Reliability of Clinician Rated Physical Effort Determination During Functional Capacity Evaluation in Patients with Chronic Musculoskeletal Pain

Introduction Functional capacity evaluation (FCE) can be used to make clinical decisions regarding fitness-for-work. During FCE the evaluator attempts to assess the amount of physical effort of the patient. The aim of this study is to analyze the reliability of physical effort determination using observational criteria during FCE. Methods Twenty-one raters assessed physical effort in 18 video-recorded FCE tests independently on two occasions, 10 months apart. Physical effort was rated on a categorical four-point physical effort determination scale (P(ED)) based on the Isernhagen criteria, and a dichotomous submaximal effort determination scale (S(ED)). Cohen’s Kappa, squared weighted Kappa and % agreement were calculated. Results Kappa values for intra-rater reliability of P(ED) and S(ED) for all FCE tests were 0.49 and 0.68 respectively. Kappa values for inter-rater reliability of P(ED) for all FCE tests in the first and the second session were 0.51, and 0.72, and for S(ED) Kappa values were 0.68 and 0.77 respectively. The inter-rater reliability of P(ED) ranged from κ = 0.02 to κ = 0.99 between FCE tests. Acceptable reliability scores (κ > 0.60, agreement ≥80 %) for each FCE test were observed in 38 % of scores for P(ED) and 67 % for S(ED). On average material handling tests had a higher reliability than postural tolerance and ambulatory tests. Conclusion Dichotomous ratings of submaximal effort are more reliable than categorical criteria to determine physical effort in FCE tests. Regular education and training may improve the reliability of observational criteria for effort determination.