HIV / STI
Long-acting reversible contraceptives and the risk of sexually transmitted blood-borne infections among Canadians under 25 years of age Haylie Simmons* Haylie Simmons Nichole Austin Daniel Dutton Michelle Dimitris Sahar Saeed
Background
Sexually transmitted blood-borne infections (STBBIs) – specifically chlamydia and gonorrhea – are surging across Canada, especially among adolescent girls and young women. The use of long-acting reversible contraceptive (LARC) methods is also increasing among young women, but they do not offer any protection against STBBIs. It is therefore important to understand whether increased LARC access/uptake is associated with chlamydia/gonorrhea incidence rates among adolescent girls and young women under 25 years old.
Methods
We obtained data on monthly lab-confirmed chlamydia and gonorrhea cases among people under 25 from January 2016 to December 2021 from two provincial public health agencies. Since data on individual-level LARC use is not reliably captured in Canada, we used a policy that expanded LARC access at the population level in Ontario (known as OHIP+ in January 2018) as a proxy for LARC use. This created an opportunity to estimate the population-level impact of expanded LARC access on chlamydia/gonorrhea incidence using difference-in-differences. Ontario was selected as our treated group, and British Columbia (where no change in access occurred) as our comparator. Negative binomial models and marginal post-estimation were used to estimate the incidence rate ratio (IRR), and results will be stratified by sex.
Results
180,113 cases of chlamydia and 20,956 cases of gonorrhea were observed between January 2016 and December 2021 in Ontario and British Columbia. Preliminary results suggest the incidence rate ratio (IRR) for total gonorrhea cases for men and women under 25 was 1.24 (95% CI 1.07, 1.43), suggesting that expanded LARC access may be associated with increased gonorrhea rates at the population level (an absolute increase of 31 cases post-policy). The IRR for total chlamydia cases for people under 25 was 1.06 (0.92, 1.22), translating to an absolute increase of 67 cases attributable to expanded LARC access. Sex-stratified analyses are currently underway.
Conclusion
Given contemporaneous increases in LARC access/use and STBBI incidence among people under 25, it is essential to understand if the two are linked. We found that expanded LARC access may be associated with increases in gonorrhea incidence among people under 25.