The effectiveness of salicylic acid plasters compared with 'usual' scalpel debridement of corns: a randomised controlled trial

Background
Corns are a common foot problem and surveys have indicated that between 14-48% of people suffer from them. Many of these will seek podiatry treatment, however there is little evidence to indicate which current treatments provide long term resolution. This study compared `usual? treatment (enucleation with a scalpel) with the application of 40% salicylic acid plasters to corns to investigate which is the most effective in terms of clinical, economic and patient-centred outcomes.

Methods
A parallel-group randomised controlled trial was carried out in two centres where adults who presented with one or more corns and who met the inclusion criteria were allocated to either `usual? scalpel debridement or corn plaster treatment. All participants had measurements of corn size, pain using a 100?mm visual analogue scale (VAS) and health-related quality of life (EQ-5D) measures by an independent podiatrist, blind to treatment allocation at baseline, 3, 6, 9 and 12?months.

Results
202 participants were randomised to receive scalpel debridement or corn plaster treatment (101 in each group). At 3?months 34% (32/95) of corns had completely resolved in the corn plaster group compared with 21% (20/94) in the scalpel group (p?=?0.044), and 83% (79/95) had reduced in size in the corn plaster group compared with 56% (53/94) in the scalpel group (p?<?0.001). At 12?months, time to corn recurrence was longer in the corn plaster group (p?<?0.001). Pain from the corns was significantly lower in the corn plaster group at 3?months (p?<?0.001) and EQ-5D scores changed (improved), from baseline, by 0.09 (SD ?0.31) and 0.01 (SD ?0.25) points in the corn plaster and scalpel groups respectively (p?=?0.056). By month 12, EQ-5D scores had changed by 0.12 and ?0.05 in the corn plaster and scalpel groups respectively (p?=?0.005). The EQ-5D, VAS scores and the four domains of the Foot Disability Scale were similar in both groups at 3 and 12?months. The economic analysis indicated that corn plasters were a cost effective intervention.

Conclusions
The use of corn plasters was associated with a higher proportion of resolved corns, a prolonged time to corn recurrence, less pain and reduced corn size over the first 6?months in comparison with `usual? scalpel treatment and this intervention was cost effective. Used under supervision of a podiatrist on appropriate patients, corn plasters offer an effective alternative to scalpel debridement.