Five-year changes in generic and disease-specific patient-reported outcome measures in stable COPD: a real-world...

Evidence comparing the long-term performance of generic and disease-specific patient-reported outcome (PRO) measures in chronic obstructive pulmonary disease (COPD) remains limited. This study compared five-year longitudinal changes and evaluative performance of commonly used generic and disease-specific PRO measures in stable COPD.

This secondary analysis used data from a single-center longitudinal cohort of stable COPD outpatients. Participants completed assessments at baseline and five-years later. Disease- specific instruments included the COPD Assessment Test (CAT) and St. George's Respiratory Questionnaire (SGRQ). Generic instruments included the Medical Outcomes Study 36-Item Short Form (SF-36) and EQ-5D-5L. Distribution-based indices of five-year change were calculated using effect size (ES) and standardized response mean (SRM). Associations between changes in forced expiratory volume in one second (FEV₁) and PRO scores were examined using Spearman correlation coefficients.

Thirty-nine participants (mean age 74 years) completed five-year follow up. Disease-specific instruments showed minimal change, with small ES and SRM values (<0.5), although the SGRQ Activity deteriorated significantly. In contrast, several SF-36 subscales, including Physical Functioning, Role Physical, Social Functioning, and Role Emotional, declined significantly. Physical and Role/Social Component Summary scores and the EQ-5D-5L utility index also deteriorated significantly. Moderate distribution-based changes (ES 0.5-0.8) were observed in selected SF-36 subscales and in the EQ-5D-5L index. Mean annual FEV₁ decline was approximately 20 mL/year and was not significantly correlated with changes in PRO scores.

In stable COPD, generic PRO measures showed greater long-term deterioration than disease-specific tools, suggesting value for monitoring gradual health decline in routine clinical practice.