Outcomes measurement: health-related quality of life.

Outcomes research is rapidly expanding and evolving in the assessment of medical treatment and has significant potential contributions to the assistive technology field. Over the past two decades, numerous instruments have been developed and are widely used to collect data for evaluating the efficacy and effectiveness of traditional medical interventions. Although this methodology may not transfer seamlessly to assistive technology, the basis of its instrumentation and many of its concepts are highly relevant. Many current and emerging medical and assistive technology interventions are vigorously advocated but have inadequately demonstrated their positive impact on outcome. A key concept used in medical technology outcomes measurement is health-related quality of life, which represents the functional effect of an illness and its consequent therapy as perceived by the individual receiving treatment. People tend to make decisions about alternative health care services by estimating the effects of an intervention on outcomes important to themselves, by comparing intervention benefits and harms and by deciding whether the outcomes are worth the costs. Numerous valid, reliable, and responsive health-related quality of life instruments are available and are designed to discriminate between individuals, to evaluate change over time, or to predict outcome. Many are worth examining for potential use or adaptation in assistive technology outcomes measurement. Some of these instruments are generic, some specific, and others deal with health state preference. Generic health-related quality of life instruments are broadly applicable across various diseases, conditions, or populations. Specific instruments focus on a given disease, condition, or population. Health state preference instruments assess an individual's desirability for a given health state or outcome. Assistive technology practitioners claim that they improve the quality of life for the individuals they serve. Health-related quality of life must then be considered an integral component of the evaluation of service effectiveness. This paper reviews the concepts and instrumentation used in medical technology assessment for consideration and potential application in assistive technology measurement.