Syphilis Mortality on the Decline in the United States, 2000-2010

introduction:  After reaching an all-time low in 2000, the incidence of syphilis has steadily increased in recent years. Despite the resulting growth of interest in this infectious bacterial disease, there remains a paucity of data about the mortality burden of syphilis and changes in trends during this time period.  In an effort to reduce the gap in knowledge the present analyses examined all syphilis-related deaths from 2000-2010 using national multiple-cause-of-death (MCD) data. 

 methods: Using ICD-10 classification, all syphilis-related deaths were identified using the MCD dataset for the period 2000-2010. Descriptive statistics and age-adjusted mortality rates were calculated to examine trends of disease burden by age, sex, race/ethnicity, and geographic region.  Poisson regression was used to analyze mortality trends over time. Planned analyses include a matched case-control to describe associations between syphilis and other comorbid conditions contributing to death.

results: Over the 11 year period, a total of 1,345 deaths were attributed to syphilis; 31% identified syphilis as the underlying cause of death.  A majority of decedents were male (58%) and were primarily white or black (88%; n=1,188). Older adults had the highest mortality rates: 65-74 years (0.11; 95%CI = 0.09-0.12), 75-85 years (0.25; 95%CI = 0.22-0.27), and 85+ years (0.49; 95%CI=0.43-0.55). Blacks were disproportionally affected compared to whites (age-adjusted rate ratio = 11.9; 95%CI =10.9-12.9). Though the sample size is not large, there were 23 cases of neonatal syphilis. Age-adjusted time trends indicated a 4.25% annual decline in mortality for this period.

discussion: Despite the increasing incidence of disease, overall death attributed to syphilis appears to be declining. However, among elderly adults, this infection continues to be an important cause of death. Understanding the mortality patterns and related comorbid conditions can help aide clinical efforts to more quickly identify high-risk patients with syphilis and provide appropriate, potentially life-saving, treatment.