Leveraging social media to promote targeted advertisements and key messaging for optimal recruitment into clinical research

Introduction

Background

Social media, a strategy that embeds transformative technology and targeted messaging, is promising for optimizing recruitment in the clinical research enterprise. Social media can promote efficient clinical trials, support representative clinical research, and benefit research investigators. Not only has social media use proliferated over time, but also its prominence as a recruitment strategy has grown exponentially. Findings from a systematic review of nearly 100 studies, conducted by Darko et al. indicate that 45% of studies exclusively used social media, and 51% used social media in conjunction with other strategies for participant recruitment (1). Of interest is 38% of clinical research teams used social media for under-researched populations (1).

Social media has both strengths and limitations as a recruitment strategy. Among its strengths are cost-effectiveness, efficiency, extensive coverage and reach, rapid recruitment, targeted outreach, and the ability to exchange health and clinical research information (2-5). A notable strength of social media for recruitment is its ability to target potential participants who meet eligibility criteria through tailored advertisements, compared to traditional outreach methods (5). However, a disadvantage is the decreased reach among certain groups due to the digital divide and lags (4,6). Ethical considerations should also be examined when employing social media for recruitment. Such considerations include a lack of privacy, governance, and regulatory guidance (1,5). However, evidence on cost-effectiveness remains mixed and may vary across recruitment environments, platform conditions and among the research’s target population, including under-researched individuals, non-English speakers, and older adults (7).

Facebook, a social media platform owned by Meta Platforms Inc., has been noted for its effectiveness in research engagement. As the largest international social media network, Facebook has over three billion active users, assessed monthly, with approximately 250 million users based in the U.S. in 2024 (8). Social media users expended the most time per day (33 minutes) on Facebook in January 2021 compared to TikTok and Twitter, and remains among the top three most commonly used social media platforms (9,10). Interestingly, young adults, Black individuals, and females are the largest consumers of social media in the U.S. (11,12). In 2025, Facebook usage was highest among adults aged 30–49 years (80%), 50–64 years (74%), 18–29 years (68%), and 65+ years (57%). In contrast, YouTube had higher usage across groups compared to Facebook age trends. By comparison, Instagram and TikTok had decreased usage across the same age trends (10). Nearly 80% of women (compared to 63% of men) and 74% of Black individuals (compared to 70% of White individuals) use Facebook as of 2025 (10). Black women use social media for various reasons, including identification of resources, social interaction, information access, entertainment, as well as social support and community building (11,13,14). In sum, Black individuals and women have elevated social media usage and consumption, whereby further exploration of their experiences and engagement within social media is warranted.

Given its extensive reach and coverage, Facebook has utility as a recruitment strategy within health-related research spanning across health outcomes, among under-researched populations, and challenging environments for recruitment [e.g., coronavirus disease 2019 (COVID-19) pandemic] (1,15,16). Facebook has been identified as more efficacious and cost-effective than print newspapers (17). It has high utility due to its increased coverage and reach, cost-effectiveness, and efficiency. Facebook effectively targets advertisements based on age, location, and/or other keywords. This process uses algorithms in software based on a user’s Facebook profile or interests to generate a list of potential participants for targeted advertisements (17). Facebook’s targeting functionality, as such, makes it a promising recruitment strategy in clinical research.

Rationale and knowledge gap

Facebook remains a widely used social media platform among users, including key populations for research, and continues to grow its user base exponentially. Facebook has also demonstrated promise for recruitment and outreach to individuals who may be interested in research participation. Facebook advertisements have been used in health research and among under-researched populations. Despite the usage and advantages of Facebook advertisements for recruitment, the impact of targeted Facebook advertisements remains poorly understood. Specifically, little is known about the impact of targeted versus general advertisements among Black women. This gap is important because it provides insights into the usability of targeted advertisements in recruiting specific populations and can increase engagement among this key population in research studies.

Objective

This study examined how a key population can be strategically engaged to increase the likelihood of their enrollment in clinical research. Using a convergent parallel mixed-methods design, we concurrently conducted the following: (I) assessed recruitment rates and patterns of Facebook advertisements, a social media-based recruitment method, and (II) explored targeted messaging patterns for optimal recruitment among a key population. It was hypothesized that targeted advertisements would increase recruitment and that recruitment themes would emerge from the qualitative analysis of targeted messaging.

