A 55 year old male, who is a known case of severe persistent asthma since 14 years of age presents with acute exacerbation of asthma. The disease was well controlled upto 54 years with high dose inhaled corticosteroids. For the past 12 months the disease was not in good control. He complains of nocturnal cough, limitation of daily activities in spite of good compliance with medications. Spirometry was suggestive of bronchial asthma with partial irreversibility of airway obstruction. What is the cause for poor disease control?