Measuring quality of life in COPD patients: comparing disease-specific supplements to the EQ-5D-5L

Objectives: Patients with chronic obstructive pulmonary disease (COPD) show impairments in health-related quality of life (HRQL). We aimed to find a disease-specific questionnaire for routine application in large cohorts and to assess its additional explanatory power to generic HRQL tool (EQ-5D-5L). Methods: 1,350 participants of the disease management program COPD received the EQ-5D-5L combined with one of the three disease-specific tools: COPD Assessment Test (CAT), Clinical COPD Questionnaire (CCQ) or St. George's Respiratory Disease Questionnaire (SGRQ) (450 participants each). We compared metric properties and evaluated the Germany-specific experience-based values (EBVS) and utilities in comparison to the Visual Analogue Scale (VAS). We calculated the additional explanatory power of the identified disease-specific tool on VAS through regression analysis. Results: 344 patients returned the questionnaire. CAT, CCQ, and SGRQ group did not differ regarding baseline characteristics. The questionnaire specific response rates were 33.7% for CAT, 30.5% for CCQ, and 34.6% SGRQ, thereof 94.0%, 94.3%, and 65.6% valid answers, respectively. EBVS was better suited to reflect VAS than utilities. CAT increased the explanatory power by 10%. Conclusion: CAT outperformed CCQ and SGRQ, and it increased the explanatory power of VAS. EBV combined with CAT seems superior to only generic or disease-specific approaches.