5 Tips for Conducting Self-Selection Studies for Over-the-Counter Medical Devices

By Rachel Aronchick  

It’s no secret that digital health, connected technologies and other advancements in medical care have rapidly expanded over-the-counter (OTC) access to medical devices for the general public. In fact, during a presentation at the 2024 Human Factors & Ergonomics Society Healthcare Symposium, FDA representatives shared that the Center for Devices and Radiological Health’s (CDRH) human factors (HF) premarket review requests for OTC devices skyrocketed between 2018 and 2023, jumping from 10 to 102.  

This increase in OTC devices provides users more control of their health without a clinical intermediary (i.e., healthcare professional, or HCP). But, with this independence also comes added responsibility for manufacturers and users alike: in the absence of professional guidance or prescriptions, individuals must make correct “self-selection” decisions to determine whether a product is appropriate for their personal use.  

In such a highly regulated field, manufacturers and HFE practitioners typically rely on established guidance documents to plan and execute HFE evaluations and activities that align with regulatory expectations. However, when it comes to applying HFE to OTC devices for submission to CDRH, no formal guidance currently exists. As of January 2025, practitioners must rely on informal communication regarding self-selection requirements communicated via industry presentations and/or written feedback to sponsors.  

Without formal guidance, self-selection studies for OTC devices remain a bit of a mystery to many in terms of study preparation and planning, test execution, data collection and more. This article aims to demystify the process by sharing five practical tips for preparing and conducting self-selection studies of OTC devices. This advice reflects feedback provided by the FDA through various channels, as well as our direct experience planning and conducting dozens of such tests. 

1. Define self-selection criteria. As with any product development effort, it’s fundamental to develop a deep understanding of the product’s users. However, when it comes to self-selection, having clearly defined contraindications (i.e., characteristics or medical conditions that might make someone a “non-intended” product user) is critical, yet it’s something that does not always receive the level of attention it deserves. Understanding such contraindications is key when (1) determining whether participants are intended or non-intended users, (2) categorizing participants’ self-selection decisions based on their health assessment questionnaire (HAQ) responses and (3) developing your commercial labeling and marketing materials (as discussed further below). Without this understanding, you cannot effectively scope out the study, recruit participants and analyze data.  
2. Include self-selection tasks in risk analysis and test method. When it comes to HF validation testing for CDRH submissions, the typical focus is on evaluating all critical tasks (i.e., tasks that, if performed incorrectly or not performed at all, could lead to serious harm). In some cases, non-critical tasks can be excluded from the study’s scope. But what happens when use issues associated with self-selection tasks are deemed non-critical? Due to the nature of OTC products and the absence of a clinical intermediary, the FDA expects self-selection to be evaluated during a test, even if the Sponsor has deemed the associated tasks (and potential use errors) non-critical. In these cases, include self-selection-related line items in your use-related risk analysis, designate them as non-critical (if appropriate) and still include a self-selection activity in your test to complete a thorough evaluation.  
3. Revise participant-facing documentation to eliminate biasing language. The primary goal of a self-selection test is to evaluate whether users can make appropriate “self-selection” decisions in the absence of a clinical intermediary. In other words, without input from an HCP, can the end-user determine if a product is right for them? To avoid biasing the participant, all participant-facing study-related documentation should be carefully reviewed, including the recruiting script, informed consent form and moderator’s guide. For example, informing a participant that the study involves a product intended to treat a particular skin condition could inadvertently bias a participant who does not have any skin conditions to determine that the product is not for them. Instead, we suggest using simple phrasing and describing the product as a “consumer medical product” to allow the participant to independently determine the product’s intended use (and users) during the study session.  
4. Simulate realistic decision-making scenarios. When developing the self-selection activity, it’s important that the “decision making experience” is as representative of actual use as possible. This means presenting participants with the same information they would encounter when purchasing the product, whether that’s physical packaging, an e-commerce listing or an in-app interface. For example, if the product is often purchased at a local pharmacy, provide the participant with the sealed carton. Conversely, if the product is accessed via a smartphone app containing an onboarding/eligibility workflow, enable users to advance through the workflow on a smartphone as they would at home. By replicating the actual context in which users are exposed to a product and make decisions, you can more accurately assess whether they can identify themselves as intended or non-intended users. 
5. Present contraindications clearly on outer labeling. For carton-based OTC products, outer packaging is often the first, and sometimes the only, source of information users have available when deciding whether or not they should use a given product. Furthermore, as informally communicated on a few occasions by the FDA, self-selection studies should focus only on the outer packaging, rather than enabling users to correct any self-selection mistakes based on an IFU contained inside the package. As such, it is critical for study success and, of course, proper use when a product is marketed that all contraindications are displayed prominently and in plain language on the external carton. For example, use clear headings (e.g., “Do not use if…”), avoid medical jargon that the general public might not understand and select the size, color contrast and placement that make the information easy to notice and read.  

As OTC access to medical devices continues to grow, self-selection studies play an increasingly important role in assessing if users can identify and select a given medical device without HCP input. While formal FDA guidance is still pending, manufacturers and HFE practitioners can take proactive steps to design robust, realistic and unbiased studies that meet regulatory expectations.  

Importantly, we recognize that sample size determination and participant recruitment are a particularly nuanced, challenging aspect of self-studies studies and are best discussed on a case-by-case basis. Contact our team for more tailored advice or direct support for strategizing, planning and conducting self-selection studies of OTC medical devices.   

Rachel Aronchick is a Managing Human Factors Specialist at Emergo by UL.