Interferential current is effective in palmar psoriaris: an open prospective trial

Interferential current (IFC) has been shown to improve psoriasis in a small case series. So far no formal clinical trial had been conducted. As IFC is associated with slight prickling sensations a blinded study design was not feasible. Therefore, an open type prospective study was conducted with the assumption of 18% spontaneous remission rate. A response rate of 50% or less was judged as indicating no effect (hypothetical control), while 80% or more was considered as success (alternative hypothesis). In this "quasi-controlled" study 12 patients with therapy resistant palmar psoriasis received local treatment with IFC during a 12 week period. Treatment was performed at low current density in two daily sessions, each of 6 minutes duration. Erythema, scaling, induration, fissures and pustules were recorded in separate scores every 4 weeks. Response of a patient was judged positive when the total score of these criteria was reduced at least by two points at the end of treatment. After 12 weeks of treatment, 11 of 12 patients were cured or showed marked remission with the median overall score reduced by 4 points. An interim analysis was performed in order to decide whether the results had already reached significance (a < 0.05). The analysis revealed a statistically significant response rate of 90% (95% confidence interval 62-99%). These results are highly encouraging and should focus attention on this new therapy modality, which, in contrast to other treatments is not associated with side effects and discomfort.