Do baseline characteristics of patients with tennis elbow influence treatment effects?

Abstract

The aim of this study was to determine if subgroups of patients with tennis elbow respond differently to treatment. We used individual patient data (N=383) from two randomised controlled trials that investigated a wait-and-see policy, corticosteroid injections and physiotherapy. Outcome measures common and homogeneous to both trials were pain severity and global improvement. Subgroup analyses for previous history of elbow pain, baseline pain severity, duration of the current episode and employment status were performed at six and 52 weeks. Based on individual patient data from both trials, we found that corticosteroid injections were statistically and clinically superior at six weeks (p<.001), but significantly worse at 52 weeks compared to both wait and see and physiotherapy (p<.001). Subgroup effects were scarce and small. Patients with higher baseline pain showed no significant difference on pain outcomes between physiotherapy and wait-and-see at six weeks. It also appeared that non-manual workers who had an injection were the only work subgroup to demonstrate differential effects between injections and wait-and-see on global improvement at 52 weeks. The treatment outcomes were largely similar between trials and not different between most subgroups studied. In tennis elbow, it would appear that treatment outcomes are only minimally dependent on baseline patient characteristics, which supports the generalisability of individual trial results.