DOES SAMPLE ATTRITION DECREASE THE GENERALIZABILITY OF THE FINDINGS IN THE CANDRIVE II COHORT STUDY?

The Candrive II cohort researchers have followed a convenient sample of older drivers, aged 70 and older, for five to seven years. One of the goals of this study consists in developing a risk stratification tool that would help identify unsafe older drivers. The validity of such tools depends on how representative the study sample is. We have demonstrated that the Candrive II sample at baseline was representative of older Canadian driver through demonstration of equivalence on variables extracted from the Canadian Community Health Survey – Healthy Aging (CCHS-HA). At baseline, 928 older drivers (mean age = 76.21 5) volunteered in the Candrive II study with 583 of them remaining 5 years later (mean age = 79.8,). We make again use of the equivalence testing approach to compare Candrive II sample at year 5 to CCHS-HA drivers of the same age.