Methods

A convergent parallel mixed-methods study design was utilized to interpret both quantitative and qualitative datasets in conjunction for comparison and integration. As the datasets complemented the same phenomenon of identifying targeted messaging for optimal recruitment among Black women, the datasets were interpreted in complement to one another and analyzed separately (18). Secondary quantitative data analysis evaluated recruitment outcomes of Facebook advertisements used in a large, data analysis proceeded iteratively across multiple time points, with an initial theme identified first and a subsequent review of the data yielding an additional emergent theme from a national clinical trial called Rosie the Chatbot. Qualitative data collection and analysis explored the utilization of targeted messaging for recruitment through in-depth qualitative interviews (n=15). Data analyses were then integrated using a joint display.

Quantitative

Data collection

Data sources included Facebook advertisements from Meta Platforms Inc. (https://www.meta.com), recruitment metrics collected from enrollment tracking, and interest form submissions collected via Qualtrics (https://www.qualtrics.com/) that are housed on a Ripple software system (https://www.ripplescience.com/). The secondary dataset was collated from a clinical trial conducted between 2022 and 2025, which maintained systematic tracking of recruitment metrics, specifically focusing on participant enrollment through Facebook advertisements. All secondary data were cleaned, coded, and analyzed using SPSS software (https://www.ibm.com/spss).

Advertisements

Targeted advertisements included phrases focused on race (i.e., Black women), and general advertisements (i.e., women of color), as displayed in Figure 1. We ran ten advertisements in total, including five general advertisements and five targeted advertisements. Advertisements were posted by the university’s research lab on Facebook over the course of a 1-year period on a non-consecutive basis, with each advertisement displayed for one week. The two advertisement types were identical in platform, timing, exposure length, and baseline audience settings; the primary difference was the wording of the advertisement copy. Targeted advertisements used race-specific language (e.g., “Black women”), whereas general advertisements used broader language (e.g., “women of color”), as shown in Figure 1. All advertisements targeted users located in the U.S. who identified as female, were 18 years or older, and matched one or more Meta-generated interests, including “baby bottle”, “baby food”, “baby powder”, “baby shop employers”, “baby shower”, “childhood”, “infant”, “infant bed”, “infant clothing”, “maternity”, or “mother”. The objective of the advertisement campaign was to view the advertisement with included details about the study, visiting a website to express interest in participating in the study, scheduling an interview, and ultimately enrolling in the study. Participants were referred to the study interest form through the Facebook advertisements. The advertisement campaign was designed to drive traffic to the external interest form, after which those who were interested in participating were contacted to schedule an interview and, if eligible, enroll in the study.

Figure 1

For data preparation, targeted advertisements and general advertisements were combined into a separate single category for the descriptive and statistical analyses. Advertisement type was combined because targeted versus general advertisements had the same exposure length and content.

Cost effectiveness

Facebook advertisement metrics were summarized, including the cost of targeted and general advertisements of recruitment outcomes for all potentially interested participants (i.e., enrolled, interviews scheduled, interest forms submitted). The total cost spent (in USD) included: general advertisements ($114.30) versus targeted advertisements ($162.47). The cost of the advertisements remained the same at the sampling point. Cost-effectiveness ratios were calculated at the individual level as cost per objective achieved (e.g., study enrollment, scheduled interviews, and submitted interest forms). These metrics included cost per participant enrolled, cost per interview scheduled, and cost per interest form submitted.

Recruitment and interest rate

The recruitment rate was based on participants meeting the inclusion criteria who identified as Black women. The recruitment rate and interest rate were descriptively analyzed for targeted and general advertisements. The recruitment rate was calculated as the number of participants recruited into the study divided by the total number of interviews scheduled, and the interest rate was calculated as the number of interviews scheduled divided by the total number of submitted interest forms. A Chi-squared test was conducted to examine the difference in the recruitment rates between targeted and general advertisements.

