Understanding Factors that Influence Ratings of Global Perceived Effect by Rehabilitation Clinicians and Patients with Low Back Pain: A Cognitive Interview Study

Global Perceived Effect (GPE) is a self-report outcome measure used to capture a patient’s global perception of change after an intervention. It is typically assessed through a single question that asks patients to reflect on their previous and current state and rate their improvement. However, it is unclear what patients typically take into consideration when rating their change as well as additional factors that may influence their responses. We will conduct cognitive interviews with rehabilitation service users and providers. Participants will be included if they are a) physiotherapists or chiropractors who treat patients with chronic low back pain, or b) persons with chronic low back pain who attended at least 4 exercise therapy sessions. All participants will rate their GPE using an 11-point numeric rating scale after their last therapy session during an interview using Think Aloud (TA) and Verbal Probing (VP) methods. We will use qualitative content analysis for the exploration and interpretation of cognitive interview data. The overall objective of this study is to gain an in-depth insight into what patients with low back pain and rehabilitation professionals (physiotherapists and chiropractors) take into consideration when completing the GPE and how they recall their overall health. Specifically, our goal is to consider the content validity of the GPE metric using qualitative analysis methods to categorize and describe patterns of reported considerations influencing ratings, and to explore what underlying factors may influence GPE scale responses from the patients’ and therapists’ perspectives.