HPV type in plantar warts influences natural course and treatment response: secondary analysis of a randomised controlled trial.

ABSTRACT

BACKGROUND: Cryotherapy is effective for common warts, but for plantar warts available treatments often fail. OBJECTIVES: Within a pragmatic randomised controlled trial, we examined whether subgroups of common and plantar warts have a favourable natural course or response to treatment based on wart-associated HPV type. STUDY DESIGN: Consecutive patients with new common or plantar warts were recruited in 30 Dutch family practices. Patients (n=250) were randomly allocated to liquid-nitrogen cryotherapy, 40% salicylic acid self-application, or wait-and-see policy. Before treatment, swabs were taken from all separate warts and analysed by a broad spectrum HPV genotyping assay. At 13 weeks, cure rates with 95% confidence intervals of common and plantar warts on intention to treat basis were compared between treatment arms for the different wart-associated HPV types. RESULTS: In total, 7% of swabs tested negative for HPV DNA and 16% contained multiple types, leaving 278 of 371 common swabs (75%) and 299 of 373 plantar swabs (80%) with a single type for analysis. After wait-and-see policy, cure rates were 2/70 (3%, 95% confidence interval 1-10) for HPV 2/27/57-associated common warts, 4/58 (7%, 3-16) for HPV 2/27/57-associated plantar warts, and 21/36 (58%, 42-73) for HPV 1-associated plantar warts. After cryotherapy, cure rates were 30/44 (68%, 53-80), 6/56 (11%, 5-21), and 15/23 (65%, 45-81); after salicylic acid 16/87 (18%, 12-28), 15/60 (25%, 16-37), and 24/26 (92%, 76-98), respectively. CONCLUSIONS: HPV type influenced the natural course and response to treatment for plantar warts. HPV testing potentially optimises wart treatment in primary care.