Critical review of the international assessments of health-related quality of life.

This paper reviews the international adaptation and use of generic health quality of life measures over the last several years, including the Nottingham Health Profile (NHP) the Sickness Impact Profile (SIP), the Medical Outcomes Short-Form 36 (MOS SF-36), the EuroQol, and Dartmouth COOP Charts. International work with disease or condition specific HRQL measures is exemplified with the European Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLQ), and the Spitzer Quality of Life (QL) Index. Progress towards cross national measurement equivalence in HRQL measures reported in the literature has been uneven. Results show that the development of language-adapted versions of HRQL measures to date have mostly concerned translation issues, within the context of independently conducted studies. Substantially less focus has been placed on psychometric equivalence across language versions necessary for coordinated international studies, such as multi-national clinical trials. However, this picture is rapidly changing with recent projects underway to develop and refine new or existing HRQL measures. Overall, the lack of prominent differences found between countries in ranking of health states in major HRQL measures supports the feasibility of developing internationally applicable HRQL instruments. Recommendations are made for additional data needed to better ascertain the degree of measurement equivalence developed in the various versions of each instrument reviewed.