Table 2.

Barriers and potential mitigation strategies to improve trial participation

Trial stage	Barrier	Potential mitigation strategy
Recruitment	Lack of racial and ethnic diversity	Prespecified goal for recruitment of minority subjects Translate recruitment material into other languages, use of plain language in health literacy materials, tailoring research to community needs Make in-person translators available Build an ethnic and racially diverse recruitment team Partner with community health workers or trusted laypeople Expand recruitment to sites that serve a high proportion of minorities and have had prior success recruiting diverse populations
	Limited comprehension or trust of research	Identify community research advocates or navigators Develop opportunities for learning about research Engage communities in the development process Crowdsourcing for study design, recruitment tactics, consent format Delivery of material via print and video or multimedia format Educational opportunities for potential participants Provide participants their own research data when possible
	Geographic location	Provide or reimburse for transport, accommodations Develop community physician partnerships
	Concerns over research integrity	Electronic and passive data capture Use of biochemical and imaging markers as outcomes Blockchain data monitoring
Screening/enrollment	Burdensome requirements	Simplified study design Short double-blind phase Provide telephone/text/electronic reminders of visits Coordinate medical and research visits Alter study design to reduce inefficiency/waste of participant time via adaptive designs and pragmatic trials
	Concern of receiving placebo	Active treatment comparison Cross-over to treatment after placebo-controlled phase Open-label design
	Limited pool of potential participants	Registries of research-interested PD patients Electronic medical record screening tools Opt-out research consent for whole clinic
	Lack of racial and ethnic diversity	Establish relationships with community groups Identify community research advocates
	Geographical location	Partnering/networking with nonacademic physicians to expand access to research Remote screening via telephone or video conference Enhanced records access through electronic medical records
Retention	Loss of income due to trial participation	Compensation strategies tailored to participants needs (travel, lodging, parking, child/adult care, work leave reimbursement) Reward payments for timely completion of study requirements
	Home/life obligations	Limit in-person evaluations, consider telehealth or virtual research visits Decrease research burden by limiting unnecessary data collection, increasing remote data capture Flexible time of visits, including evenings and weekends