Rationale: Despite the availability of effective treatment to reach symptom control, nearly half of the asthma patients remain inadequately controlled. There is a need for timely and appropriate treatment of patients with uncontrolled asthma. Improving asthma control could be achieved by a better identification of causes followed by remediating modifiable factors in primary care or referral to secondary care. However, major gaps in evidence-based asthma practice exist in primary care. So far, there is a lack of knowledge on the prevalence of inadequate asthma and associated characteristics.

Objective: The primary objective is to determine the proportion of primary care patients with inadequate asthma control, as assessed during a regular control consultation with the general practice nurse.

Study design: This is a non-interventional prospective observational study, taking place in a real-world primary care setting. The AsthmaOptimiser tool will be used during regular asthma consultations in primary care, which the healthcare provider will fill in together with the patient. The AsthmaOptimiser tool creates an overview of factors and characteristics that may be associated with uncontrolled asthma, and subsequently provides a guideline-based management suggestion. Additionally, we will perform qualitative interviews to collect experiences and perspectives of healthcare providers on their use of the AsthmaOptimiser tool, including, but not limited to, ease of use, points of improvement, and on their implementation of the management suggestions.

Study population: Patients diagnosed with asthma, who attend a pre-planned primary care asthma review, are eligible to participate. A limited number of in- and exclusion criteria will be adopted, to make sure the research population closely resembles the real world.

Main study parameters/endpoints: The primary endpoint is the proportion of patients with inadequate asthma control. Inadequate asthma control will be defined as an exacerbation in the past 4 weeks and/or an ACQ6 (i.e., Asthma Control Questionnaire) score >0.75.

Inclusion Criteria:

• Aged ≥ 18 years
• Physician diagnosis of Asthma
• Capacity to provide written informed consent

Exclusion Criteria:

• Life expectancy of less than 1 year
• Inability to understand Dutch
• Any other condition which, at the GPs and/or investigator's discretion, is believed to present a safety risk or may impact the study results
• Patients participating in a clinical trial that may distort outcomes in this observational study.

Primary care patients with a current asthma diagnosis, who are scheduled to have in-person asthma review consultations with a primary care nurse, will be recruited from primary care practices located in the northern part of the Netherlands. The population includes men and women ≥18 years of age with clinically diagnosed asthma. The diagnosis of asthma is allowed to be a clinical diagnosis rendered by a doctor, without the requirement to conduct additional confirmatory testing. Furthermore, a limited number of in- and exclusion criteria will be adopted, to make sure the research population closely resembles the real world.