Short and easy questionnaires have been developed to assess the health-related quality of life (HRQoL) in patients with chronic obstructive pulmonary disease (COPD), such as the Maugeri Foundation Respiratory Failure Questionnaire (MRF-28) and the COPD-specific HRQoL Questionnaire (VQ11). Both are valid, reliable, and sensitive, but their minimal clinically important differences (MCID) are unknown. Consequently, this study aimed to confirm the convergent validities of the MRF-28 and VQ11 and establish their MCID. A retrospective design was used to evaluate the effect of individual home-based pulmonary rehabilitation (PR) in 400 COPD patients.
Exercise tolerance, anxiety and depression based on the Hospital Anxiety and Depression Scale (HADS), and HRQoL using three questionnaires (MRF-28, VQ11, and the Visual Simplified Respiratory Questionnaire: VSRQ) were assessed before and after an individualized home-based PR program (5 sessions of 30–45 mins/week for 8 weeks, including a weekly session supervised by a team member).
PR improved all measured variables ( p < 0.0001). The correlations were significant ( p < 0.0001) between VSRQ and MRF-28 (r = −0.685 at baseline and r = −0.686 after the PR program), and between VSRQ and VQ11 (r = −0.691 at baseline and r = −0.753 after the PR program). Moreover, changes in score (delta between after and before PR program) of VSRQ were also significantly correlated ( p < 0.0001) to changes in score of MRF-28 (r = −0.372) and VQ11 (r = −0.423). Last, we calculated MCID of −5.2 and −2.0 units for MRF-28 and VQ11, respectively.