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Am Fam Physician. 2003;68(1):155-158

Clinical Question: Is steroid iontophoresis effective in the short-term treatment of lateral epicondylitis?

Setting: Outpatient (any)

Study Design: Randomized controlled trial (double-blinded)

Synopsis: In this double-blind randomized controlled trial, patients with symptoms of tennis elbow for less than three months were assigned (masked allocation) to receive iontophoresis (ultrasonography accompanied by topical dexamethasone in a dosage of 2.5 mL of 0.4 percent injection solution; n = 99) or identical placebo (n = 100) every one to three days for a total of six treatments.

The main outcome of interest was a global evaluation by the examiner and the patient's pain rating on a visual analog scale. The examiner's visual analog scale rating and the patient's global evaluation also were assessed. It is unclear if the global rating scales were based on validated instruments, and the researchers do not state whether they used an intention-to-treat approach to their analysis.

At baseline, more patients in the placebo group had been splinted before study enrollment. The visual analog scale ratings improved in both groups of patients, although those treated with dexamethasone had slightly better relief (23-mm improvement on a 100-mm scale) than patients who were treated with placebo (14-mm improvement). Although this 9-point difference was statistically significant, the minimum clinically important difference is usually 15 to 20 mm.

The examiner's global assessment, the outcome with perhaps the greatest external subjectivity and based on the least valid means of assessment, was improved in 52 percent of patients treated with dexamethasone compared with 33 percent of those treated with placebo. The authors do not mention if there was more than one clinical assessor or whether the same persons did the baseline and post-treatment evaluations. These latter points are important because the study was sponsored by the manufacturer of the machines used in the study. At one month after treatment, no significant differences were evident in any patient-oriented outcomes.

Bottom Line: In patients with tennis elbow lasting less than three months, steroid iontophoresis resulted in clinically insignificant improvements in pain two days after the conclusion of treatment when compared with placebo. No differences were noted in any patient-oriented outcomes one month after the conclusion of treatment. (Level of Evidence: 2b)

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