Overview of the study. The Canadian Longitudinal Study on Aging (CLSA) is a 20-year prospective study recruiting a sample of 50,000 men and women between the ages of. Hormone therapy use in the Canadian Longitudinal Study on Aging:. Methods: Baseline data from the Tracking cohort of the Canadian Longitudinal Study on Aging. / Étude longitudinale canadienne sur le vieillissement (ÉLCV) The Canadian Longitudinal Study on Aging (CLSA) is a large,…