A comparison of two primary care trials on tennis elbow: issues of external validity

N. Smidt, M.A. Lewis, E.M. Hay, D.A.W.M. van der Windt-Mens, L.M. Bouter, P.R. Croft

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    OBJECTIVE: To assess the clinical heterogeneity across two studies with respect to study population, interventions and outcome measures, and to evaluate the influence of these sources of heterogeneity on the results of the studies. METHODS: The individual patient data of two randomised controlled trials was used, both investigating the effectiveness of conservative treatments in 164 and 185 patients with a tennis elbow in primary care, respectively. Patients were allocated at random to a treatment with steroid injection, wait-and-see policy, NSAIDs, placebo tablets, or physiotherapy. Outcome measures included severity of the main complaint, inconvenience of the elbow complaints, pain during the day, elbow disability, pain-free grip strength and global improvement. All outcomes were assessed at one, six and twelve months after randomisation. RESULTS: The two study populations were similar with respect to age, gender, co-morbid neck/shoulder complaints, and baseline scores for the severity of pain. However, significant differences were observed for employment status, duration of elbow complaints, dominant side affected, previous history of elbow complaints, and use of painkillers. Local injections differed between the two studies with respect to volume, number and steroid preparation. However, after 1, 6 and 12 months, the treatment effects of steroid injections were very similar between the study populations. CONCLUSION: Despite large differences in study population at baseline, the responses to steroid injections were remarkably similar. Also the responses to other conservative interventions and the placebo treatment were very consistent, suggesting a uniform course of a tennis elbow and a lack of influence of clinical heterogeneity
    Original languageEnglish
    Pages (from-to)1406-1409
    JournalAnnals of the Rheumatic Diseases
    Issue number10
    Early online date30 Mar 2005
    Publication statusPublished - 2005

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