Reproducibility of improvements in patient-reported functional ability following functional capacity evaluation

Background Performance of functional capacity evaluation (FCE) may affect patients, self-efficacy to complete physical activity tasks. First evidence from a diagnostic before-after study indicates a significant increase of patient-reported functional ability. Our study set out to test the reproducibility of these results. Methods Patients with musculoskeletal trauma and an unclear return to work prognosis were recruited in a trauma rehabilitation center in Lower Austria. We included patient cohorts of three consecutive years (2016: n = 161, 2017: n = 140; 2018: n = 151). Our primary outcome was patient-reported functional ability, measured using the Spinal Function Sort (SFS). SFS scores were assessed before and after performing an FCE to describe the change in patient-reported functional ability (cohort study). We investigated whether the change in SFS scores observed after performing an FCE in our first cohort could be replicated in subsequent cohorts. Results Demographic data (gender, age and time after trauma) did not differ significantly between the three patient cohorts. Correlation analysis showed highly associated before and after SFS scores in each cohort (2016: r(s) = 0.84, 95% CI: 0.79 to 0.89; 2017: r(s) = 0.85, 95% CI: 0.81 to 0.91; 2018: r(s) = 0.86, 95% CI: 0.82 to 0.91). Improvements in SFS scores were consistent across the cohorts, with overlapping 95% confidence intervals (2016: 14.8, 95% CI: 11.3 to 18.2; 2017: 14.8, 95% CI: 11.5 to 18.0; 2018: 15.2, 95% CI: 12.0 to 18.4). Similarity in SFS scores and SFS differences were also supported by non-significant Kruskal-Wallis H tests (before FCE: p = 0.517; after FCE: p = 0.531; SFS differences: p = 0.931). Conclusions A significant increase in patient-reported functional ability after FCE was found in the original study and the results could be reproduced in two subsequent cohorts.