Relationship between house dust mite (HDM) allergen exposure level and inhaled corticosteroid dosage in HDM-sensitive asthma patients on a self management program.

Aim: To assess whether exposure to house dust mite (HDM) allergens hampers a tapering off of inhaled corticosteroid (ICS) dosage in HDM-sensitive asthma patients.

Methods: Asthma patients sensitised to HDM allergens and using ICS were selected from general practices for this observational study. Dust samples from bed mattresses were taken to assess exposure ('no', 'low', 'intermediate' or 'high') to HDM allergens with a semi-quantitative test (Acarex). Patients were trained to use a self management plan to adjust the dose of ICS according to symptoms and peak flow. The observation period was three months.

Results: Outcomes from 123 patients were analysed. Within the 'no' and 'low' HDM exposure groups the proportion of patients who increased the dosage of their ICS medication was significantly lower than the proportion who tapered off or remained on the same dose of ICS. The group with high exposure to HDM allergens had the highest proportion of patients who increased their dose of ICS (p = 0.055).

Conclusions: High exposure to HDM allergens seems to coincide with the use of higher dose ICS treatment in asthma patients sensitised to HDM allergens.