The Patient-Specific Functional Scale: Validity in Workers' Compensation Claimants

Abstract

Gross DP, Battié MC, Asante AK. The Patient-Specific Functional Scale: validity in workers' compensation claimants. Objective To examine the construct and predictive validity of the Patient-Specific Functional Scale (PSFS) in workers' compensation claimants. Design Prospective cohort study with 1-year follow-up. Setting A workers' compensation rehabilitation facility. Participants Subjects included 294 claimants with a variety of musculoskeletal disorders. The sample was predominantly male (70%), with a mean age of 44 years. Subjects completed a battery of measures at baseline including the PSFS, the Pain Disability Index (PDI), and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36). Interventions Not applicable. Main Outcome Measures Outcomes for determining predictive validity included administrative indicators of timely return to work and recovery during the 1-year follow-up. Analysis included Pearson correlation and multivariable Cox and logistic regression. Results At baseline, the PSFS correlated moderately ( r range, 0.3−0.5) with other indicators of functional limitation (PDI, SF-36 role−physical subscale) but negligibly with the SF-36 mental health and role−emotional subscales. The PSFS was associated with timely recovery (adjusted hazard ratio, 1.16; 95% confidence interval, 1.07–1.27) with increasing functional limitation related to delayed recovery. Conclusions Results provide construct and predictive validity evidence for the PSFS as an indicator of functional limitation in workers' compensation claimants.