Validating the Functional Pain Scale for Hospitalized Adults.

BACKGROUND: Enhancing pain patient's ability to function and cope is important, but assessing only intensity ignores those aspects of pain. The Functional Pain Scale (FPS), addresses these dimensions but lacked validation in hospitalized adults with chronic pain. AIMS: This research was conducted to establish the FPS psychometric properties in hospitalized adults. DESIGN: A prospective pilot study examined the reliability and validity of the FPS in two acute care hospitals. SETTINGS: Adult inpatients from medical/surgical units at two hospitals. PARTICIPANTS/SUBJECTS: A convenience sample of 93 subjects from an Academic Medical Center and 51 from a tertiary care hospital who were 21-81 years old and primarily Caucasian. METHODS: Hospitalized adults with chronic pain at two facilities provided pain scores from the FPS, Numeric Rating Scale, Pain, Enjoyment of Life, and General Activities Scale, and Quality of Pain Care Scale. Test-retest reliability and construct validity were evaluated using standard correlation methods. RESULTS: Hospitalized adults aged 21-88 years with chronic pain (N = 144) were evaluated. Data supported test-retest reliability of the FPS (r = .84; p < .001), which had strong, statistically significant correlations with the Numeric Rating Scale at different study sites (r = 0.75 and r = 0.45, respectively), indicating acceptable construct validity. Significant weak correlations between the FPS and other measures of mood and functioning failed to support discriminant validity. CONCLUSIONS: Although statistically significant, the reliability and validity of FPS were not as strong in hospitalized chronic pain patients as reported for older adults in other settings.