Reliability of occupational therapists in determining safe, maximal lifting capacity

Determination of an individual's lifting capacity is an important component in Functional Capacity Evaluation, which is widely used to delineate potential for work. Despite a recent surge in the number and types of Functional Capacity Evaluations, and therefore in approaches to determining lifting capacity, there has been limited research to support the reliability and validity of their use. This study evaluated the inter-rater reliability of five occupational therapists in determining safe maximal lifting capacity using a biomechanical approach. In addition, the use of an operational definition of a safe lift was examined to determine its effect on therapists' decision-making process and therefore the reliability of their ratings. The use of an operational definition was found to significantly affect therapists' decision-making process in differentiating safe from unsafe lifts, with all raters showing highly significant improvements in their ability to determine the safety of lifts from pre- to postdefinition ratings, according to McNemar's χ ² statistic. The provision of a definition also enhanced therapists' reliability of ratings, with kappa values that ranged from 0.47 to 0.74 predefinition changing to 0.56–0.82 postdefinition. Possible explanations for the change in decision-making are discussed and the need for ongoing evaluation of procedures used in Functional Capacity Evaluation, particularly with regard to the determination of lifting capacity, are highlighted.