Measuring patient knowledge of asthma: a systematic review of outcome measures

Asthma self-management education is a key component of international guidelines. No gold standard patient centred outcome measure exists for asthma knowledge. Our aim was to identify high-quality, validated, and reliable outcome measures suitable for use in either the research or clinical setting.

A systematic review was performed to identify outcome measures able to assess asthma knowledge in people with asthma. An electronic database search was made of MEDLINE, BNI, CINAHL, CDSR, DARE, Health Technology Assessment, NHS Economic Evaluation Database, EMBASE, AMED, PsychInfo and ISI. A review of grey literature was also performed. Articles were included if they described the development and psychometric testing of an asthma knowledge measure. The quality of each outcome measure was assessed according to published guidance. Content validity, construct validity, criterion validity, internal consistency, responsiveness, floor and ceiling effects, reproducibility, and interpretability were evaluated and given a rating of either "positive," "intermediate," or "negative."

Eighteen outcome measures met the inclusion criteria. None of these had a positive rating for all eight psychometric properties. Three outcome measures achieved either a positive or intermediate rating for content validity, construct validity, internal consistency, and reproducibility. As none of the articles had sufficient data regarding floor and ceiling effects, responsiveness, or interpretability, these properties could not be assessed.

We have been unable to identify any high-quality patient-centered asthma knowledge outcome measures. Any conclusions drawn from trials using such measures should therefore be interpreted with caution.