Differential declines in syphilis-related mortality in the United States, 2000-2014

After reaching an all time low in 2000, the rate of syphilis in the United States has been steadily increasing. Parallel benchmarking of the disease's mortality burden has not been undertaken.

Using ICD-10 classification, all syphilis-related deaths in the national Multiple Cause of Death dataset were examined for the period 2000-2014. Descriptive statistics and age-adjusted mortality rates were generated. Poisson regression was performed to analyze trends over time. A matched case-control analysis was conducted to assess the associations between syphilis-related deaths and comorbid conditions listed in the death records.

A total of 1,829 deaths were attributed to syphilis; 32% (n = 593) identified syphilis as the underlying cause of death. Most decedents were men (60%) and either black (48%) or white (39%). Decedents aged ≥85 years had the highest average mortality rate (0.47 per 100,000 population; 95% confidence interval [CI], 0.42-0.52). For the sampled period, the average annual decline in mortality was -2.90% (95% CI, -3.93% to -1.87%). However, the average annual percent change varied across subgroups of interest.

Declines in U.S. syphilis mortality suggest early detection and improved treatment access likely helped attenuate disease progression; however, increases in the disease rate since 2000 may be offsetting the impact of these advancements.