title: Recruitment and enrollment in a randomized clinical trial of mandibular two-implant overdenture.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effectiveness of a promotion campaign for subject recruitment and selection, and reasons of withdrawal from a prospective clinical trial of mandibular two-implant supported overdenture.
  
  
  METHODS
  The subjects of this study were participants in a randomized controlled clinical trial for investigating prognosis of implants and overdentures with attachments. Recruited subjects were classified by gender, age, and participation motives. Withdrawal rate of the participants before and after enrollment were evaluated.
  
  
  RESULTS
  177 patients were recruited and 51 patients were enrolled for the trial. Among them, 40 participants eventually took part in the trial. 116 subjects (65.5%) were recruited by advertisement and 61 (34.5%) were referred by patients of the hospital or local clinics. Regarding recruitment effectiveness, newspaper recruited the largest number of participants. With respect to referral patients, the proportion of our hospital patients was higher (37/61). Subjects in their 70s comprised the largest proportion (22/51). The male to female ratio was similar (25:26). Final withdrawal rate of all subjects were 74.0%. Among the reasons for withdrawal from enrollment (n=126) presence of remaining teeth and lack of motivation were the most common reasons.
  
  
  CONCLUSIONS
  To facilitate recruitment of clinical trial subjects and improve enrollment rate, it is important to obtain a sufficient number of researchers, perform promotion activity with diverse strategies, cooperate with local dentists, increase the research funding, and alleviate subjects' fear against clinical trials by thorough consultation.
authors.affiliation: Department of Prosthodontics, Institute for Clinical Dental Research, KUMC, Korea University, Seoul, Republic of Korea.
authors.forename: Jeong-Yol
authors.initials: JY
authors.lastname: Lee
authors.forename: Min-Soo
authors.initials: MS
authors.lastname: Kim
authors.forename: Ha-Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Sang-Wan
authors.initials: SW
authors.lastname: Shin
keywords: Clinical trial; Enrollment; Mandibular implant overdenture; Recruitment