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

Objective 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.Methods 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.Results 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.Conclusion 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.