Why is a new questionnaire needed?
Existing questionnaires are not valid for assessing quality
of life in severe asthma, according to the 2009 guidelines on questionnaire
construction provided by the Federal Drug and Food Administration (FDA). This
is because these questionnaires fail to address some of the quality of life deficits
experienced by this group of patients.
How did we develop the Severe Asthma Questionnaire (SAQ)?
Three studies were carried out to create a valid
health-related quality of life (HRQoL) measure in accordance with FDA
guidelines. First, we conducted a series of qualitative interviews with
patients diagnosed with severe asthma. These interviews concerned factors
affecting a patient’s HRQoL, including asthma symptoms and medication side
effects. The qualitative data from this study showed that many of the burdens
experienced by this patient group were not assessed by the asthma-specific
HRQoL questionnaires available at the time.
A draft SAQ was then made using the information gained from
the interviews. Relevant questions for a severe asthma-specific questionnaire
were chosen for this draft. This draft SAQ was evaluated in four focus groups
by patients diagnosed with severe asthma, and iterative changes were made after
each group. Participants were encouraged to suggest changes to the
questionnaires in order to improve its comprehensibility and relevance to the
experience of severe asthma.
The final step was a quantitative assessment of the SAQ,
using data from 160 patients diagnosed with severe asthma. This was the final
step in the FDA’s stepwise process of validation of a severe asthma quality of
life questionnaire.
One of our published papers provides data that
validates the use of the SAQ in clinical practice and in clinical trials of
severe asthma.
A multi-centre study collecting data on the SAQ is
currently underway. This data will be used to further assess the psychometric
properties of the questionnaire, assess sensitivity to change, and determine
its minimum clinically important difference (MCID).
The group developing the questionnaire have also
investigated the similarities between severe asthma and functional disorders
such as fibromyalgia and have published theoretical work on the reasons for
individual differences in response to biologic treatments for severe asthma.