To examine the efficacy of dexamethasone sodium phosphate (DEX) iontophoresis for the treatment of rheumatoid arthritis (RA) of the knee, and to obtain statistical information for a future randomized controlled trial (RCT).
Ten subjects with RA, ranging in age from 34-75, were randomly assigned to either the experimental or placebo group. Iontophoresis treatments were given to both groups on days 1, 3, and 5. Five subjects in the experimental group received a mixture of 1 ml of DEX (4 mg/ml) and 1 ml of injectable sterile water; those in the placebo group received 2 ml of saline solution. Pain on movement, at rest, and on pressure, active joint count, and active range of motion, were evaluated on days 1, 5, and 20. The patient's global assessment of treatment efficacy was also assessed on days 5 and 20. Mann-Whitney U tests and Friedman two-way analyses of variance were performed for statistical analyses.
Pain at rest was found to be statistically different between the two groups (P = 0.0317). Statistical significance was also found over time for pain on movement within the experimental group (P = 0.0224).
The results suggest that DEX iontophoresis is more effective than placebo in relieving pain at rest and on movement in the RA knee. Based on the study data, a total of 40 subjects will be required for an RCT of a similar nature.