Influence of the physical environment on treatment effect in exercise therapy for knee or hip pain

Context effects are defined as the effects of a given treatment, not directly caused by the treatment itself, but, rather, caused by the context in which the treatment is delivered. The patient-practitioner relationship is a known context factor, but it is hard to standardize across health-care settings. The physical environment is easier to standardize and may act as a context factor and influence treatment outcomes. Studies from hospital environments have shown that the physical environment influences health outcomes, patients, and clinicians. It is unknown if the physical environment affects treatment outcomes in other health-care settings, such as rehabilitation and exercise therapy settings. The aim of this thesis was to investigate the role of the physical environment as a contributor to context effects in the treatment response from exercise therapy as treatment for muskuloskeletal pain. In a randomised controlled double-blind trial (RCT), 103 participants were randomised in a 2:2:1 allocation to three groups: 1) 42 participants exercised in a contextually enhanced environment, 2) 40 participants exercised in a standard environment, and 3) 21 participants were on a passive waiting list. Middle-aged individuals reporting persistent knee or hip pain within the past three months were eligible to participate. Eight weeks of group-based neuromuscular exercise therapy, supervised by the same therapists, was performed in either a newly built contextually enhanced environment or in a standard old, unenhanced environment. The passive waiting list group received no exercise therapy prior to the eight-week follow-up. Both participants and the supervising therapists were blind to the study aim. Participants self-reported joint pain on an 11-point numerical rating scale (NRS) before and after each exercise session. The primary endpoint was participants’ global perceived effect (GPE) assessed on a 7-point Likert scale at the eight-week follow-up. A qualitative study was nested into the RCT including six semi-structured focus-group interviews with participants (n=25) and individual interviews with therapists (n=2) exploring experiences and perceptions of the physical environments. The waiting-list group reported no significant improvement (-0.05 GPE, CI 95% -0.5 to 0.4). Contrary to the study hypothesis, participants exercising in the standard environment reported greater improvement in GPE (0.98, CI 95% 0.5 to 1.4) than participants exercising in the contextually enhanced environment (0.37, CI 95% -0.2 to 0.9), p=0.07.Patient-reported secondary outcomes and qualitative findings similarly favoured exercise in the standard environment over exercise in the contextually enhanced environment. In interviews, participants from the standard environment stated that they felt at-home, experienced a strong sense of fellowship, and identified their own body image with the standard environment. The mean age of the study population was 58.5 years, 63% had knee pain as primary complaint, 61% were women and 88% reported joint pain for more than one year. As expected, participants attending neuromuscular exercise therapy reduced their joint pain over time with 0.04 NRS (95% CI 0.02 to 0.05, p<0.01) per exercise session. Similarly, the size of their acute exercise-induced pain flare decreased 0.04 NRS (95% CI 0.03 to 0.05, p<0.01) per exercise session. The results of this study indicate that the physical environment does influence treatment effects from exercise therapy, suggesting that the physical environment contributes to context effects. Matching the physical environment in exercise therapy to the preferences of the intended users may enhance self-reported treatment effects. Furthermore, the study results support previous research that neuromuscular exercise therapy provides pain relief for individuals with persistent knee or hip pain.