Engagement

A flowchart illustrating participant engagement and disengagement during the recruitment process is depicted in Figure 2. Engagement included the number of potential participants who completed the interest form, scheduled the interview, and completed the interview. Completion of the interview was defined as enrollment into the study. Disengagement included duplicates (i.e., those who submitted duplicate interest forms), disqualified (i.e., potential scam, baby aged out of study eligibility, not qualified), no response (i.e., those who did not schedule the interview, and no show (i.e., those who did not complete the interview). Disengagement was calculated across these outcomes: duplicates, disqualified, no response, and no show.

Figure 2 Flowchart of participant engagement and disengagement.

Qualitative

Study sample and instrument

Secondary qualitative data analysis from semi-structured interviews were analyzed. Fifteen interviews were conducted in 2025 among community partners who were involved with recruitment in the clinical trial and were 18 years or older. Data were de-identified, and pseudonyms were used. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This study was approved by the Institutional Review Board of the University of Maryland College Park (No. 2251043) and reviewed by the study’s Advisory Board. Informed consent was written and participants were consented. While the original study executed recruitment and retention for a clinical research trial, this study examined areas of interest focused on recruitment patterns, including communication, outreach, and messaging that emerged from the secondary qualitative data analysis.

Analysis

For the secondary analysis, the interviews were already transcribed using a two-step process: initial automatic transcription from Zoom videoconferencing software (https://www.zoom.com/), followed by manual verification from the first author to ensure accuracy with the automatic transcription. Data were analyzed utilizing reflexive thematic analysis, where themes were identified, analyzed, and summarized (19). The steps included: (I) data familiarization, (II) data coding, (III) generating initial themes, (IV) developing and reviewing themes, (V) defining and naming themes, and (VI) analysis writing (19). A codebook, focused on direct meaning and content, was developed for the initial and deductive coding scheme. Inductive codes were added later to describe high-level interpretation and emergent themes generated by participants (20). Data were analyzed through an iterative process: with an initial theme identified first and a subsequent review of the data yielding an additional emergent theme. Both deductive and inductive codes existed in the codebook, which were summarized into salient themes (20). Theoretical coding of concepts was assessed, and salient themes of structure, characteristics, and factors contributing to targeted messaging for recruitment were identified. Data analysis occurred through NVivo software (https://lumivero.com/nvivo/). Memos and reflexive statements were analyzed in tandem through triangulation, supporting study rigor (17).

A series of approaches were conducted to enhance study rigor, including Advisory Board meetings and feedback, debriefing sessions, and member checking. The Advisory Board, composed of experts on recruitment and research engagement, reviewed the interview guide and provided feedback on the preliminary results. The debriefing sessions and member checking were conducted to ensure the strength and credibility of findings. Based on feedback received, the interview guide and preliminary results were refined and adjusted to support the study’s strength and caliber. These approaches helped to ensure the quality and validity of the findings (21).

Integration

As quantitative data and qualitative data complemented each other through convergent parallel analysis, the data were integrated into a joint display. This integration enabled the merging of results for direct comparison and supported a rich exploration of how the results expand upon each other, facilitating further analysis and interpretation (18).

Statistical analysis

Results

Advertisements

Cost effectiveness

The targeted advertisements were nearly two times more cost-effective compared to the general advertisements, across all three objectives (e.g., study enrollment, scheduled interviews, and submitted interest forms). The estimated cost-effectiveness ratios were: cost per participant enrolled (targeted =3.53, general =8.16), cost per interview scheduled (targeted =2.70, general =4.76), and cost per interest form submitted (targeted =0.98, general =1.76). A lower ratio indicates a lower cost per objective achieved.

Recruitment and interest rate

There were slightly higher recruitment rates among those exposed to the targeted advertisements (35%) compared to the general advertisements (27%), as displayed in Table 1, although this difference was not statistically significant (P=0.27). A similar trend followed for the interest rate, with a slightly higher rate among those exposed to the targeted advertisements (44%) compared to the general advertisements (41%), as presented in Table 2. This difference is also not statistically significant (P=0.77) between targeted advertisements and general advertisements.

