Assessment of potential bias from non-participation in a dynamic clinical cohort of long-term childhood cancer survivors: results from the St. Jude Lifetime Cohort Study.

Background To evaluate long-term health outcomes among childhood cancer survivors, St. Jude Children’s Research Hospital (SJCRH) has established the St. Jude Lifetime Cohort (SJLIFE), comprised of adult survivors who undergo risk-directed clinical assessments. As in any human research study, SJLIFE participants are volunteers who may not represent the source population from which they were recruited. A lack of proportional representation could result in biased estimates of exposure-outcome associations. We compared available demographic, disease, and neighborhood level characteristics between participants and the source population to assess the potential for selection bias.