Sensitivity and Specificity of the Indicators of Sincere Effort of the EPIC Lift Capacity Test on a Previously Injured Population. M. Jay, J. Lamb, R. Watson, I. Young, F. Fearon, J. Alday, A. Tindall. Spine, 25(11), 1405-1412.
PubMed ID: 10828923
This study examined indicators of sincere effort in the EPIC lift capacity test. Indicators included percent increase in heart rate, percent increase in systolic blood pressure, score on the Spinal Function Sort or Hand Function Sort, and evaluator’s subjective evaluation of the subject’s physical exertion during the test.
Subjects were volunteers who had previously been diagnosed with musculoskeletal pathology. This study used a randomized control posttest only design with five blinded experienced evaluators who were certified in the use of the EPIC lift capacity test. Forty-one subjects were randomly assigned into one of two groups. The control group received standardized pretest instructions to perform to maximum effort. The experimental group received standardized pretest instructions to perform at 50 percent of their perceived maximum effort. Aside from this change based on group participation, the EPIC lift capacity protocol was followed, including testing across all six subtests.
Inter-rater reliability was assessed through the use of an intraclass correlation coefficient of the evaluators’ ratings of each participant’s overall effort level. This resulted in a correlation coefficient of r = .834 based on evaluator agreement of the participant’s overall effort.
Validity in terms of accuracy of identifying overall effort was found to be 86.8 percent, with indicators of valid effort having a positive predictive value of 94.4 percent and a negative predictive value of 80.0 percent. Indicators of valid effort were found in a multiple regression analysis to account for 94.9 percent of the total variance in the determination of effort level. Most of this variance was accounted for by the evaluator’s indication of effort, with responses to the Spinal Function Sort or Hand Function Sort contributing a small percent and the heart rate and systolic blood pressure changes contributing negligibly.
This study supports the use of the EPIC lift capacity test’s indicators of valid effort. These indicators’ high positive predictive value and high negative predictive value make them very useful for clinicians. The best single indicator of valid effort was the experienced clinician’s evaluation of effort according to observational criteria.
Based on the results of this study, the investigators recommend that heart rate response of less than 25 percent increase is considered as an indicator of less than maximum effort, and a 50 percent increased heart rate response should be considered as a definitive threshold for sincere effort.
This study provides evidence supporting the use of the EPIC lift capacity test’s indicators of sincere effort. The authors describe this as critical to substantiate the trained evaluator’s assessment of effort, often a contentious aspect of these evaluations.