National Incidence of Syphilitic Uveitis Grew in the US Over a 10-Year Period

Tahreen A. Mir, MD

Credit: Vanderbilt University Medical Center

A cross-sectional study revealed a rising national incidence of syphilitic uveitis-related hospitalizations from 2010 to 2019 in the United States, which mirrored a similar rise in syphilis cases.¹

Across an analysis of approximately 445,000 patients, a team of investigators from Vanderbilt University Medical Center found the national incidence of syphilitic uveitis in the US was 0.15 per 100,000 population, with a notable increase across all four geographic regions, in men, and those facing socioeconomic disparities.

“This cross-sectional study reported an increasing nationwide incidence of syphilitic uveitis cases, emphasizing the need for ophthalmologists to maintain a high index of suspicion for syphilitic uveitis when evaluating patients with intraocular inflammation,” wrote the investigative team, led by Tahreen A. Mir, MD, of the department of ophthalmology at Vanderbilt University Medical Center.

Although rare, the most common ocular manifestation of syphilis is syphilitic uveitis, which can result in irreversible vision loss. According to data from the Centers for Disease Control and Prevention (CDC), the incidence of syphilis has increased in the US every year since 2001, with a 74% increase since 2017.² A survey from the International Ocular Syphilis Study Group showed that 53.2% of uveitis specialists reported an increase in the amount of syphilitic uveitis cases managed over the past decade.

Despite these increases, however, there remains a national shortage of long-acting injectable penicillin G benzathine, the standard of care for syphilitic uveitis.¹ Mir and colleagues set out to assess the national and regional incidence of syphilitic uveitis-related hospitalizations in the US and any related sociodemographic characteristics. The retrospective, cross-sectional study utilized the Nationwide Inpatient Sample to identify all inpatient admissions with a diagnosis of syphilitic uveitis in the US between 2010 and 2019.

Investigators performed analyses to assess baseline sociodemographic characteristics, as well as to identify national and regional trends in syphilitic uveitis incidence. All hospital admissions with a diagnosis of syphilis, uveitis, and/or syphilis were eligible for study inclusion. Statistical analysis occurred in June 2023.

For the analysis, the main outcome was trend determination in the national and regional incidence of syphilitic uveitis–related hospitalizations across the US. Secondary outcomes consisted of the sociodemographic characteristics of patients with syphilitic uveitis, incidence rates stratified by sex, race, and ethnicity, and the median charge per syphilitic uveitis hospitalization.

A total of 444,674 patients identified in the Nationwide Inpatient Sample were included in the analysis. Patients had a median age of 53 years and approximately 55% were male. During the 10-year study period, an estimated 5581 syphilitic uveitis-related hospitalizations were identified and included in the study.

The median age of people with syphilitic uveitis was 45 years, with disproportionate effects on younger individuals in the fourth (22.0%) and fifth (26.4%) decade of life. A total of 4395 affected patients (78.9%) were men.

Upon analysis, the national incidence of syphilitic uveitis-related hospital admissions was 0.15 per 100,000 population during the study period, with lowest incidence in 2011 (0.08 per 100,000 population) and the highest incidence in 2019 (0.23 per 100,000 population; P = .04). Regional analyses revealed an increasing number of syphilitic uveitis admissions across all 4 geographic regions, with the highest incidence in the South and West (0.17 per 100,000 population each).

Moreover, the average incidence of syphilitic uveitis was 4 times higher in men (0.25 per 100,000 population), than in women (0.06 per 100,000 population), but both had an increasing trend of syphilitic uveitis hospitalizations during the study period. A total of 1293 patients (23.2%) with syphilitic uveitis had comorbid AIDS, with an annual incidence of 0.04 per 100,000 population.

In terms of racial and socioeconomic disparities related to the incidence of syphilitic uveitis hospitalizations, syphilitic uveitis disproportionately affected African American individuals (1787 patients [32%], despite only composing 13.6% of the population. Syphilitic uveitis disproportionately affected patients in the lowest median household income quartile (2163 [38.3%], while the lowest incidence was in the highest median household income quartile.

Given its rare status, syphilitic uveitis may present a diagnostic challenge for eye care professionals. Mir and colleagues noted survey data from the International Ocular Syphilis Study Group revealed initial misdiagnosis is one of the most common (64%) causes of a poor visual outcome among this population.

“Given the concomitant national shortage of injectable penicillin G, results suggest that clinicians should maintain a high index of suspicion for syphilis when evaluating patients with intraocular inflammation,” investigators wrote.

References

1. _{Mir TA, Kim SJ, Fang W, Harvey J, Hinkle DM. Rising Incidence of Syphilitic Uveitis–Related Hospitalizations in the US. JAMA Ophthalmol. Published online November 22, 2023. doi:10.1001/jamaophthalmol.2023.5386}
2. _{Centers for Disease Control and Prevention. Sexually transmitted disease surveillance 2020. Accessed December 21, 2023. https://www.cdc.gov/std/statistics/2020/2020-SR-4-10-2023.pdf}