Risk factors for recurrence after successful treatment of warts: the role of smoking habits

Background: Several therapies have been proposed for cutaneous warts without results concerning factors affecting recurrences. Objective: To determine the importance of individual characteristics and different therapy modalities in the occurrence of relapses. Methods: Observational prospective cohort study including 199 patients affected by multiple plantar warts treated as follows: 49 with keratolytics, 50 with CO2 laser, 50 with pulsed dye laser (PDL) and 50 with cryotherapy. Personal data were evaluated through a questionnaire, and treatment information was collected. A Cox regression analysis was performed to identify independent factors for relapse occurrence. Results: Of patients, 57.8% showed a persistent clearance of warts after treatment with a higher recurrence-free interval when treated with PDL. Accordingly, the risk of recurrence was increased with CO2 laser [hazard ratio (HR) 2.92, 95% confidence interval (CI) 1.49–5.74] and keratolytic treatment (HR 3.23, 95% CI 1.60–6.54), as compared to PDL. Furthermore, the multivariate analysis highlighted a higher risk of recurrence in patients between 26 and 35 years (HR 1.88, 95% CI 1.03–3.45), older than 35 (HR 2.23, 95% CI 1.23–4.07) and smokers (HR 4.90, 95% CI 3.09–7.78). Conclusions: Pulsed dye laser is characterized by the lowest rate of recurrence. Furthermore, our study highlights that the risk of warts relapse is 5-fold higher in smokers compared to non-smokers, revealing the importance of the effects of smoking on inflammation and immune response.