Limited healthcare dollars have resulted in insistence that the benefit of new therapies be evaluated before being approved for marketing or reimbursement under health service systems. Adequate evidence of a treatment's effectiveness includes evidence of impact on patient's health-related quality of life, including physical, mental, and emotional health. There are two types of measures of health-related quality of life. One, general health and utility measures, inquire about health in a broad sense, and can be applied and compared across many situations. The second type, specific measures, addresses narrower aspects of life related to a specific problem, function, or manifestations of an underlying disease process. Results of studies focusing on health-related quality of life only will be useful if the measurement instrument is valid and capable of detecting important change. Investigators should make a good choice of measurement instrument, and then ensure their study design will yield valid results. We offer basic guidelines for the measurement of health-related quality of life as an outcome in clinical research. This discussion addresses clinicians, who are making decisions regarding the relevance of study results, and investigators who are designing studies.
