Imiquimod versus podophyllotoxin, with and without human papillomavirus vaccine, for anogenital warts: the HIPvac factorial RCT.

BACKGROUND

The comparative efficacy, and cost-effectiveness, of imiquimod or podophyllotoxin cream, either alone or in combination with the quadrivalent HPV vaccine (Gardasil

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

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

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

Déclaration de conflit d'intérêts

Richard Gilson reports grants from the National Institute for Health Research (NIHR) during the conduct of the study. Lewis J Haddow reports grants from the NIHR Health Technology Assessment programme during the conduct of the study, grants from the British HIV Association‘s Scientific and Research Committee and personal fees from Gilead Sciences, Inc. (London, UK) outside the submitted work.