Background: The comparative efficacy, and cost-effectiveness, of imiquimod or podophyllotoxin cream, either alone or in combination with the quadrivalent HPV vaccine (Gardasil®, Merck Sharp & Dohme Corp., Merck & Co., Inc., Whitehouse Station, NJ, USA) in the treatment and prevention of recurrence of anogenital warts is not known.
Objective: The objective was to compare the efficacy of imiquimod and podophyllotoxin creams to treat anogenital warts and to assess whether or not the addition of quadrivalent human papillomavirus vaccine increases wart clearance or prevention of recurrence.
Design: A randomised, controlled, multicentre, partially blinded factorial trial. Participants were randomised equally to four groups, combining either topical treatment with quadrivalent human papillomavirus vaccine or placebo. Randomisation was stratified by gender, a history of previous warts and human immunodeficiency virus status. There was an accompanying economic evaluation, conducted from the provider perspective over the trial duration.
Setting: The setting was 22 sexual health clinics in England and Wales.
Participants: Participants were patients with a first or repeat episode of anogenital warts who had not been treated in the previous 3 months and had not previously received quadrivalent human papillomavirus vaccine.
Interventions: Participants were randomised to 5% imiquimod cream (Aldara®; Meda Pharmaceuticals, Takeley, UK) for up to 16 weeks or 0.15% podophyllotoxin cream (Warticon®; GlaxoSmithKlein plc, Brentford, UK) for 4 weeks, which was extended to up to 16 weeks if warts persisted. Participants were simultaneously randomised to quadrivalent human papillomavirus vaccine (Gardasil) or saline control at 0, 8 and 24 weeks. Cryotherapy was permitted after week 4 at the discretion of the investigator.
Main outcome measures: The main outcome measures were a combined primary outcome of wart clearance at week 16 and remaining wart free at week 48. Efficacy analysis was by logistic regression with multiple imputation for missing follow-up values; economic evaluation considered the costs per quality-adjusted life-year.
Results: A total of 503 participants were enrolled and attended at least one follow-up visit. The mean age was 31 years, 66% of participants were male (24% of males were men who have sex with men), 50% had a previous history of warts and 2% were living with human immunodeficiency virus. For the primary outcome, the adjusted odds ratio for imiquimod cream versus podophyllotoxin cream was 0.81 (95% confidence interval 0.54 to 1.23), and for quadrivalent human papillomavirus vaccine versus placebo, the adjusted odds ratio was 1.46 (95% confidence interval 0.97 to 2.20). For the components of the primary outcome, the adjusted odds ratio for wart free at week 16 for imiquimod versus podophyllotoxin was 0.77 (95% confidence interval 0.52 to 1.14) and for quadrivalent human papillomavirus vaccine versus placebo was 1.30 (95% confidence interval 0.89 to 1.91). The adjusted odds ratio for remaining wart free at 48 weeks (in those who were wart free at week 16) for imiquimod versus podophyllotoxin was 0.98 (95% confidence interval 0.54 to 1.78) and for quadrivalent human papillomavirus vaccine versus placebo was 1.39 (95% confidence interval 0.73 to 2.63). Podophyllotoxin plus quadrivalent human papillomavirus vaccine had inconclusive cost-effectiveness compared with podophyllotoxin alone.
Limitations: Hepatitis A vaccine as control was replaced by a saline placebo in a non-identical syringe, administered by someone outside the research team, for logistical reasons. Sample size was reduced from 1000 to 500 because of slow recruitment and other delays.
Conclusions: A benefit of the vaccine was not demonstrated in this trial. The odds of clearance at week 16 and remaining clear at week 48 were 46% higher with vaccine, and consistent effects were seen for both wart clearance and recurrence separately, but these differences were not statistically significant. Imiquimod and podophyllotoxin creams had similar efficacy for wart clearance, but with a wide confidence interval. The trial results do not support earlier evidence of a lower recurrence with use of imiquimod than with use of podophyllotoxin. Podophyllotoxin without quadrivalent human papillomavirus vaccine is the most cost-effective strategy at the current vaccine list price. A further larger trial is needed to definitively investigate the effect of the vaccine; studies of the immune response in vaccine recipients are needed to investigate the mechanism of action.
Trial registration: Current Controlled Trials. Current Controlled Trials ISRCTN32729817 and EudraCT 2013-002951-14.
Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 47. See the NIHR Journals Library website for further project information.
Keywords: ANOGENITAL WARTS; HUMAN PAPILLOMAVIRUS; IMIQUIMOD; PODOPHYLLOTOXIN; QUADRIVALENT HPV VACCINE; RANDOMISED CONTROLLED TRIAL.
The HIPvac [Human papillomavirus infection: a randomised controlled trial of Imiquimod cream (5%) versus Podophyllotoxin cream (0.15%), in combination with quadrivalent human papillomavirus or control vaccination in the treatment and prevention of recurrence of anogenital warts] trial compared two commonly used creams to treat genital warts: 0.15% podophyllotoxin cream (Warticon®; GlaxoSmithKlein plc, Brentford, UK) and 5% imiquimod cream (Aldara®; Meda Pharmaceuticals, Takeley, UK). It also investigated whether or not a vaccine used to prevent human papillomavirus infection, quadrivalent human papillomavirus vaccine (Gardasil®, Merck Sharp & Dohme Corp., Merck & Co., Inc., Whitehouse Station, NJ, USA), could help treat warts or prevent them from coming back in patients whose warts had been cleared. The HIPvac trial was a randomised controlled trial involving 503 patients with warts attending sexual health clinics in England and Wales. The creams and the vaccine were well tolerated; there was some soreness where the cream was applied, but no unexpected side effects. When deciding which treatment was better, we looked at whether or not the warts had cleared by 16 weeks after starting treatment and, if cleared, whether or not they returned by 48 weeks. We compared the creams against each other, and the addition of vaccine against no vaccine (a placebo injection). Patients were allowed to have cryotherapy (freezing treatment) as well, if the investigator advised this. We also calculated the value for money of each type of treatment. The two creams were very similar in how well they worked to clear the warts. One difference was that podophyllotoxin cream worked slightly quicker. The number of patients given cryotherapy was about the same for both types of cream. We had expected that recurrence of warts after treatment with imiquimod cream might be less than after treatment with podophyllotoxin cream, but, in fact, the two creams were similar. Quadrivalent human papillomavirus vaccine did not improve clearance of warts or reduce the chance of recurrence, but the result remains inconclusive. If we had been able to recuit 1000 participants as originally planned, we might have been able to be more certain about whether there was any benefit of vaccination. Further research would be needed to investigate any possible effect. The two creams offered similar value for money in treating warts. Giving patients the vaccine in addition to the cream is not good value for money at its current list price, given the uncertainty about the benefit it offers.