Time trade-off procedure for measuring health utilities loss with human papillomavirus–induced diseases: a multicenter, retrospective, observational pilot study in Italy

Background. The economic evaluation of any human papillomavirus (HPV) vaccination strategy requires the measurement of clinical benefits (quality-adjusted life-years [QALY]) gained to reflect both the increase in life expectancy and the economic benefits associated with an effective intervention. Objective. The purpose of this pilot study was to investigate the feasibility of a standardized time trade-off (TTO) procedure to quantify utilities loss in health states affected by HPV-induced pathologies in Italy. Methods. This multicenter, retrospective, observational, cross-sectional study was designed to elicit data on utilities in a cohort of women with a histologically confirmed diagnosis of high-grade cervical intraepithelial neoplasias (CIN2-3). An algorithm for the computerized administration of a TTO questionnaire was developed for the standardized elicitation of data on health utilities in CIN2-3, anogenital warts, and invasive cervical cancer. The European Quality of Life–5 Dimensions (EQ-5D) questionnaire was used to assess the respondents' baseline perception of their health conditions. The correlation between utilities and age, time from conization to questionnaire administration, and EQ-5D score, was tested using the Spearman rank correlation coefficient (ρ) as a measure of validity. Results. Of 42 enrolled patients, 36 responded (85.7%) (mean [SD] age, 37.2 [9.0] years). The women's perception of their health state was high (mean [SD] EQ-5D score, 0.93 [0.10]). The mean utility values were 0.73 (0.22), 0.71 (0.35), and 0.02 (0.08) for CIN2-3, anogenital warts, and invasive cervical cancer, respectively. Based on ρ values, none of the 3 HPV-induced pathologies considered was significantly correlated with utility. Nonsignificant variability was found among utilities elicited for anogenital warts (range, 0.54 [0.47] to 0.79 [0.27]); this variability was a limitation of this pilot study and was likely the result of the limited sample size. Conclusions. Based on the findings from this pilot study, a TTO standardized procedure is expected to be feasible and appropriate for assessing utilities in patients affected by HPV-related diseases and for cost-effectiveness analyses of cervical cancer prevention in Italy.