Application and interpretation of simple odds ratios in physical therapy-related research

Over the past several decades, physical therapists have demonstrated an increasing responsiveness to the profession's obligation to generate objective evidence for examination and intervention strategies employed in physical therapy practice. This trend is evident, not only in the increasing number of journals that are publishing physical therapy research, but in the growing sophistication of research design and analytic options used by investigators. At the same time, physical therapists are held increasingly accountable for adopting an evidence-based approach to practice. The result for many of us is a growing concern about our ability to interpret study findings. The ability to independently weigh the importance to our own practice of evidence reported in a study requires that we understand the strengths and potential weaknesses of the sample, design, and analyses being used. The odds ratio (OR) is one of the analytic measures that has only recently appeared in the physical therapy literature. Because the OR may be unfamiliar to physical therapists, the goal of this paper is to provide a description of the simple OR and a discussion of its uses, interpretation, and potential limitations.