RT Journal Article SR Electronic T1 Factors associated with non-participation in one or two follow-up phases in a cohort study of injured adults JF Injury Prevention JO Inj Prev FD BMJ Publishing Group Ltd SP 428 OP 433 DO 10.1136/injuryprev-2012-040685 VO 19 IS 6 A1 John Desmond Langley A1 Rebbecca Lilley A1 Suzanne Wilson A1 Sarah Derrett A1 Ari Samaranayaka A1 Gabrielle Davie A1 Shanthi N Ameratunga A1 Emma H Wyeth A1 Paul Hansen A1 Brendan Hokowhitu YR 2013 UL http://injuryprevention.bmj.com/content/19/6/428.abstract AB Objective To identify factors associated with non-participation at the 12-month and 24-month follow-up phases of a prospective cohort study of injury outcomes. Methods Associations between non-participation at follow-up phases and a range of sociodemographic, injury, health, outcome and administrative factors were examined. Results An individual's non-participation at 12 months did not necessarily mean non-participation at 24 months. Sociodemographic factors were the most salient for non-participation, regardless of the number of follow-up phases or specific phase considered. Conclusions Retention rates in prospective cohort studies of injury outcome may be improved by follow-up of everyone irrespective of previous non-participation, focusing resources to retain men, young adults, indigenous people and those living with people other than family members, and by ensuring that multiple alternative participant contacts are obtained. There is sufficient evidence to be concerned about potential bias given that several of the factors we, and others, have identified as associated with non-participation are also associated with various functional and disability outcomes following injury. This suggests detailed investigations are warranted into the effect non-participation may be having on the estimates for various outcomes.