Objectives: The purpose of this study was to develop a patient-centered measure of treatment preference applicable across a range of diseases and treatment decisions.
Methods: Instrument development was based on previous research supplemented by open-ended interviews and focus groups. Psychometric properties of the instrument were determined by administration to 125 persons aged 60 or older with a limited life expectancy secondary to congestive heart failure, chronic obstructive pulmonary disease, or cancer. Test-retest and inter-rater reliability were established using intraclass correlation coefficients. Construct validity was established by examining associations of the measure with a single-item question regarding treatment goals and with age, ethnicity, and functional impairment, characteristics known to be associated with preferences. The Willingness to Accept Life-Sustaining Treatment instrument (WALT) consists of 6 scenarios in which respondents weigh treatment burden against treatment outcomes expressed in terms of the likelihood of different health states and length of life following treatment.
Results: Inter-rater reliability ranged from .73 to .95 and test-retest reliability from .49 to .93. WALT scores were significantly associated with a simpler measure of preference and with age, ethnicity, and functional impairment.
Conclusions: The WALT measures patients' treatment preferences, assessed in the context of treatment burden and multiple aspects of treatment outcome with sound psychometric properties.