Methods

The Lc65+ cohort is an observational population-based study.

It started in 2004 when a random sample of the community-dwelling population aged 65 to 70 was drawn in Lausanne city (pre-war generation, born between 1934 and 1938). Half of some 3’000 sampled persons (n=1’564) accepted to participate. The structure of the sample was representative of the target population for a variety of demographic and socioeconomic characteristics.

Following an initial questionnaire filled at enrolment, a baseline face-to-face interview and examination was conducted at the study center in 2005. Thereafter, participants complete a yearly follow-up questionnaire. An appointment is scheduled every third year. To describe the aging process and to better understand frailty, the follow-up is not limited in time.

Yearly questionnaires include a large range of items on health and psychosocial characteristics that may influence the evolution of health and quality of life. Triennal examinations include anthropometric measurements as well as physical (grip strength, walking speed, etc.) and cognitive performance tests.

The Lc65+ cohort was enriched by a second sample in 2009 (war generation, 1’489 participants born between 1939 and 1943) and by a third sample in 2014 (early baby-boom generation, 1’678 participants born between 1944 and 1948) in order to study cohort effects on aging.        

Methodological choices

The main methods in the Lc65+ study are:

• long term observation of subjects, beginning at 65 years, an age when frailty is still unusual, in order to study its initiation and development;

• prospective data collection on a large range of health dimensions, including psycho-social characteristics, in order to investigate the temporal sequence linking frailty, its risk factors, modulators, and outcomes;

• a population approach considering frailty as a central parameter of health in ageing populations that is useful not only for surveillance, but also for the evaluation of preventive interventions.