IBIMA Publishing Pediatrics Research International Journal http://www.ibimapublishing.com/journals/PRIJ/prij.html Vol. 2013 (2013), Article ID 475937, 10 pages DOI: 10.5171/2013.475937 _____________ Cite this Article as: Chia-Yu A. Lin and Carol A. DeMatteo (2013), “The Challenges of Loss to Follow-up in Longitudinal Pediatric Acquired Brain Injury Research: One Research Team’s Experiences,” Pediatrics Research International Journal, Vol. 2013 (2013), Article ID 475937, DOI: 10.5171/2013.475937 Research Article The Challenges of Loss to Follow-up in Longitudinal Pediatric Acquired Brain Injury Research: One Research Team’s Experiences Chia-Yu A. Lin 1 and Carol A. DeMatteo 2 1 CanChild Centre for Childhood Disability Research, McMaster University, Hamilton, Ontario, Canada 2 CanChild Centre for Childhood Disability Research and School of Rehabilitation Science, McMaster University, and McMaster Children’s Hospital, Hamilton, Ontario, Canada Correspondence should be addressed to: Chia-Yu A. Lin; linchia@mcmaster.ca Received 20 July 2013; Accepted 19 August 2013; Published 19 November 2013 Academic Editor: Cathy Catroppa Copyright © 2013 Chia-Yu A. Lin and Carol A. DeMatteo. Distributed under Creative Commons CC-BY 3.0 Abstract The Primary objective of this article is to determine the factors associated with retention of children and adolescents with acquired brain injury (ABI) and their families in two prospective longitudinal cohort studies. The study cohort consists of 192 families with a child with ABI who was admitted to McMaster Children’s Hospital (Hamilton, Ontario, Canada) between November 2001 and December 2003. The first study followed this cohort from discharge to two years post-ABI. After a one-year funding gap, the subsequent study followed the same cohort for another four years, which resulted in up to seven years of follow-up. Strategies adopted by the research team to enhance the retention were reviewed, and the possible impact of attrition on study outcomes was evaluated. At the end of the first two years, 175 of the 192 families (91%) remained; at the end of the succeeding follow-up study, 78 of the 87 participant families (90%) remained. No statistically significant difference in demographics and the variables related to ABI was found between those who were lost to follow-up and those who remained in the study. The results suggested that there is no predictable pattern in participants who are lost to follow- up and those that remain. Proactive steps, such as those retention strategies discussed in the manuscript, should be taken by researchers to address this challenging issue of retention in pediatric ABI longitudinal research. Keywords: Brain Injuries; Child; Longitudinal Studies; Researcher-Subject Relations. Introduction Acquired brain injury (ABI) is a major cause of death and long-term disability among the pediatric population. ABI is defined as damage to the brain that occurs after birth and is not related to a congenital disorder or a degenerative disease; damage may be caused by a traumatic injury or by a non-traumatic cause (Brain Injury Association of America, n.d.). In USA, the annual estimate of traumatic brain injury (TBI) alone in children (aged 0-14) is approximately 448000 (Rutland-Brown et al, 2006). Recovery from pediatric ABI which coincides with the natural