Examining the Impact of Federally-funded Syphilis Elimination Activities

Background:
CDC has funded syphilis elimination activities since 1998.

Objective:
To examine whether the amount of federal funding allocated for syphilis elimination activities is associated with state-level changes in annual syphilis incidence rates.

Method:
We employed regression analyses of syphilis rates (primary, secondary, and early latent syphilis) and syphilis elimination funding at the state level. We include observations from 28 states (those that were initially targeted for syphilis elimination in 1998 or 1999) for each year from 1997 to 2005. Funding allocations to cities were counted as part of the allocation to their respective states. The dependent variables were the syphilis incidence rate (in log form) and the annual percentage change in the syphilis incidence rate. The independent variable of interest was FUNDING, the average allocation of syphilis elimination funding (per capita) in a given state in the given year and in the two previous years. The models included state dummy variables to capture fixed, unobserved state-specific factors that influence syphilis incidence and year dummy variables to capture time-varying factors common to all states. Other explanatory variables included the robbery rate, the poverty rate, percent black, and percent aged 15 to 24 years.

Result:
In both models, the coefficient of the funding variable was negative and significant, indicating that greater amounts of funding in a given year are associated with reductions in syphilis rates in subsequent years. The results were generally robust to changes in the model specifications and estimation procedures.

Conclusion:
The correlation between syphilis funding and syphilis incidence is consistent with- but does not establish- a causal association between syphilis elimination activities and decreased syphilis incidence rates.

Implications:
The recent increases in early syphilis rates in the United States might have been much more pronounced had there been no syphilis elimination activities.