Prevalence, incidence and adherence
of “difficult-to-treat” adult asthma in the Netherlands.

Rationale:

Patients with severe refractory asthma pose a major healthcare problem. It has become increasingly clear that, for the development of new targeted therapies, there is an urgent need for further characterisation and classification of these patients. However, the exact prevalence of patients with severe refractory asthma is unknown and in addition to this, the question remains if patients who have difficult-to-treat asthma have truly severe refractory asthma or are not adherent with their medication or have an incorrect inhalation technique. Data on this is lacking.



Objective:

1. To describe the prevalence and incidence of “difficult-to-treat” adult asthma in the Netherlands.

2. To describe factors associated with adherence with pulmonary medication in patients with difficult-to-treat airway disease.

3. To describe the inhalation technique in adherent patients with difficult-to-treat airway disease.

4. To compare patients’ characteristics of patients with difficult-to-treat asthma with optimal treatment adherence and adequate inhalation technique and severe controlled asthma with optimal treatment adherence and adequate inhalation technique.



Study design:

Descriptive observational study.

Aims:

1. To describe the prevalence and incidence of difficult-to-treat adult asthma in the Netherlands;

2. To describe factors associated with adherence with pulmonary medication in patients with difficult-to-treat airway disease;

3. To score the inhalation technique in patients using high dose inhaled corticosteroids who are adherent to treatment;

4. To assess the prevalence of patients with truly severe, refractory asthma and describe the characteristics of these patients.

N/A

All patients listed in 73 community pharmacies and using inhaled corticosteroids will be selected, their characteristics will be encoded and translated into a database. This database will be send to the AMC.



From this database the codes of patients using high dose of inhaled corticosteroids will be selected. The pharmacies will translate these codes to the original patient numbers and send the patients questionnaires. These can be returned directly to the AMC.



From this database containing information about high dose ICS prescription, medication adherence, asthma control and patients characteristics the patients will be divided into 3 categories:

1. Asthma;

2. Mixed asthma/COPD (patients with asthma and ≥ 10py);

3. COPD.



Patients with COPD will be excluded from further analyses and the prevalence and incidence of difficult-to-treat asthma and the adherence to inhaled therapy will be determined.



Additionally, all patients from aim 2 who are adherent with asthma treatment will receive inhalation technique assessment and instructions.



These groups are determined by:

1. Difficult-to-treat asthma;

2. Optimal treatment adherence;

3. Controlled or uncontrolled asthma.