Construct validity of a kinesiophysical functional capacity evaluation administered within a worker's compensation environment

The construct validity of a kinesiophysical Functional Capacity Evaluation (FCE) administered within a worker's compensation context was examined. A cross-sectional study design was employed. Clinical and demographic information on workers' compensation claimants was extracted from a rehabilitation facility's database. Measures of interest were the Isernhagen Work Systems' (Duluth, MN) FCE, the Pain Disability Index (PDI), and a pain visual analogue scale (VAS). A multitrait Pearson correlation matrix was created to observe the pattern of relationships between variables. The sample consisted of 321 subjects with work-related, medically stable low back pain of median duration of 307 days. FCE performance was moderately correlated with the PDI (r=-0.44-0.52) and with the pain VAS (r=0.34-0.45). Pain intensity was correlated highly with the PDI (r=0.79). The moderate relationship between FCE and the PDI supports the construct validity of FCE as a functional measure. However, kinesiophysical FCE performance was not unrelated to pain severity ratings as purported.