RESPONSIVENESS OF FIVE PREFERENCE-BASED MEASURES OF HEALTH-RELATED QUALITY OF LIFE IN CATARACT

PURPOSE. Quality adjusted life years (QALYs) provide a summary of morbidity and mortality that allow comparisons among different treatment alternatives. However, there are a variety of preference-based health-related quality of life (HRQoL) measures used to estimate QALYs and these measures may yield different estimates. We compared the responsiveness of the five most widely-used preference-based HRQoL measures in patients undergoing cataract extraction with lens replacement.   METHODS. 457 adults were evaluated prior to cataract extraction with lens replacement. Patients were assessed prior to surgery, and at 1, and 6 months post surgery. At each assessment, the patients completed the Self-Administered Quality of Well-being scale (QWB-SA), the EQ-5D, the Health Utilities Index Mark 2 (HUI2) and Mark 3 (HUI3), and the SF-6D. In addition, participants completed the National Eye Institute 25-Item Visual Functioning Questionnaire (VFQ-25). We hypothesized positive change in HRQoL as a result of cataract extraction.   RESULTS. Significant improvement (p < .05) in HRQoL between baseline and 1 month follow-up was found for all indexes except the SF-6D. Mean differences ranged from 0.00 (SF-6D) to 0.06 (HUI3). Patients experienced most of their improvement by 1 month. The HUI2, HUI3 and QWB-SA were more responsive to change than the other measures. Effect sizes, defined as ((post-surgery)-(pre-surgery))/SD ranged from -0.03 for the SF-6D to 0.27 for the HUI3. Tests of subcomponent responsiveness suggested that the change was best captured by the HUI2, HUI3 and QWB because they have sensory components or ask specifically about vision. Among all measures, the largest effect size was noted for the VFQ-25 (0.67). The generic measures were about equally correlated (around r=0.50) with the total VFQ score.   CONCLUSIONS. Five preference-based measures of HRQoL yielded different estimates of change following cataract surgery. Most of the measures captured change, but the estimated QALY changes were not interchangeable. Differences in sensitivity to change in cataract patients may be related to the differing content of the measures. Estimates of quality-adjusted life years (QALYs) associated with clinical treatments may be influenced by choice of measure.