Minimal clinically important differences for patient-reported outcome measures of fatigue in patients with COPD after pulmonary rehabilitation.
Fatigue is a burdensome and prevailing symptom in patients with chronic obstructive pulmonary disease (COPD). Pulmonary rehabilitation (PR) improves fatigue however, interpreting when such improvement is clinically relevant is challenging. Minimal clinically important differences (MCIDs) for instruments assessing fatigue are warranted to better tailor PR and guide clinical decisions. We estimated MCIDs for the functional assessment of chronic illness therapy-fatigue subscale (FACIT-FS), the modified-FACIT-FS and the checklist of individual strength-fatigue subscale (CIS-FS), in patients with COPD after PR.Data from patients with COPD who completed a 12-weeks community-based PR programme were used to compute the MCIDs. The pooled MCID was estimated by calculating the arithmetic weighted mean, resulting from the combination of anchor (weight-2/3) and distribution-based (weight-1/3) methods. Anchors were patients’ and physiotherapists’ global rating of change scale, COPD assessment test, St. George’s respiratory questionnaire (SGRQ) and exacerbations. To estimate MCIDs we used mean change, receiver operating characteristic curves and linear regression analysis for anchor-based approaches, and 0.5*standard deviation, standard error of measurement (SEM),1.96*SEM and minimal detectable change for distribution-based approaches.Fifty-three patients with COPD (79%male, 68.4±7.6years, FEV148.7±17.4%predicted) were used in the analysis. Exacerbations, the SGRQ-impact and the SGRQ-total scores fulfilled the requirements to be used as anchors. Pooled MCIDs were 4.7 for FACIT-FS, 3.8 for the modified-FACIT-FS and 9.3 for the CIS-FS.The MCIDs proposed in this study can be used by different stakeholders to interpret PR effectiveness.