What Really Works in Intervention? Using Fidelity Measures to Support Optimal Outcomes

A critical factor to move the field of physical therapy forward is the measurement of fidelity during comparisons of interventions. Fidelity translates as "faithfulness"; thus, fidelity of intervention means faithful and correct implementation of the key components of a defined intervention. Fidelity measurement guards against deviations from, or drift in, the delivery of a targeted intervention, a process necessary for evaluating the efficacy of rehabilitation approaches. Importantly, attention to fidelity measurement differentiates rehabilitation approaches from each other. However, earlier research comparing physical therapist interventions often reported findings without careful attention to fidelity measurement. The purpose of this paper is 2-fold: (1) to support the development of intervention-specific fidelity measures in physical therapy research as the gold standard for translating research findings to clinical practice, and (2) to describe the process of creating a multi-dimensional fidelity measurement instrument in rehabilitation intervention. Improved attention to fidelity measurement will allow the rehabilitation field to communicate interventions clearly with a direct link to outcomes and target the implementation of our improved intervention for the right patient problem with the right dose and the right ingredients at the right time.