The Estimated Lifetime Medical Cost of Syphilis in the United States

An Interactive Modeling Tool for Projecting the Health and Direct Medical Cost Impact of Changes in the Sexually Transmitted Diseases Prevention Program Budgets

CONTEXT

Estimating the return on investment for public health services, tailored to the state level, is critical for demonstrating their value and making resource allocation decisions. However, many health departments have limited staff capacity and expertise to conduct economic analyses in-house.

PROGRAM

We developed a user-friendly, interactive Excel-based spreadsheet model that health departments can use to estimate the impact of increases or decreases in sexually transmitted infection (STI) prevention funding on the incidence and direct medical costs of chlamydia, gonorrhea, syphilis, and STI-attributable HIV infections. Users tailor results to their jurisdictions by entering the size of their population served; the number of annual STI diagnoses; their prior annual funding amount; and their anticipated new funding amount. The interface was developed using human-centered design principles, including focus groups with 15 model users to collect feedback on an earlier model version and a usability study on the prototype with 6 model users to finalize the interface.

IMPLEMENTATION

The STI Prevention Allocation Consequences Estimator ("SPACE Monkey 2.0") model will be publicly available as a free downloadable tool.

EVALUATION

In the usability testing of the prototype, participants provided overall positive feedback. They appreciated the clear interpretations, outcomes expressed as direct medical costs, functionalities to interact with the output and copy charts into external applications, visualization designs, and accessible information about the model's assumptions and limitations. Participants provided positive responses to a 10-item usability evaluation survey regarding their experiences with the prototype.

DISCUSSION

Modeling tools that synthesize literature-based estimates and are developed with human-centered design principles have the potential to make evidence-based estimates of budget changes widely accessible to health departments.

Access to Benzathine Penicillin G Treatment for Persons With Syphilis, Maricopa County, Arizona, 2021

BACKGROUND

As the incidence of syphilis continues to increase, examining benzathine penicillin G (BPG) treatment data provides valuable insight for public health strategies. This study analyzed the trends of where BPG is administered relative to the initial clinical site of syphilis diagnosis. Our findings are timely in the context of recent national BPG shortages.

METHODS

The analysis included persons diagnosed with any syphilis stage in Maricopa County, Arizona, from January 1, 2021, to December 31, 2021. The Arizona surveillance database (PRISM) was the source of demographic, testing, and treatment data.

RESULTS

Of a total of 4028 persons with syphilis, 3038 (75.4%) received at least 1 injection of BPG. Among persons who received an initial BPG injection, only 1719 (56.6%) were diagnosed and treated at the same clinical site type. The Maricopa County Sexually Transmitted Disease Clinic administered BPG to 48.8% (n = 1483) of persons with syphilis who received an initial injection.

CONCLUSIONS

Our findings analyze trends in BPG administration that are likely due to treatment referral practices and medication cost. Administration of BPG is not guaranteed at the clinical site of diagnosis, highlighting concerns regarding access to BPG. A burden is placed on patients who are required to leave their diagnosing provider to seek syphilis treatment at other health facilities that administer BPG.

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 that simulates the natural history and management of syphilis. The model was parameterized by sex and 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 quantify 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.

RESULTS

We estimated the average number of discounted lifetime QALYs lost per infection as 0.09 (95% uncertainty interval [UI] .03-.19). The total expected number of QALYs lost due to syphilis acquired in 2018 was 13 349 (5071-31 360). Although per-case loss was the lowest among MSM (0.06), MSM accounted for 47.7% of the overall burden. For each case of congenital syphilis, we estimated 1.79 (1.43-2.16) and 0.06 (.01-.14) QALYs lost in the child and the mother, respectively. We projected 2332 (1871-28 250) and 79 (17-177) QALYs lost for children and mothers, respectively, due to congenital syphilis in 2018.

CONCLUSIONS

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.

Variation in Patterns of Racial and Ethnic Disparities in Primary and Secondary Syphilis Diagnosis Rates Among Heterosexually Active Women by Region and Age Group in the United States

BACKGROUND

Syphilis rates have increased substantially over the past decade. Women are an important population because of negative sequalae and adverse maternal outcomes including congenital syphilis. We assessed whether racial and ethnic disparities in primary and secondary (P&S) syphilis among heterosexually active women differ by region and age group.

METHODS

We synthesized 4 national surveys to estimate numbers of heterosexually active women in the United States from 2014 to 2018 by region, race and ethnicity, and age group (18-24, 25-29, 30-44, and ≥45 years). We calculated annual P&S syphilis diagnosis rates, assessing disparities with rate differences and rate ratios comparing White, Hispanic, and Black heterosexually active women.

RESULTS

Nationally, annual rates were 6.42 and 2.20 times as high among Black and Hispanic than among White heterosexually active women (10.99, 3.77, and 1.71 per 100,000, respectively). Younger women experienced a disproportionate burden of P&S syphilis and the highest disparities. Regionally, the Northeast had the highest Black-White and Hispanic-White disparities using a relative disparity measure (relative rate), and the West had the highest disparities using an absolute disparity measure (rate difference).

CONCLUSIONS

To meet the racial and ethnic disparity goals of the Sexually Transmitted Infections National Strategic Plan, tailored local interventions that address the social and structural factors associated with disparities are needed for different age groups.

The Estimated Direct Lifetime Medical Costs of Sexually Transmitted Infections Acquired in the United States in 2018

BACKGROUND

We estimated the lifetime medical costs attributable to sexually transmitted infections (STIs) acquired in 2018, including sexually acquired human immunodeficiency virus (HIV).

METHODS

We estimated the lifetime medical costs of infections acquired in 2018 in the United States for 8 STIs: chlamydia, gonorrhea, trichomoniasis, syphilis, genital herpes, human papillomavirus (HPV), hepatitis B, and HIV. We limited our analysis to lifetime medical costs incurred for treatment of STIs and for treatment of related sequelae; we did not include other costs, such as STI prevention. For each STI, except HPV, we calculated the lifetime medical cost by multiplying the estimated number of incident infections in 2018 by the estimated lifetime cost per infection. For HPV, we calculated the lifetime cost based on the projected lifetime incidence of health outcomes attributed to HPV infections acquired in 2018. Future costs were discounted at 3% annually.

RESULTS

Incident STIs in 2018 imposed an estimated $15.9 billion (25th-75th percentile: $14.9-16.9 billion) in discounted, lifetime direct medical costs (2019 US dollars). Most of this cost was due to sexually acquired HIV ($13.7 billion) and HPV ($0.8 billion). STIs in women accounted for about one fourth of the cost of incident STIs when including HIV, but about three fourths when excluding HIV. STIs among 15- to 24-year-olds accounted for $4.2 billion (26%) of the cost of incident STIs.

CONCLUSIONS

Incident STIs continue to impose a considerable lifetime medical cost burden in the United States. These results can inform health economic analyses to promote the use of cost-effective STI prevention interventions to reduce this burden.