Use of a preference-based measure of health (EQ-5D) in COPD and asthma

BACKGROUND: EQ-5D is a generic preference-based measure of health that can help to understand the impact of asthma and chronic obstructive pulmonary disease (COPD). The purpose of this paper was to synthesize literature on the validity and reliability of EQ-5D use in studies of asthma and COPD, and estimate EQ-5D utility scores associated with stage of disease. METHODS: A structured search was conducted in EMBASE and MEDLINE (1988-2007) using keywords relevant to respiratory disease and EQ-5D. Original research studies in asthma or COPD that reported EQ-5D results and/or psychometric properties were included. RESULTS: Studies that reported psychometric properties supported the construct validity, test-retest reliability, and responsiveness of EQ-5D in asthma (seven studies) and COPD (nine studies), although some evidence of ceiling effects were observed in asthma studies. In asthma studies that reported summary scores (n=11), EQ-5D index-based scores ranged from 0.42 (SD 0.30) to 0.93 (SD not reported). In COPD studies (n=8), scores ranged from 0.52 (SD 0.16) to 0.84 (SD 0.15). While few asthma studies reported scores by severity level, sufficient studies in COPD were available to calculate pooled mean utility scores according to GOLD stage: stage I=0.74 (0.62-0.87), stage II=0.74 (0.66-0.83), stage III=0.69 (0.60-0.78) and stage IV=0.61 (0.44-0.77) (most severe). CONCLUSIONS: Evidence generally supported the validity and reliability of EQ-5D in asthma and COPD. Utility scores associated with COPD stage may be useful for modeling health outcomes in economic evaluations of treatments for COPD.