent or
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