Preliminary validity of a daily functional status pain assessment tool

Readiness for discharge for a SCD vaso-occlusive crisis is dictated by factors far beyond pain control, including physical function/activity. We therefore designed and tested a functional status-based pain assessment questionnaire in SCD patients hospitalized with vaso-occlusive crises.

Sickle cell disease patients on a preselected nursing unit rated 10 draft Functional status-Based Pain Assessment items of activities of daily living on a five-point Likert scale (0-5) from "very easy" to "very difficult" daily on each day of their admission until discharge, at approximately the same time. Concurrently, they reported Numeric Rating Scale (0-10) pain intensity. For validation, we used exploratory factor analysis, confirmatory factor analysis, and item response theory analysis.

We analyzed 503 observations from 175 admissions of 88 patients. Half were female, the mean age was 32.1 ± 11.8 years, and the mean length of stay was 7.1 ± 6.9 days. The mean Numeric Rating Scale (6.8 ± 1.9) was inversely correlated with the mean Functional Status-based Pain Assessment (0-50) score (27 ± 8.0, r = -0.4342, P < .0001). Functional Status-based Pain Assessment item means ranged from 2.1 to 3.3. Cronbach's alpha was 0.91. Exploratory factor analysis showed that all Functional Status-based Pain Assessment items loaded on a single factor. Confirmatory factor analysis found adequate convergent and discriminant validity and showed strong fit of the model to the data. Item response theory analysis showed item discrimination ranging from 0.56 to 4.1, while difficulty ranged from -2.8 to 7.5.

The Functional Status-based Pain Assessment shows strong correlation with daily Numeric Rating Scale, is multidimensional, and demonstrates strong construct validity. It may improve assessment of SCD vaso-occlusive crisis pain and may enhance vaso-occlusive crisis discharge discussions.