Risk of genital warts in renal transplant recipients-A registry-based, prospective cohort study

Genital warts (GWs) are a risk factor for subsequent human papillomavirus (HPV)-related anogenital cancers. In this register-based, prospective cohort study, we estimated the risk of GWs in renal transplant recipients (RTRs) compared with a nontransplanted cohort. In a nationwide database, we identified first-time RTRs in Denmark during 1996 to 2015. For each RTR, 50 age- and sex-matched nontransplanted individuals were selected from the population registry. Information on GWs, sociodemographic characteristics, HPV vaccination, and other causes of immunosuppression was retrieved from registries. We estimated the cumulative incidence of GWs and used Cox regression to estimate hazard ratios (HR) of GWs in RTRs vs non-RTRs. We included 3268 RTRs and 162 910 non-RTRs without GWs 1 year before baseline. RTRs had higher hazard of GWs than non-RTRs (HR = 3.30; 95% confidence interval, 2.76-3.93, adjusted for sex, age, education, and income). The increased hazard of GWs compared with non-RTRs was more pronounced in female than in male RTRs. Although not statistically significant, the hazard tended to be higher in RTRs with functioning grafts compared with RTRs on dialysis after graft failure. The hazard of GWs was increased <1 year after transplantation and remained increased during >= 10 years. In conclusion, RTRs had substantially higher risk of GWs than non-RTRs.