Recruitment and retention challenges of underrepresented populations in chronic pain research: A systematic review and evidence-based recommendations.

Luna Vasconcelos Felippe 1 , Kevin Pacheco-Barrios MD, MSc 1 ; Alejandra Cardenas-Rojas MD 1 , Luis Castelo-Branco MD 1 , Emad Shaikh MD 1 and Felipe Fregni MD, PhD 1.

1 Neuromodulation Center and Center for Clinical Research Learning, Spaulding Rehabilitation Hospital and Massachusetts General Hospital, Boston, Massachusetts, USA.

OBJECTIVE: Chronic pain is highly prevalent, and it is associated with significant suffering and disability. It has been reported that chronic pain and its related complications such as opioid use disorders disproportionately impact racial and ethnic minority and socioeconomically disadvantaged adults. Yet, these populations are significantly underrepresented in clinical pain research.

METHODS: We systematically search in Medline, Embase, and Central until October 20th, 2020. We included published reports describing recruitment and retention experiences or strategies for underrepresented individual participation (based on ethnicity, race, low income, or gender criteria) in chronic pain research. Additionally, we included reports describing the underrepresented participants' perspectives regarding participation. We assessed the risk of bias using the Cochrane tool for clinical trials, Newcastle-Ottawa Scale (NOS) for observational studies, and the Joanna Briggs Institute Checklist for qualitative studies. The study-reported themes on research participation were summarized, and the recruitment/retention approaches, outcomes, and strategies were qualitatively synthesized to produce recommendations.

RESULTS: Four studies met inclusion criteria, of which all were observational studies (n=536). The included pain conditions were provoked vulvodynia, osteoarthritis, and musculoskeletal pain. Most participants were women (76.1%). Three studies were from the US and one from England. All the studies focused on recruitment/retention approaches, three of which included multifaceted efforts and community outreach components. Studies reported clinician reluctancy in referring to studies, lower levels of education, lower literacy rates, lower income levels, and having more household dependents as the main barriers for participation. Based on the qualitative synthesis, the following approaches reported recruitment improvements: a) mass mailing, b) snowball sampling, c) partnership with local businesses, d) community outreach activities, and e) multimedia advertising. The successful retention strategies were: a) reminder calls, b) rapport building, and c) incentives (including financial compensation). There was considerable heterogeneity in recruitment and retention outcomes. The included evidence body has moderate risk of bias (average of seven points in NOS).

CONCLUSIONS: In summary, the quantity and quality of available evidence to inform best practices in recruitment, retention, and inclusion of underrepresented populations in clinical pain research are low. We have identified evidence-based strategies that can improve this disparity. However, further efforts to systematically evaluate the success of existing and emergent approaches are needed.

KEYWORDS: Chronic pain, Recruitment science, Recruitment and retention, Recruitment interventions, Disparities, Representation in research.


FUNDING/FINANCIAL SUPPORT: This study is funded by NIH grant R01 AT009491-01A1