Engagement

Participant engagement and disengagement during the recruitment process are illustrated in the flowchart (Figure 2). Of note, 60 of 167 were enrolled from the targeted advertisements, and 18 of the 65 were enrolled from the general advertisements. More participants were recruited through their exposure to targeted advertisements (35%) than general advertisements (27%). Disengagement (i.e., no show, no response) from targeted advertisements was 66% compared to general advertisements at 72%. For those exposed to targeted advertisements, disengagement across the recruitment process was: duplicates (2%), disqualified (i.e., scam, baby aged out of study, not qualified) (7%), no response (47%), and no show (8%). For those exposed to general advertisements: duplicates (11%), disqualified (9%), no response (38%), and no show (14%).

Messaging

Through the reflexive thematic analysis, two themes about recruitment messaging emerged: promoting tailored language and advancing accessible language that resonates with the community of focus. The integration of results is presented as a joint display in Table 3. Each participant selected their own pseudonym.

Theme one: tailored communication

Tailored communication aligns better with the community’s needs and values, as evidenced by several participants. Participants emphasized messaging should be aligned with the needs of the values of the community. This messaging can be validated through community feedback and member checking to promote cultural resonance (Table 3). Tailored communication also increases opportunities for engagement by making messages more relevant, and relatable to the community of focus.

“It needs to be interactive, so as you’re communicating and sharing what the goals are, engage them as well”. (Nia)

Tailored communication ensures that information is aligned with participants’ needs, that also makes the message clearer and more effective. As participants described, understanding the message can clarify expectations and goals, and overall enhance a smooth research engagement process.

“Let them be on the same page with you. I think that works out better”. (Martha)

Theme two: accessible language

Even within a tailored approach, we have to ensure that language is accessible and appropriate for all. Language that is accessible and appropriate to the community translates to a broader reach. Using language systems that participants understand can lead to better engagement (Table 3). Shared language reduces hesitancy and fosters a greater sense of approachability and openness to research participation and potential engagement.

“I wonder what it could look like to make sure there are insights that would support accessible communication”. (Diana)

Accessible language should also aim to be understandable and available. As shared by participants, maintaining transparency about a participant’s role, purpose, and responsibilities, as well as the researcher’s, reduces the risk of issues and disinterest in research.

“The bottom line early on, explaining why their help’s needed because I think if things aren’t explicitly explained or conveyed, then that just leaves room to think the worst”. (S.W.)

Discussion

Key findings

We found that targeted advertisements resulted in a modestly higher recruitment and interest rate compared to general advertisements on Facebook. Participants showed greater disengagement through no-shows after interviews were scheduled in the recruitment process for general advertisements compared to targeted advertisements. There were also fewer duplicate interest forms submitted and disqualifications for those exposed to the targeted advertisements compared to general advertisements. This finding underscores the higher visibility of targeted advertisements, which are more likely to generate increased interest and greater research engagement.

Strengths and limitations

The study is among the first to apply a convergent parallel mixed-methods analysis of targeted messaging and advertisements for optimal recruitment into clinical research, specifically focusing on Black women as the key population. It is one among the small but growing number of studies focusing on leveraging targeted social media advertisements in conjunction with tailored messaging to engage key populations in clinical research. One limitation is the lack of insight into Facebook’s algorithm for targeted messaging, which individualizes advertisement exposure. An additional limitation is the potential timing effects that were unaccounted for in the advertisement postings, which may have affected engagement, although we controlled for exposure length and content. Moreover, we were unable to account for this influence, dictating advertising exposure (i.e., frequency, recurrence of advertisements). Another limitation is that we did not analyze the impact of cost variability over time on the recruitment objectives. The focus of this study is solely on Facebook, which limits the generalizability of these study findings to other social media platforms.

Comparison with similar research

Evidence suggested that targeted advertisements were nearly twice as cost-effective for recruitment and expressed interest as general advertisements. This finding is corroborated by other literature supporting the cost-effectiveness of Facebook advertisements for recruitment (22,23).

We did not observe a statistically significant difference in the recruitment rate between the targeted and general advertisements. Literature evidences the effectiveness of Facebook advertisements (16,24). Our study’s smaller sample size may have limited the ability to detect a statistically significant difference between targeted and general advertisements (16,24).

