The association between area- and individual-level risk factors and chlamydia infection a sexual health clinic
Background: Chlamydia is the most common sexually transmitted infection (STI) in Canada. Although the literature has focused on individual-level risk factors as the greatest determinants for chlamydia infection, more recent research has investigated the role of neighbourhood socioeconomic status (SES) on risk for chlamydia infection. The present study aims to investigate the relationship between multiple area- and individual-level risk factors and chlamydia infection in a sexual health clinic. Methods: Individuals who were tested for chlamydia at the Kingston, Frontenac and Lennox & Addington (KFL&A) Public Health sexual health clinic from April 2016 to March 2017 were included in this study. The four indices of the Ontario Marginalization (ON-Marg) Index; namely, material deprivation, dependency, residential instability and ethnic concentration, were used as measures of neighbourhood SES. Individual-level risk factors included variables that were captured from the questionnaire administered at the time of examination. Logistic regression was used to compute odds ratios (OR) for all risk factor variables. Outcome data was plotted on a geographic information system (GIS) to compare marginalization differences based on chlamydia test result. Results: A total of 1775 individuals were tested for chlamydia at the Clinic, with 208 (11.7%) testing positive on their first Clinic visit. Age (OR=4.84, 95% CI 2.18-10.74; <20 versus >40 years), number of sexual partners in the previous 2 months (OR=3.11, 95% CI 1.06-9.10; 2 partner versus no partners), condom use (OR=2.09, 95% CI 1.07-4.09; rarely versus always using condoms), and STI contact (OR=6.16, 95% CI 4.35-8.74) were significant individual-level predictors for infection. Apart from ethnic concentration of the ON-Marg Index, there was a trend suggesting an association between the highest levels of marginalization and increased odds of chlamydia infection compared to the lowest levels of marginalization. However, this association was only statistically significant for the dependency index (OR=1.90, 95% CI: 1.05-3.43; most deprived versus least deprived). Conclusions: Populations living in highly marginalized neighbourhoods, an established marker of low SES, were found to be at a significantly higher odds for chlamydia infection for one of the four ON-Marg indices; namely, dependency. More research is warranted to further clarify the role of neighbourhood SES on the risk of chlamydia infection.