Psychometric properties of a single-item visual analog scale measuring goals of care in patients with advanced cancer.

PURPOSE

The purpose of this study was to examine the psychometric properties of a single-item visual analog scale (VAS) to measure goals of care in patients with advanced cancer.

METHODS

Data were obtained from 378 patients with diagnoses of advanced lung, gastrointestinal, or pancreatic cancer. Goal of care was measured at baseline and every 3 months until patient death or completion of the 15-month study period. A single-item VAS ranging from 0 (quality of life is all that matters) to 100 (length of life is all that matters) was used to measure patients' goals of care for all study subjects; a subsample of subjects also completed the Quality of Life-Length of Life scale which asked patients to select categories of preferences. Test-retest reliability (intra-class correlation) and construct validity (known-groups, convergent, divergent) were evaluated.

RESULTS

At 9 and 12 months, the test-retest reliability for patients with stable symptoms (n = 107) was established with the ICC = 0.81, p < .001. Known-groups (r = 0.99, p < .001), convergent (r = 0.78, p < .001), and divergent (r = .06, p = 0.24) validity all demonstrated evidence of good construct validity.

CONCLUSIONS

Preliminary psychometric testing for a single-item VAS that measures goals of care in a sample of patients with advanced cancer met standard requirements for reliability and validity. While further testing with a larger sample size is recommended, the tool's use in the clinical area to assess cancer patients' goals of care is appropriate. Such a tool could facilitate goals of care discussions in the clinical area.