A REVIEW OF THE PROGRESS TOWARDS DEVELOPING HEALTH-RELATED QUALITY-OF-LIFE INSTRUMENTS FOR INTERNATIONAL CLINICAL-STUDIES AND OUTCOMES RESEARCH

This article reviews the international adaptation and use of generic h ealth-related quality-of-life (HRQL) measures over the last several ye ars. It focuses, as examples, on the Nottingham Health Profile (NHP), the Sickness Impact Profile (SIP), the Medical Outcomes Study Short-Fo rm 36 Item Health Survey (MOS SF-36), the EuroQoL, Dartmouth Primary C are Cooperative Information Project (COOP) chart system, the European Organization for Research and Treatment of Cancer (EORTC) Quality of L ife Questionnaire (QLQ) and the World Health Organization's WHOQOL, Th ese instruments exemplify several different models for developing or a dapting HRQL measures described in the literature, each model choosing unique approaches to the process of validation for cross-national use . There has been considerable scientific activity in recent years aime d at advancing the capabilities for international HRQL assessments. Wh ereas prior adaptation work was focused exclusively on translation iss ues, recent work has begun to rely on common methodology for translati on and validation of key measurement properties across language versio ns. Although the major HRQL measures reviewed have not yet reached the point at which there is sufficient evidence for measurement equivalen ce across different language versions, internationally coordinated pro jects are planned and under way for these instruments to advance and r efine this capacity. Preliminary evidence suggests that there are bo f ew prominent differences between countries in ranking of health states that are representative of major HRQL dimensions, and in the levels o f impact of illnesses on well-being within those dimensions. Future st udies should collect additional psychometric data to moi-e fully quant ify measurement equivalence among the various language versions in whi ch each instrument is available. Additionally, more work is required t o address cultural differences within nations or language groups.