Estimation of the Lifetime Quality-Adjusted Life Years (QALYs) Lost Due to Syphilis acquired in the United States in 2018

Background The purpose of this study was to estimate the health impact of syphilis in the United States in terms of the number of quality-adjusted life years (QALYs) lost attributable to infections in 2018. Methods We developed a Markov model which simulates the natural history and long-term sequelae of syphilis. The model was parameterized by sex (men and women), sexual orientation (women who have sex with men, men who have sex with women [MSW], and men who have sex with men [MSM]), and by age at primary infection. We developed a separate decision tree model to account for health losses due to congenital syphilis. We estimated the average lifetime number of QALYs lost per infection, and the total expected lifetime number of QALYs lost due to syphilis acquired in 2018. We performed probabilistic sensitivity analysis to account for uncertainty in the model’s estimates. Findings We estimated the average number of discounted lifetime QALYs lost per infection as 0.09 [0.03-0.19 95% uncertainty interval (UI)]. The QALY loss per infection was lower among MSM (0.06) than among MSW (0.15) and women (0.10). The total expected number of QALYs lost due to syphilis acquired in 2018 was 13,349 (5,071-31,360 95%UI). MSM account for 6,373 (47.7%) of the overall burden, compared to MSW (32.1%) and women (20.2%). For each case of congenital syphilis, we estimated 1.79 (1.43-2.16 95%UI) QALYs lost for the child and 0.06 (0.01-0.14 95%UI) QALYs lost for the mother. These per-case estimates correspond to 2,332 (1,871-2,825 95%UI) and 79 (17-177 95%UI) QALYs lost for children and mothers, respectively, due to congenital syphilis in 2018. Conclusion Syphilis causes substantial health losses in adults and children. Quantifying these health losses in terms of QALYs can inform cost-effectiveness analyses and can facilitate comparisons of the burden of syphilis to that of other diseases.