title: A randomized recruitment intervention trial in Parkinson's disease to increase participant diversity: early stopping for lack of efficacy.
abstract: BACKGROUND
  Failure to include participants of diverse race and ethnicity (i.e. those other than European Caucasian, non-Hispanic) in clinical trials impedes the safe development of new therapies given the potential for racial/ethnicity-related variations in treatment response. Increasing diversity is problematic for low prevalence diseases, where most community-based approaches do not reach those with the disease.
  
  
  OBJECTIVE
  Increase racial/ethnic diversity of participants in a Parkinson's disease therapeutic trial.
  
  
  METHODS
  We incorporated a randomized Ancillary Trial into the multisite National Institute of Neurologic Disorders and Stroke Exploratory Trials in Parkinson's Disease Long-Term Study 1. Movement disorders clinics already participating in long-term trial 1 were eligible and were the unit of randomization and analysis. At least 14% of adult residents over age 55 and living within 30 miles of the eligible site were from a diverse population, or there was a near-by zip code with a highly diverse population. Eligible sites also agreed to be randomized. The intervention was designed to increase community physicians' trust in long-term trial 1 investigators and address recruitment barriers in diverse populations. Primary outcomes included percentage of participants from diverse racial/ethnic groups enrolled in long-term trial 1, and qualitative findings from key informant interviews of the Ancillary Trial investigators and coordinators at the end of the trial.
  
  
  RESULTS
  The Ancillary Trial stopped early for lack of efficacy, conditional power less than 1%. The 17 intervention sites had 12.6% diverse participants compared to 15.6% in 15 control clinics; odds ratio 0.82 (95% confidence interval = 0.32-2.16). In key informant interviews, high enrollers of diverse participants reported more use of existing physician relationships, untargeted community outreach, and extensive efforts to overcome participants' barriers. Low enrollers reported more use of patients in their practices and placed more responsibility for low enrollment on prospective participants.
  
  
  CONCLUSIONS
  The Ancillary Trial included only those with Parkinson's disease. Whether our findings generalize to trials in other low prevalence diseases is unknown.
  
  
  CONCLUSIONS
  Increasing diversity in Parkinson's disease clinical trials requires new paradigms for trial investigator and coordinator interactions with community physicians and prospective trial participants.
authors.affiliation: Division of Biostatistics, The University of Texas School of Public Health at Houston, Houston, TX 77030, USA. Barbara.C.Tilley@uth.tmc.edu
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Tilley
authors.forename: Arch G
authors.initials: AG
authors.lastname: Mainous
authors.forename: Jordan J
authors.initials: JJ
authors.lastname: Elm
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Pickelsimer
authors.forename: Lea H
authors.initials: LH
authors.lastname: Soderstrom
authors.forename: Marvella E
authors.initials: ME
authors.lastname: Ford
authors.forename: Vanessa A
authors.initials: VA
authors.lastname: Diaz
authors.forename: Laura A
authors.initials: LA
authors.lastname: Siminoff
authors.forename: Keith
authors.initials: K
authors.lastname: Burau
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Smith
mesh_terms: D002986:Clinical Trials as Topic; D006801:Humans; D007407:Interviews as Topic; D008875:Middle Aged; D010300:Parkinson Disease / Q000208:ethnology*; D018579:Patient Selection; D011897:Random Allocation; D018401:Sample Size; D014481:United States