Assessing quality of life in clinical research: from where have we come and where are we going?

The term "quality of life" first surfaced in 1920, but it was not until the 1960s that it came to public notice in North America. This article describes the history of quality of life assessment, discusses its current status, and suggests challenges for the future. The development of generic measures began in the early 1970s and continues today. Disease-specific measures have also proliferated. The 1980s and 1990s saw an increase in methodological rigor, and additional emphasis on analytic approaches, interpretation of scale scores, cultural and language issues, as well as on the development of shorter measures. Future challenges include conceptualization and testing of theoretical models, further refinement of individualized measures for use in routine clinical practice, the use of computer adapted testing in quality of life assessment, and the inclusion of quality of life information in health databases.