High Chlamydia Incidence Rates Associated with Increased Cervical Cancer Mortality Rates in US Counties: The Potential Role of HPV Infection and Implications for Cancer Prevention

Background: The association between the prevalence of human papillomavirus (HPV) infection and the cervical cancer mortality rate has not been well studied due to the lack of HPV surveillance data.  The incidence rate of Chlamydia trachomatis infection may be used as a surrogate measure for disease burden of HPV infection because of similar transmission patterns, high correlation between two diseases, and good quality of surveillance data.   

Objectives: To assess the association between the chlamydia incidence rate among women and the cervical cancer mortality rate across U.S. counties.

Methods: The county-level female chlamydia cases in 2000 were obtained from 48 state health departments.  Cervical cancer mortality data in 2000-2004 were exacted from the Surveillance, Epidemiology, and End Results (SEER)*Stat.  The relationship between the chlamydia rate and the cervical cancer mortality rate was initially examined by the correlation and the quintile plot.  Due to the non-linear association, counties were dichotomized as “high chlamydia rate” if the rates were greater than the US rate in 2000 (404/100,000 women).  A multivariate negative binomial model was used to assess the association between the chlamydia rate and the cervical cancer mortality rate, adjusting for socio-demographic variables, behavioral risk factors, and physician and hospital availability. 

Results: During 2000-2004, a total of 19,898 cervical cancer deaths occurred in women>= 20 years among 3,105 U.S. counties. Counties with high chlamydia rates had significantly increased cervical cancer mortality rates (rate ratio=1.10, p-value=0.0002), after controlling for the proportions of black and Hispanic populations, socioeconomic status, Papanicolaou test rate, health care coverage, and doctor and hospital availability. 

Conclusions: High chlamydia rates were independently associated with increased cervical cancer mortality rates, and the association was possibly due to the effect of HPV infection. 

Implications for Programs, Policy, and/or Research: Collaboration between cancer researchers and local STD control programs should be considered to deliver health services to high-risk populations.