["Questionnaire on Quality of Life in Asthma"--studies of the dimensionality and references for evaluation]

Abstract

The FLA, representing the German revision of the LWAQ (Hyland et al., 1991), is one of the few available questionnaires for measuring the disease-specific quality of life (QOL) in adults suffering from asthma. The present study aimes at analysing the structure and reliability of the FLA and also at improving its feasibility. Therefore, the inventory has been analysed in terms of its dimensional structure, internal reliability, and homogeneity. To facilitate the interpretation of the test outcomes and to obtain more differentiated predictors, the 40 items of the FLA were--according to theoretical considerations--categorised into three dimensions ("Physical Symptoms", "Psychological Distress" and "Functional Status"). In this study the FLA was applied with a sample of 136 hospitalised asthma patients of varying severity (63 male, 73 female, meanage; 49.5 years) in the North German "Allergie- und Asthmaklinik Wilhelm Gronemeyer, Bad Lippspringe, to evaluate the reliability of the total scale and its dimensions. The findings of the item analysis with regard to selectivity and item difficulty yielding satisfying results are presented in multiple tables. Furthermore, recommendations for the transformation of original values into summary scores and evaluation procedures were developed to improve the strength of evidence in the data. The summary scores, which can be computed for both total scale and the three dimensions, facilitate intra- and interindividual comparison of the patients' quality of life and point to special deficits in different QOL domains requiring specific therapeutic interventions. Finally, the FLA's range of application, its limitations, developmental perspectives and proposals for improvement are discussed.