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

This study of British Columbia's GetCheckedOnline service reveals that while a small subset of high-risk users accounts for the majority of tests, overall utilization aligns with prevention needs rather than indiscriminate overuse, supporting a stewardship approach focused on risk-based education rather than universal restrictions.

The Gist

Imagine a public health system as a giant, well-stocked library. For years, people have had to walk in, wait in line, and talk to a librarian to check out a specific book (get tested for sexually transmitted infections). But recently, the library launched a digital kiosk called GetCheckedOnline. This kiosk lets people check out books from the comfort of their own homes, anytime they want, with no lines and no awkward conversations.

The library managers (health officials) were a little worried. They thought: "If we make it this easy, won't people just keep checking out books they don't need? Will the shelves run empty? Will this service become too expensive to keep running?"

This study is like a traffic camera that watched who used the kiosk over two years to see what was actually happening.

What They Found: The "Heavy Readers" vs. The "Casual Browsers"

The researchers looked at data from over 34,000 people who signed up. Here is the breakdown:

1. Most people are just checking in: About two-thirds of the users actually took a test. Most of them only did it once or twice. Think of these people as casual browsers who stop by the kiosk when they feel a little unsure or just want peace of mind.
2. A small group is the "Heavy Readers": There was a tiny group (the top 10%) who used the kiosk a lot. In fact, this small group was responsible for nearly 40% of all the tests done.
   • The Analogy: Imagine a coffee shop. Most customers buy one cup of coffee a week. But there's a small group of regulars who come in five times a day. The study found that these "heavy coffee drinkers" weren't just drinking randomly; they were the ones who actually needed the caffeine the most.

Why Were They Using It So Much?

The study asked: Are these heavy users wasting resources, or do they have a real need?

The answer was clear: They have a real need. The people who used the service the most were the ones with higher health risks—people who had multiple partners, didn't always use protection, or had been infected before.

It's like a fire alarm system. If a building has a fire alarm that goes off constantly, you might think the system is broken or being abused. But if you look closely, you see that the alarms are only going off in the rooms where there is actual smoke and fire. The "heavy users" of this digital test were the rooms with the smoke. They weren't overusing the service; they were using it exactly as intended to stay safe.

The "Neighborhood" Factor

The researchers also looked at whether certain neighborhoods used the service more than others. They found that while some areas had slightly more users, the difference wasn't huge. It wasn't like one town was "addicted" to the kiosk while another ignored it. The usage was fairly spread out, just like how rain falls on a field—it's a little wetter in some spots, but the whole field gets watered.

The Big Takeaway: Don't Lock the Doors

So, what does this mean for the future of the service?

Some might argue, "Since a few people use it so much, let's put a limit on how many times anyone can test, or make it harder to access, to save money."

The study says: No, don't do that.

If you put a lock on the door or limit the number of tests, you aren't stopping the "abusers" (because there aren't really any); you are just locking out the people who are at the highest risk of getting sick.

The Solution: Instead of building a wall, we should build a guidepost.

• For the casual users: A simple reminder that testing is good, but maybe they don't need to do it every week.
• For the "heavy users" (the high-risk group): More support, better education, and a clear path to get help.

In short: The digital testing service is working exactly as it should. It's a tool that is being used by the people who need it most. Rather than trying to restrict access to save money, health officials should focus on stewardship—which means guiding the right people to the right help, ensuring the service stays open and sustainable for everyone who needs it.

Technical Summary

1. Problem Statement

The study addresses a critical tension in public health: the potential of digital services for Sexually Transmitted and Blood-Borne Infection (STBBI) testing to improve access versus concerns regarding their sustainability.

• The Concern: Low-barrier, self-directed digital testing platforms (like GetCheckedOnline) may inadvertently encourage "indiscriminate overuse" or repeated testing by users without clinical need. This raises fears of straining publicly funded health systems and diverting resources from high-need populations.
• The Knowledge Gap: There was a lack of longitudinal data characterizing how users actually engage with these services over time. Specifically, it was unclear whether high-volume usage was driven by a small subset of high-risk individuals or represented a widespread pattern of unnecessary utilization.

2. Methodology

The researchers conducted a retrospective cohort study utilizing administrative data from the GetCheckedOnline program in British Columbia, Canada.

• Study Population: Users who created an account between April 2020 and November 2022.
• Follow-up Period: 24 months of longitudinal observation.
• Sample Size: 34,228 total users.
• Analytical Approach:
  1. Group-Based Trajectory Modelling (GBTM): Used to identify distinct patterns of testing behavior over time. This was applied to two groups: (a) all registered users and (b) users who completed at least one test.
  2. Multilevel Regression Models: Employed to examine associations between membership in "higher intensity" testing trajectories and specific variables.
     • Fixed Effects: Individual risk indicators (e.g., number of partners, condom use, prior STBBI history).
     • Random Effects: Local Health Area (LHA) random intercepts were included to account for geographic clustering.
• Key Metrics: Testing frequency, trajectory membership, and the Intraclass Correlation Coefficient (ICC) to measure geographic variation.

3. Key Contributions

• Trajectory Characterization: The study moves beyond aggregate testing numbers to map the temporal dynamics of digital testing, distinguishing between sporadic users and those with sustained high-frequency engagement.
• Risk-Stratified Analysis: It links behavioral trajectories directly to clinical risk factors, providing evidence that high-intensity use is not random but correlated with specific sexual health risks.
• Stewardship Framework: The paper proposes a shift in policy from "universal restrictions" (which may hinder access for low-risk users) to "risk-aligned stewardship," where guidance and education are tailored based on user risk profiles.

4. Key Results

• Utilization Volume:
  • 65.9% (22,542) of registered users completed at least one test.
  • Total tests conducted: 42,451.
  • Median tests per user: 1 (Range: 0–44).
• Trajectory Patterns:
  • GBTM identified two distinct trajectories in both analytic samples:
    1. A majority group with low or sporadic testing.
    2. A minority group demonstrating sustained higher-intensity testing.
  • Pareto Distribution: The top 10% of users accounted for 39.6% of all tests conducted.
• Predictors of High-Intensity Use:
  • Membership in the higher-intensity trajectory was significantly associated with established sexual risk indicators:
    • Having multiple sexual partners.
    • Engaging in condomless sex with multiple partners.
    • History of prior STBBI diagnosis.
• Geographic Clustering:
  • Geographic variation in testing intensity was modest (ICC = 0.042 in the null model).
  • This clustering was further attenuated (reduced) after adjusting for individual risk factors, suggesting that individual behavior drives testing volume more than geographic location.

5. Significance and Implications

• Validation of Service Model: The findings suggest that GetCheckedOnline utilization reflects a prevention-oriented pattern consistent with genuine service needs rather than indiscriminate overuse. The "high users" are largely individuals with elevated clinical risk who require more frequent monitoring.
• Policy Recommendations:
  • Avoid Universal Restrictions: Broad caps on testing frequency are discouraged as they may penalize high-risk individuals who need frequent surveillance.
  • Differentiated Guidance: The authors advocate for risk-aligned stewardship. This involves providing tailored education and guidance to users based on their risk profiles (e.g., encouraging regular testing for those with multiple partners while offering standard intervals for lower-risk users).
• Equity and Sustainability: By targeting resources and guidance to those with the highest need, the system can maintain sustainability without compromising equity or access for vulnerable populations. The study demonstrates that digital STI testing is a viable, scalable tool for public health when managed through data-driven, risk-stratified strategies.