Patient recruitment is one of the most persistent challenges in clinical research. Nearly half of clinical trial sites miss enrollment deadlines, while 11% fail to recruit even a single patient. At the same time, diversity gaps remain significant— for instance, in cardiovascular disease trials where only 30% of participants are women.
In a recent Xtalks webinar hosted by SubjectWell, our experts shared how innovative recruitment approaches are helping sponsors, CROs, and sites reach “invisible” patients—those who are undiagnosed, misdiagnosed, underrepresented, or disconnected from the healthcare system.
Defining the invisible patient
As Suzanne Harris explained, invisible patients can include:
- Individuals without a formal diagnosis
- Those reluctant to report symptoms due to stigma
- Patients with complex conditions
- Populations historically underrepresented in research
Reaching these groups requires more than traditional site outreach. It demands digital engagement, thoughtful creative, robust patient data, and patient-centric services that ensure participation is accessible and sustainable.
Case study 1: Closing gaps in depression research
Dr. Tobias Kruse described a rescue scenario in Germany where a university hospital was struggling to recruit patients for a depression study. After 13 months, only 200190 participants had enrolled, which was nowhere near the 500 needed.
SubjectWell implemented a digital recruitment campaign that included:
- Social media and search ads (tested in both static image and video formats)
- A dedicated landing page with online pre-qualification
- Patient companion services for patient scheduling for sites, follow-up, and support
The results were striking:
- 46% of total enrollment came through digital recruitment within 6 months, rescuing the study and bringing it to completion
- Video ads outperformed image ads by 35–40% in cost efficiency
- Patient profiles recruited online matched those from traditional sites across age, gender, and severity
- Importantly, digital outreach identified “under-the-radar” patients—highly suicidal individuals with minimal contact with the healthcare system, who would never have been reached through site-based recruitment alone
This study, published in JMIR Mental Health, introduced a new dimension of patient diversity beyond demographics: clinical invisibility.
Case study 2: Shedding light on women’s health
Dr. Matthias Roos presented findings from a collaboration with Bionorica on a real-world evidence (RWE) study on primary dysmenorrhea (severe menstrual pain). While PMS (Premenstrual Syndrome) is well known in the public, dysmenorrhea is not. It’s often mistaken for PMS in the public and is widely underdiagnosed. The team ran an 8-week pre-assessment RWE project (“Patient Feasibility Study”), including a 2-week online campaign to assess online recruitment feasibility.
Through digital campaigns, SubjectWell engaged over 3,200 women affected by dysmenorrhea in just two weeks. The results were striking: only 5% of women affected by the condition have been diagnosed. That is: only 1 in 20 women suffering from dysmenorrhea can be reached through site-based recruitment efforts.
Key insights included:
- 73% had never sought medical advice despite experiencing severe pain
- Only 5% had a formal diagnosis of dysmenorrhea, and 5% are diagnosed with PMS
- Engagement levels were remarkably high, with 97% of participants completing an 18-question survey
- Cost per eligible patient was around €37 (~$40), highlighting cost-efficiency at scale for a patient recruitment campaign in the planned clinical trial
The study demonstrated how digital outreach can uncover large patient populations overlooked by traditional pathways—patients who are symptomatic but undiagnosed and therefore absent from clinical sites.
The bigger picture
Together, these studies prove that:
- Digital recruitment delivers comparable patient profiles to traditional site recruitment
- Creative design choices matter—video formats significantly improve efficiency
- Invisible patients can be reached, improving trial diversity and accelerating timelines
- Patient Feasibility studies using digital methods can help sponsors planning global trials understand their target patient population and provide rapid, cost-effective insights for recruitment feasibility
“We now have scientific proof that digital recruitment not only works, but that it expands diversity, efficiency, and access in ways traditional methods simply cannot.”
