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 (p) 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-SD 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 p 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.