Resources for practices delivering asthma care What is ADxDA?
The ADxDA tool predicts the probability that an individual has asthma. It is designed to be easy-to-use and use only information that are commonly available in the patient’s electronic health record or can be collected during a primary care consultation (either face to face or remotely). ADxDA uses a prediction model to calculate the probability of the diagnosis being asthma, and suggests further steps that could help confirm (or refute) a diagnosis. The process of making a diagnosis of asthma can take time which can be concerning for patients, so ADxDA has been designed to promote shared decision making and provide resources to explain the process to patients.
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How was the ADxDA tool developed?
The underpinning prediction model was created in a UK based cohort of 11,972 participants aged up to 25 years of age from the Avon Longitudinal Study of Parents and Children (ALSPAC). The design features of the ADxDA tool have been developed following two qualitative studies of primary care clinicians, individuals with asthma and parents/carers of children with asthma.
What does the probability indicate?
The probability indicates the likelihood that an individual has asthma that will require treatment with inhaled corticosteroids (we defined this in the prediction model as three prescriptions over the next year). Guidelines recommend that most individuals with asthma should be treated with inhaled corticosteroids and that only the small minority with infrequent, short-lived wheeze can be treated with short acting beta-agonists alone.
Has the ADxDA tool been validated?
Yes. The prediction model has been checked in the dataset in which it was made (internal validation) and in routinely collected primary care records (external validation).
Why is a feasibility study needed?
Whilst the prediction model has been validated, it is now important to understand how it works in clinical practice. This study is the next step in that process; to understand how useful and acceptable the ADxDA tool is for clinicians and patients. Before we can know for sure if the ADxDA tool improves the accuracy of an asthma diagnosis a randomised controlled trial will be needed.
More information
- A detailed description of the methods used to create the prediction model is available here
- The final report is currently being written (Feb 2022) but an abstract of the results is available here
Clinical guidance
The prediction model should be used when assessing a child or young person who you think may have asthma.
The prediction model was developed in children and young adults up to 25 years of age. Predictions for individuals outside this age range is untested.
Disclaimer: The ADxDA tool calculates the probability of an individual having asthma that requires at least three inhaled corticosteroids in the next 12 months. It presents the average probability of individuals with the same clinical features factors as those entered for that person. It may inform, but does not replace clinical judgement.
