Longitudinal HRQoL shows divergent trends and identifies constant decliners in asthma and COPD

Monitoring of lung function alone does not adequately identify the high-risk patients among elderly asthma and COPD cohorts. The additional value of Health-Related Quality of Life (HRQoL) development in the detection of patients with a disabling disease in clinical practice is unclear. The aim of this study was to statistically examine the individual development of HRQoL measured using respiratory-specific AQ20 and generic 15D questionnaires.

The HRQoL of COPD (N = 739) and asthma (N = 1329) patients was evaluated at 0, 1, 2, and 4 years after recruitment. To determine a five-year HRQoL change for each patient we used mixed-effects modelling for linear trend.

In COPD, the majority (60-80%) of the individuals showed declining trend, whereas in asthma, the majority (46-71%) showed no attenuation in HRQoL. The proportion of constant decliners was estimated higher with the 15D both in asthma (6.3%) and COPD (6.3%) than with AQ20 (3.5 and 4.5%, respectively). The first measurement of HRQoL was found to predict future development of HRQoL. In asthma, obesity-related diseases such as hypertension, diabetes and gastro-esophageal reflux disease best explained the decline, whereas in COPD, age and the level of bronchial obstruction were the main determinants.

Based on the five-year follow-up, the HRQoL trends significantly diverging from each other could be identified both among the asthma and COPD patients. Compared to cross-sectional HRQoL, the HRQoL trend over a clinically relevant period of time allows us to ignore, to a great extent, the random error of self-assessed HRQoL and thus, it may offer a more accurate measure to describe the disease process.