Background: The age limit for some adult asthma clinical trials has recently been lowered to 12 years. In this study we have made minor modifications to the standardised version of the adult Asthma Quality of Life Questionnaire (AQLQ(S)) to make it valid for patients 12 years and older (AQLQ12+).
Methods: We have used two clinical trial databases, in which the AQLQ12+ was used, to compare the measurement properties of the questionnaire in patients 12-17 years and patients 18 years and older. A total of 2433 patients (12-75 years), with current asthma and with data that could be evaluated both at randomisation and end of treatment, were included.
Results: The analysis showed that internal consistency, responsiveness and correlations with other clinical indices were very similar in patients 12-17 years and patients 18 years and older.
Conclusion: The measurement properties of the AQLQ12+ are similar in adolescents and adults and therefore the instrument is valid for use in adult studies which include children 12 years and older.