Testing trajectories for GetCheckedOnline in British Columbia: Implications for equity, stewardship and sustainability of digital STI testing services

Background Digital services for sexually transmitted and blood borne infection (STBBI) testing may influence demand in publicly funded health systems by enabling low barrier, self-directed access to testing, raising concerns about repeated use and sustainability. We examined longitudinal utilization of GetCheckedOnline, British Columbias digital STBBI testing service, to characterize testing trajectories and assess factors associated with higher intensity use. Methods We conducted a retrospective cohort study using GetCheckedOnline program data for users who created an account between April 2020 and November 2022, with 24 months of follow-up. We used group-based trajectory modelling to identify patterns of testing over time among (1) all users and (2) users with at least one test. Multilevel regression models with local health area random intercepts were used to examine associations between higher intensity trajectory membership, individual risk indicators, and geographic clustering. Results Among 34,228 users, 22,542 (65.9%) completed at least one test and 42,451 tests were conducted (median 1; range 0-44). Two trajectories were identified in both analytic samples, with a minority demonstrating sustained higher intensity testing. The top 10% of users accounted for 39.6% of tests. Higher intensity trajectory membership was associated with sexual risk indicators including having multiple partners, condomless sex with multiple partners, and prior STBBI diagnosis. Geographic clustering across local health areas was modest in the null model (ICC 0.042) and attenuated with adjustment. Conclusion GetCheckedOnline utilization reflects a prevention-oriented pattern that appears more consistent with service needs than indiscriminate overuse. A small subset of users with elevated sexual risk account for higher-intensity testing. Findings support risk aligned stewardship including education and differentiated guidance, rather than universal restrictions to reducing testing volumes.