Cryotherapy versus salicylic acid for the treatment of plantar warts (verrucae): a randomised controlled trial

Abstract

Objective To compare the clinical effectiveness of cryotherapy versus salicylic acid for the treatment of plantar warts. Design A multicentre, open, two arm randomised controlled trial. Setting University podiatry school clinics, NHS podiatry clinics, and primary care in England, Scotland, and Ireland. Participants 240 patients aged 12 years and over, with a plantar wart that in the opinion of the healthcare professional was suitable for treatment with both cryotherapy and salicylic acid. Interventions Cryotherapy with liquid nitrogen delivered by a healthcare professional, up to four treatments two to three weeks apart. Patient self treatment with 50% salicylic acid (Verrugon) daily up to a maximum of eight weeks. Main outcome measures Complete clearance of all plantar warts at 12 weeks. Secondary outcomes were (a) complete clearance of all plantar warts at 12 weeks controlling for age, whether the wart had been treated previously, and type of wart, (b) patient self reported clearance of plantar warts at six months, (c) time to clearance of plantar wart, (d) number of plantar warts at 12 weeks, and (e) patient satisfaction with the treatment. Results There was no evidence of a difference between the salicylic acid and cryotherapy groups in the proportions of participants with complete clearance of all plantar warts at 12 weeks (17/119 (14%) v 15/110 (14%), difference 0.65% (95% CI -8.33 to 9.63), P=0.89). The results did not change when the analysis was repeated but with adjustment for age, whether the wart had been treated previously, and type of plantar wart or for patients' preferences at baseline. There was no evidence of a difference between the salicylic acid and cryotherapy groups in self reported clearance of plantar warts at six months (29/95 (31%) v 33/98 (34%), difference -3.15% (-16.31 to 10.02), P=0.64) or in time to clearance (hazard ratio 0.80 (95% CI 0.51 to 1.25), P=0.33). There was also no evidence of a difference in the number of plantar warts at 12 weeks (incident rate ratio 1.08 (0.81 to 1.43), P=0.62). Conclusions Salicylic acid and the cryotherapy were equally effective for clearance of plantar warts. Trial registration Current Controlled Trials ISRCTN18994246, National Research Register N0484189151. INTRODUCTIONVerrucae (or plantar warts) are extremely common, being experienced by most people at some time during their lives. Studies that have examined the prevalence of warts or verrucae have produced a wide range of estimates-from 0.84% in the US, 1 3.3% to 4.7% in the UK, 2 3 and up to 24% in 16-18 year olds in Australia.

British Association of Dermatologists' guidelines for the management of cutaneous warts 2014

“…Neither treatment seemed particularly effective for plantar warts. A lack of effectiveness of both SA and cryotherapy for treating plantar warts is also corroborated by data from the trial of Cockayne et al 12 This involved 240 patients with plantar warts treated in U.K. podiatric practices, with either SA 50% for 12 weeks or 'gentle' cryotherapy (up to four treatments delivered by spray or probe usually with prior paring of overlying skin). There was neither a placebo nor a no-treatment group, and both treatments achieved a modest cure rate of only 14%.…”

“…In contrast, placebo had a cure rate of 23% (range 5-73%). 10 Two important trials published within the last few years 11,12 are included in a recently updated Cochrane review. 13 Bruggink et al 11 studied 250 patients in primary care who were randomized to one of three treatment regimens: SA 40% ointment, fortnightly cotton-bud cryotherapy, or no treatment for 13 weeks.…”

“…10 Where possible, subgroup analysis of data from these trials suggests that cure rates are generally better for hand warts than for plantar warts. Two recently published trials 11,12 have provided much betterquality data than previously and have compared cryotherapy directly with SA. 13 As discussed in the section on SA (section 8.2.1.a.…”

Treatments for common and plantar warts

“…d3271), Cockayne and colleagues compare the effectiveness of cryotherapy versus salicylic acid for the treatment of plantar warts. 4 Treatments have been based on destruction (cryotherapy, photodynamic treatment, pulsed dye laser), keratolysis (salicylic acid), immunostimulation (dinitrochlorobenzene, interferons), or antimitotic effects (bleomycin, fluorouracil). 1 5 A systematic review of topical treatments for cutaneous warts was published in 2006 and updated in 2009 to include subsequent randomised controlled trials.…”

“…8 Cockayne and colleagues' study investigated 240 patients aged 12 years or more with plantar warts. 4 In one group of patients, a healthcare professional delivered cryotherapy using liquid nitrogen two to three weeks apart for a maximum of four treatments. This treatment was compared with daily self treatment with 50% salicylic acid for a maximum of eight weeks.…”