Predictive factors in poor inter-rater reliability among physical therapists

Manual therapy is a widely used form of treatment among physical therapists and has been shown to be effective in the treatment of musculoskeletal disorders. In numerous studies, the reliability of clinicians performing the four grades of mobilization of manual therapy has been poor. A sample of 23 licensed physical therapists participated in quasi-experimental repeated measures designed to determine if predictive factors such as gender or years of experience contribute to inter-rater reliability variances. In this design, therapists performed Grade I, II, III and IV mobilizations on two asymptomatic volunteers at the level of L3, based on resistance defined Grades of Movement. The Kistler Force Plate ™ was used to record mobilization forces for each physical therapist at a rate of 600 data-point measurements per second. Data were assessed to determine if poor inter-rater reliability is reflective of certain predictive variables. The results identified that the independent variables of age, years of experience, gender, frequency of use, education, and background of the rater did not contribute to the overall variance within the study. Further investigation is required as to what determines the poor inter-rater reliability of spinal accessory mobilizations by practicing clinicians.