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.