Re-engaging an inactive cohort of young adults: Evaluating recruitment for the Kidskin Young Adult Myopia Study

Background: Recent changes in communication technologies, including increased reliance on mobile phones and the internet, may present challenges and/or opportunities to re-engaging inactive study cohorts. We evaluate our ability to recruit participants for the Kidskin Young Adult Myopia Study (KYAMS), a follow-up of the Kidskin Study. Methods: KYAMS participants were recruited from the Kidskin Study, a sun exposure-intervention study for 5-6 year-olds running from 1995 to 1999 with most recent follow-up in 2005. From 2015 to 2019, the KYAMS used mail-outs, phone calls and social media to contact Kidskin Study participants. Multivariable logistic regression was used to identify variables associated with successful contact of a Kidskin Study participant or family member and KYAMS participation. Results: Of 1695 eligible participants, 599 (35.5%) participants (or a family member) were contacted and 303 (17.9%) participated in the KYAMS. KYAMS participation was more likely in those who participated in the 2005 follow-up (odds ratio [OR] = 5.09, 95% confidence interval [CI]: 3.67-7.06) and had a mobile phone number on record (OR = 2.25, CI: 1.57-3.23). Of those contacted, participants who were the first point of contact (OR = 4.84, CI: 2.89-8.10) and who were contacted by letter in the first (OR = 6.53, CI: 3.35-12.75) or second (OR = 5.77, CI: 2.85-11.67) round were more likely to participate in the KYAMS, compared to contact by landline phone. Conclusions: We recruited approximately one-fifth of Kidskin Study participants for the KYAMS. Participants were more likely to participate in the KYAMS if they were contacted directly, rather than through a family member, and if they were contacted by invitation letter. Trial registration: ACTRN12617000812392.