(P338) Automated reminders improve the return rate of STI self-collection test kits among users of the I Want The Kit online service

Background: Bacterial sexually transmitted infections (STIs) are at an all-time high in the United States (US). Online-ordered self-collection kits with laboratory testing services for STIs could dramatically expand access to testing. IWantTheKit (IWTK) is an online platform offering free STI self-collection mail-in kits to clients in four states. Because approximately one third of IWTK orders are never returned by users for testing, there is an opportunity for IWTK to improve kit return rates and link more people to STI care. IWTK implemented an email- or SMS-based reminder system for unreturned kits in November 2021. Notifications were sent to users 91 days after kits were mailed out if they were not returned. We estimated the effect of these reminders on the time to kit return among IWTK users from 2021 to 2022.

Methods: Deidentified, routinely-collected, self-reported demographic, sexual behavior, and residence data were collected from IWTK orders from 2021 to 2022. Time to kit return was the outcome of interest. The predictor of interest was the reminder delivery. Cox proportional hazards regression models were used to estimate hazards ratios (HRs) and 95% confidence intervals (CIs), adjusting for time-invariant and time-variant covariates.

Results: IWTK distributed 11,730 test kits from February 3, 2021, until December 15, 2022, with an overall return rate of 62%. Throat swabs (8,111, 69.1%) and vagina swabs (6,867, 58.5%) were the most ordered. 3,699 orders (31.5%) were from repeat IWTK users. Mean user age was 30 years; 6,577 orders (56.1%) were from self-identified women, who were slightly more likely than men or genderqueer/non-binary/transgender users to return kits. 5,372 (45.8%) orders were from Black users, and 3,900 (33.2%) were from white users. Compared to orders in the pre-reminder period, orders receiving reminders had an estimated 149% increased hazard of kit return (HR: 2.50, 95% CI: 1.88, 3.32, p< 0.001).

Conclusion: Automated reminders were successful during this study period and may be a cost-effective strategy to substantially increase the rate of IWTK test return. The timing and frequency of reminders requires further study to maximize kit return and linkage to STI treatment.