Quality of Well-Being Scale (QWB)

Overview

The first version of the QWB was developed in the 1970s by J. W. Bush and his colleagues at the University of California at San Diego. It was later refined to its current forms in the late 1990s by Robert M. Kaplan. The QWB is a general health-related questionnaire that measures quality of life as defined by four major domains-symptoms, mobility, physical activity, and social activity. Scores from the questionnaire are often translated into an economic assessment for studies of cost-effectiveness of treatment and also to approximate an individual's QALY. The QWB exists in two formats-self-administered (QWB-SA) or given by a trained interviewer, often a healthcare provider. Each type of QWB takes about 20 minutes to complete. The QWB has been translated into Spanish, German, Chinese, and many other languages.

Scoring

In terms of finding a person's place on the scale, the QWB combines weighted values for symptoms and functioning. Functioning is evaluated by questions that gather information about limitations over the previous 3 days, within three areas-mobility, physical activity, and social activity. In addition, symptoms are evaluated by asking simple questions about how the individual feels with regard to the presence or absence of common symptom complexes (e.g., sore throat, joint pain). The scores (which are arranged in a roughly normal distribution) from these four areas are tallied

to provide a numerical evaluation of an individual's well-being at a given point in time, somewhere on the continuum between the extremes of death (0.00) to complete health (1.00). In addition to using morbidity descriptors, the QWB also uses mortality data from life tables, clinical experience, and direct measurement to help determine quality-adjusted life expectancy (current life expectancy corrected for decreased quality of life associated with disabilities and disease states).

Validity and Reliability

Many research studies have shown the QWB to be very reliable (consistency of measurement) in the short term, especially when it is given on back-to-back days, with a 96% reliability rate in the general adult population and ranging from 83% reliability in burn patients to 98% reliability in chronic obstructive pulmonary disease (COPD) patients, when considering the population with morbidities. Many studies have also shown the QWB to be highly valid (correctness of measurement) in repeated randomized controlled trials (RCTs). One study, for example, found that individuals with Alzheimer's disease scored significantly lower on the QWB, while the degree of cognitive impairment was also found to be related in a systematic way, leading to lower QWB scores. Another study found that the QWB scores were highly correlated with performance and physiological findings relevant to the health status of those with COPD. At the same time, the QWB was capable of being translated into well-year units for studies of cost-effectiveness and also served as an outcome predictor and measure for the disease.

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