Because the two studies are pedigree-based, available offspring were of varying ages at study entry and contributed differing number of assessments to the analyses at any particular follow-up date. Retention has been equivalent by risk group for both studies. The HR and LR participants in the BRFFS study completed an average of 3.63 ± 0.22 (SE) waves and 4.35 ± 0.22 (SE) waves, respectively. For the CPFFS the HR subjects completed an average of 6.09 ± 0.35 evaluations while LR subjects completed 4.57 ± 0.39 (SE) evaluations. (To date, the CPFFS follow up has been longer so that a larger number of high-risk evaluations have been completed.) All study participants provided informed consent at each follow-up visit.
