As mentioned in the original cohort profile,1 strengths of TRAILS include its sample size, the combination of a population-based and a clinical cohort, the breadth of the risk and outcome factors assessed (Table 2), the use of multiple informants and multiple methods, and the homogeneity of the samples with regard to age. In addition to that, we can now add that we managed to maintain high retention rates, even after 10 years (Table 1), and to further enrich the database with additional measures, making it an exceptionally rich source of information. Another strength worth mentioning here concerns the quality of its data repository, which qualified for a Data Seal of Approval (see www.datasealofapproval.org) in 2014.
