Health-related quality of life measurement in asthma and chronic obstructive pulmonary disease: review of the 2009-2014 literature

Background: Asthma and chronic obstructive pulmonary disease (COPD) are frequent in the general population. These diseases can worsen the quality of life of people suffering from them, limiting their daily activities and disrupting their sleep at night. Some questionnaires to measure the impact of the diseases on the daily life of patients are available. The measurements of subjective outcomes have become a part of clinical practice, and are used very frequently in clinical trials. Our aim was to describe how data on HRQoL in asthma and COPD are reported in papers published in the medical literature. Methods: We identified papers on the recent respiratory drugs (chemical, not biological), that reported the HRQoL measurement and that were published from 2009 to April 2014. We planned to describe data about HRQoL, and we had no intention of comparing the degree of efficacy of drugs. Results: The most used questionnaires are the Asthma Quality of Life Questionnaire (AQLQ) and the Saint George's Respiratory Questionnaire (SGRQ). These tools, administered at the baseline and at the end of the study (and interim evaluations in the longer studies) allowed for the identification of improvements as perceived by the patient after the treatment, even if in some cases these improvements were limited and not clinically relevant. Subjective measurements have always been placed among the secondary endpoints and the number of patients (estimated for the main endpoint) has often statistically overestimated the result. In addition, it is clear that subjective data is normally reported, but rarely commented on. Conclusions: There are some methodology aspects that should be discussed in more depth, for example the necessity to express variations in the subjective perception, not as p-value but as effect-size.