Contemporary options for longitudinal follow-up: lessons learned from a cohort of urban adolescents.

This study reports efforts to locate and survey participants in Project Northland Chicago (PNC), a longitudinal, group-randomized trial of an alcohol preventive intervention for racial/ethnic minority, urban, early-adolescents, 3-4 years following the end of the intervention. Data were collected annually among students from 6th-8th grade and then at age 17-18. Tracking procedures were used to maintain contact with participants and data collection consisted of three phases: (1) Internet- and mail-based surveys; (2) in-school survey administration; and (3) courier service delivery. Contact was lost with 11% of this urban cohort from the end of the PNC intervention activities through these longterm follow-up efforts, as indicated by returned locating postcards. Fifty-three percent of the cohort responded to the survey, the majority completing in Phase 1 of our data collection. Additional school-based and courier-delivery efforts increased our response rate by 11.5%. Costs per completed survey were $118 in Phase 1, $166 in Phase 2, and $440 in Phase 3. This study illustrates that it is possible to track and follow-up a high-risk cohort as they progress through adolescence, even with minimal efforts in intervening years. Lessons learned from this study may inform future efforts to track and collect longitudinal data among high-risk populations.