Background: The objective was to determine trends in age disparities between reported rates of chlamydia, gonorrhea, and infectious syphilis among younger versus middle-age Canadians.
Methods: We examined age- and sex-specific reported rates of chlamydia, gonorrhea, and infectious syphilis between 1997 and 2007. Sexually transmitted infection (STI) rates in the younger age group (15–29 years) were compared to the middle-age group (40–59 years) over the 11-year period. We used Poisson regression to examine trends in age-specific (younger:middle-age) rate ratios.
Results: Between 1997 and 2007, both the number and rate of reported cases increased for all 3 nationally notifiable STIs. Although chlamydia and gonorrhea rates continued to be higher among younger adults, rates of all 3 STIs increased more dramatically among middle-age adults. Between 1997 and 2007, chlamydia rates increased by 86.8% among adults aged 15 to 29 (P <0.0001) and 165.9% among adults 40- to 59-years-old (P <0.0001). The corresponding increases for gonorrhea were 133.3% (P <0.0001) and 210.2% (P <0.0001) respectively. Infectious syphilis rates increased 5-fold among younger adults compared to an increase of 11-fold among middle-age adults (P <0.0001) since 1997. The reported rate ratios (younger:middle-age) decreased over time for chlamydia (P <0.0001), gonorrhea (P <0.0001), and syphilis (P = 0.005). Males were disproportionately represented among reported chlamydia, gonorrhea, and infectious syphilis cases, constituting 59.8%, 87.6%, and 93.0% of middle-age adult cases, respectively, in 2007.
Conclusions: Middle-age adults may be increasingly affected by chlamydia, gonorrhea and infectious syphilis. There is a need for sexual health information targeting Canada's middle-age adults and their health care providers.
Although younger adults represent a greater number of chlamydia, gonorrhea, and infectious syphilis cases, reported rates of all 3 sexually transmitted infections among middle-age adults have increased more dramatically over time.
Public Health Agency of Canada, Ottawa, Canada.
The authors thank Maureen Perrin and Robert Lerch for their constructive comments on the manuscript, Dena Schanzer for her statistical assistance, and the provinces and territories for their continued efforts in ensuring the success of surveillance of STIs in Canada.
Correspondence: Lily Fang, MHSc, Public Health Agency of Canada, 100 Eglantine Driveway, Ottawa, Ontario, K1A 0K9, Canada. E-mail: Lily_Fang@phac-aspc.gc.ca.
Received for publication March 9, 2009, and accepted June 26, 2009.