Patient expectations assessed before randomisation and after the first treatment session, and their associations with pain outcome at 3 months in patients with tennis elbow: a secondary analysis of a randomised controlled feasibility trial in Norwegian secondary care.

Abstract

To evaluate patients' expectations of pain improvement before randomisation (T₁) and after the first treatment (T₂), and to examine how expectations at these two time points were associated with pain outcome measured at 3 months (T₃). Exploratory secondary analyses of a three-arm, randomised controlled feasibility trial in patients with tennis elbow comparing heavy slow resistance training, shock wave therapy and advice (1:1:1). Outpatient clinic at Oslo University Hospital. Adults with lateral epicondylalgia, commonly known as tennis elbow. Expected pain was rated on a Numeric Rating Scale (NRS, 0-10) at T₁ and T₂. Present pain (NRS, 0-10) was reported at 3 months (T₃). Changes in expectations from T₁ to T₂ were summarised descriptively. Univariable linear regressions assessed associations between T₃ pain and expectations at T₁ and T₂, treatment group and baseline factors. Explained variance was quantified by R². Multivariable models including demographics and baseline pain were evaluated via adjusted R². Fifty-four participants were included. In the shock wave group, nine (47%) came to expect greater improvement from T₁ to T₂; by contrast, in the advice group, seven (41%) expected less improvement. Expectations at T₁ were not associated with T₃ pain, whereas expectations at T₂ were positively associated with T₃ pain (b=0.61, 95% CI 0.33 to 0.89, p<0.01, R²=0.27), suggesting that higher expected pain at T₂ was associated with higher reported pain at T₃. Adding education and baseline pain increased explained variance modestly (R² from 0.27 to 0.32). In this study, expectations measured after randomisation and one treatment session were associated with pain at 3 months for patients with tennis elbow. Larger, prospectively designed studies should investigate how postrandomisation expectations relate to clinical outcomes in non-blinded musculoskeletal trials. NCT04803825.