Enrollment, retention, and strategies for including disadvantaged populations in randomized controlled trials: a systematic review protocol oleh Abigail LaPlante, Renata W. Yen, Talia Isaacs, Joanna Crocker, Zsofia Demjen, Danielle Schubbe, Alice M. Kennedy, Jaclyn Engel, Nancy O’Brien, Carla Richters, Marie-Anne Durand