Relations among asthma knowledge, treatment adherence, and outcome

Background: Asthma knowledge is frequently assumed to be a prerequisite for optimal asthma treatment. However, the validity of existing asthma knowledge questionnaires has not been rigorously examined, and no contemporary measure of asthma knowledge has received widespread acceptance. Objective: To construct and examine the psychometric properties of an asthma knowledge instrument, and its association with demographic and psychosocial variables, asthma medication adherence, and treatment outcome. Methods: A 25-item Asthma Knowledge Questionnaire was developed with input from national pediatric asthma experts. Parents of 155 children with asthma completed the Asthma Knowledge Questionnaire as well as demographic, family functioning, and home environment measures. Asthma outcomes and adherence with inhaled medication was measured across 12 months. Results: Despite the many steps taken to develop a strong measure of asthma knowledge, reliability was relatively poor. There was also no association between asthma knowledge and treatment adherence or outcomes. Furthermore, asthma knowledge was not a unidimensional construct and was not a simple function of education. Conclusions: Findings from this study, in combination with previous studies of asthma knowledge questionnaires, suggest that the construction of a simple self-report asthma knowledge instrument for use as a primary outcome measure demonstrating mastery of asthma self-management skills may not be achievable.