Our findings do point toward public health and clinical relevance for optimizing recruitment outcomes. Qualitative findings suggest that tailored communication, as well as accessible and appropriate language, cultivates greater interest and higher resonance in research participation. These findings underscore the importance of recruitment messaging that resonates culturally and aligns with participants’ language systems, as supported by the existing literature (25-28). Integrated mixed-methods findings suggest that targeted messaging and advertisements produce optimal recruitment among a key population, as evidenced by other scholarship (29,30). Findings offer promise about targeted messaging and advertising to recruit a key population into clinical research, while leveraging social media and personalized language.

Explanations of findings

Optimal and efficient recruitment strategies are relevant for investigators to reduce obstacles in the clinical research enterprise. Clinical trials often face delays or cancellations due to insufficient recruitment, affecting up to 60% of all trials (31). Not only do delays hinder meaningful and impactful research, but they also increase burdens for research participants (32). These burdens are exacerbated when involving under-researched groups, leading to a halt on socially valuable research in the clinical research continuum (33-35). Insights gained from optimal recruitment can serve as a starting point for improving efficiency within the clinical research enterprise. Our study findings have been further contextualized as lessons learned in a published toolkit for research investigators, which provides guidance on integrating social media advertisements, such as Facebook advertisements, into clinical research practice (36).

Implications and actions needed

Recruitment efforts that incorporate targeted messaging have demonstrated better resonance with a key population, thereby boosting recruitment outcomes. From integrated data analysis, tailoring, and appropriate language enhanced recruitment in clinical research with practical significance. Notably and importantly, we saw a modest increase in the utilization of Facebook targeted advertisements with one keyword difference between the advertisements. This points toward the opportunity for Facebook targeted advertisements with more keyword differences and other tailored components (i.e., design, specificity) may yield even greater recruitment and interest. Future work should explore the impact of other keywords in social media advertisements among populations of interest and across various social media platforms. As social media advertisements are further scaled as a recruitment strategy, attention should be given to the trustworthiness of digital communications as a key consideration.

Conclusions

Findings suggest that targeted messaging boosts recruitment for a key population, offering promise for advancing efficient and representative clinical research that can benefit research investigators. While there was modest increase in Facebook targeted advertisements with one keyword difference compared to the general advertisements, there may be greater opportunity for targeted advertisements with more keyword differences and other tailored components (i.e., design, specificity) to yield even greater recruitment and interest. Recruitment strategies with targeted messaging on social media are relevant for investigators to more efficiently increase research engagement in the clinical and public health enterprise.

Acknowledgments

We would like to acknowledge the Advisory Board, the Community THRIVES Laboratory, and Rosie the Chatbot Team for their contributions throughout the study. We would like to thank Pankaj Dipankar for his assistance with figure preparation.

Footnote

Data Sharing Statement: Available at https://mhealth.amegroups.com/article/view/10.21037/mhealth-2026-0011/dss

Peer Review File: Available at https://mhealth.amegroups.com/article/view/10.21037/mhealth-2026-0011/prf

Funding: The study was supported by a research grant from the National Institute on Minority Health and Health Disparities (to Q.C.N. and E.M.N.; grant No. R01MD016037); [in part] by the NINR Intramural Research Program of the National Institutes of Health; and supported [in part] by the Intramural Research Program of the National Institutes of Health (NIH) (No. ZIANR000043; to Q.C.N.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://mhealth.amegroups.com/article/view/10.21037/mhealth-2026-0011/coif). Q.N. reports that the study was supported by a research grant from the National Institute on Minority Health and Health Disparities (No. R01MD016037) and [in part] by the Intramural Research Program of the National Institutes of Health (NIH) (No. ZIANR000043). The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The secondary quantitative analysis received ethics approval and consent to participate from the the Institutional Review Board of the University of Maryland College Parks (No. 1556200) for the clinical trial. The secondary qualitative data analysis received ethics approval and consent from the University of Maryland Institutional Review Board (No. 2251043). Informed consent was written and participants were consented, as approved by the University of Maryland Institutional Review Board.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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