Optimal Type of Inhaler in Cough Variant- or Cough Predominant Asthma

Cough may be caused by both cough variant asthma or cough predominant asthma in 20-30% adults with chronic cough. Asthma management is based on inhaled therapy, mainly on inhaled glucocorticosteroids (ICS). The efficacy of inhaled therapy depends on type of inhaler and proper inhalation skills (1-2). Many of patients with asthma (as well as with COPD) make mistakes during inhaling, what negatively affect efficacy of management (3-4). Additionally, in cough variant- or cough predominant asthma aerosol or dry powder of inhaler may tease upper airway and induce cough (5).

Therefore aim of the study is to analyze if type of inhaler (Dry Powder Inhaler, DPI vs pressurized Metered Dose Inhaler, MDI) affects the efficacy of the management in cough variant or cough predominant asthma.

In all patients cough severity and tolerance of therapy will be analyzed during therapy with budesonide and/ or formoterol administered by DPI and MDI used in turn. Order of using different types of inhalers will be accidental.

Twenty two patients with cough variant- or cough predominant asthma will be enrolled into the study.

The sample size for the study was determined assuming that initially cough severity is at least 50/100 mm in VAS scale and minimal difference will be 20/100 mm. Providing these conditions, the sample size is 18 patients (α error 5%, power 80%); the sample was increased by 20% assuming drop out during the study.

Initially cough severity (in 10 mm VAS scale), cough related quality of life (in Leicester Cough Questionnaire, LCQ) and number of cough episodes during 2 hours will be estimated. Additionally Asthma Control Test (ACT), Asthma Quality of Life Questionnaire (AQLQ) and spirometry will be performed.

Then, budesonide or budesonide and formoterol will be stared in Aerolizer / Breezhaler or pMDI. Inhalation technique will be checked and if needed -corrected.

After 14 days, cough severity, LCQ, number of cough episodes, ACT, AQLQ, spirometry and inhalation technique will be assessed.

Then, type of inhaler will be changed, but the same doses of ICS and LABA will be administered. Once again inhalation technique will be checked and corrected if needed.

After 28 days, cough severity, LCQ, number of cough episodes, ACT, AQLQ, spirometry and inhalation technique will be assessed again.

The results will be based on differences in cough severity, cough related quality of life, asthma related quality of life, control of asthma and number of cough episodes between therapy with DPI and MDI.

Inclusion criteria

• Informed consent for participating in the study
• Age ≥18 years
• Cough variant asthma or cough predominant asthma diagnosed and treated with inhaled corticosteroids (ICS) regularly at least 8 weeks prior to enrollment

Exclusion criteria

• Lack of informed consent
• Age <18 years
• Diagnosis of cough variant- or cough predominant asthma shorter than 8 weeks before enrollment
• Symptoms of infection or asthma exacerbation 4 weeks prior to beginning of the study or during the study
• Comorbidity that could prevent patient from using DPI or MDI (i e. advanced vision disorders, some mental diseases, advanced neurological diseases).