Executive Summary The Canadian Longitudinal Study on Aging
Background and History
The Canadian Longitudinal Study on Aging (CLSA) is a key component of CIHR’s Canadian Life Long Health Initiative (CLHI) and is a cross-cutting strategic initiative that is part of the CIHR’s strategic 
blueprint. CIHR’s commitment to the CLSA is shown by its investments in the planning and feasibility phases of CLSA development, as well as resources within CIHR dedicated to an Ethics, Legal and Social Issues (ELSI) Committee, a CLSA Steering Committee, and an Executive Director. CIHR has also funded the launch of the baseline data collection of the CLSA beginning in 2009. In addition CIHR is working with potential funding partners to secure long-term investment that will make the CLSA a reality. Indeed, CIHR has invested substantially in the initial governance, development, and implementation of the CLSA. In the fall of 2001, CIHR’s Institute of Aging in partnership with Health Canada held an invitational research symposium, From Cell to Society. As a result of the meeting, a Request for Applications to develop the protocol for the CLSA was officially launched. The research team was selected in 2002 to begin the development of the CLSA.
To realize the strategic vision of the CIHR’s cross cutting initiative, the CLSA has been conceptualized as a national project bringing together major Canadian Universities from across the country as participants in a national research program in Healthy Aging. The CLSA is lead by a principal investigator, two Co-principal investigators and 160 co-investigators and collaborators from across Canada. The CLSA has also formed key collaborations with Statistics Canada, Health Canada and many provincial agencies. Moreover, at every critical stage of its development, the CLSA has undergone multiple international peer-reviews to meet the scientific standard set by the CIHR. In collaboration with Statistics Canada, the CLSA team launched the CLSA pilot study in October 2008.
Introduction
Despite long-standing awareness that the aging process is accompanied by multifaceted changes during an individual’s lifetime, a clear picture of the combined effects of these changes has not yet emerged. The effects of complex interactions among changing biological, psychological, and social factors can take years to manifest and may well have a different impact on tomorrow’s seniors (i.e. the baby boomers) than today’s seniors. The Canadian Longitudinal Study on Aging (CLSA) is a large, national, long-term study of adult development and aging. The longitudinal design and extended follow-up will provide a unique opportunity to examine health transitions and trajectories over time, with the goal of better understanding the complex interplay among the vast array of determinants of health, from gene-environment interactions to transitions to retirement. The CLSA will advance aging research in Canada and enable researchers to move beyond providing a snapshot of the adult Canadian population toward observing and understanding the evolution of diseases, psychological attributes, function, disabilities, and psychosocial processes that frequently accompany aging. The CLSA is a collaboration reflecting the work of the principal investigators, Dr. Parminder Raina (McMaster University, Hamilton), Dr. Christina Wolfson (McGill University, Montreal) and Dr. Susan Kirkland (Dalhousie University, Halifax), together with a multi-disciplinary research team comprising more than 160 researchers from 26 universities across Canada. The study design is informed by the results of several feasibility studies which are available on the CLSA website (http://www.clsa-elcv.ca/en/technical_reports_publications/).
Study Design
The CLSA will consist of a national, stratified, random sample of 50,000 Canadian women and men aged 45 to 85 years at the time of recruitment. Participants will undergo repeated waves of data collection at three-year intervals and will be followed for at least 20 years. Scheduled follow-up visits will be supplemented with an annual, short questionnaire to maintain contact and minimize losses to follow-up. The inclusion of study participants as young as 45 years of age is motivated by the desire to capture mid-life experiences prospectively, since important changes known to influence outcomes later in life may occur during this period. The lower age limit will also permit inclusion of a sample from the baby boom cohort (i.e., those born between 1946 and 1964), who will be 45 to 63 years of age in 2009. The upper limit includes individuals entering their senior years who are making the transition into retirement, those who are already retired, and those who have already reached old age. One of the interests in studying the oldest age group prospectively is to examine transitions into the final years of life. All 50,000 participants will be asked to provide a common set of information on demographic, social, physical/clinical, psychological, economic, and health service untilization aspects relevant to health and aging. Thirty-thousand of the 50,000 participants will also be asked to provide additional in-depth information through physical examinations and biological specimen collection (blood and urine). The remaining 20,000 (the tracking cohort) will be a representative sample of the Canadian population. Collectively, this information will provide provincial level estimates of health determinants, health status, and health system utilization. The CLSA cohort will be recruited from participants of Statistics Canada’s Canadian Community Health Survey (CCHS) on Healthy Aging. The CCHS is a survey conducted by Statistics Canada to produce cross-sectional estimates of health determinants, health status, and health system utilization for health regions and provinces in Canada. There are 10 data collection sites for the CLSA in Vancouver, Victoria, Calgary, Winnipeg, Hamilton, Ottawa, Montréal, Sherbrooke, Halifax, and St. John’s. The study will involve telephone and face-to-face interviews as well as, for 30,000 participants the physical examinations. An important supplement to the data collected during the CLSA will be linkage to health administration databases (e.g., publically funded drug plans, medical services plans, hospitalization, continuing care/long-term care, and/or mortality) to collect complementary information on medication use, health services utilization, and to ascertain deaths and causes of death for members of the CLSA cohort. These linkages will be done in partnership with provincial agencies after obtaining participant consent. The data collected as part of the CLSA will be managed and stored to protect the privacy and confidentiality of each participant. The standards for confidentiality are overseen by the institutional research ethics review boards and CIHR’s Ethical, Legal, and Societal issues (ELSI) committee.
IMPLICATIONS
The ultimate aim of the CLSA is to find ways to improve the health and quality of life of Canadians by better understanding the processes and dimensions of aging. The CLSA will contribute to healthy aging and the maintenance of active, independent lifestyles for all Canadians. Through the voluntary participation of 50,000 persons aged 45 to 85 years, the CLSA will draw on a range of experiences from mid-life to older age. This will create a unique research resource that can be used to gain a better understanding of how the multiple aspects of health and aging, both individually and in combination, have an impact on maintaining health and in the development of disease. It will also provide a research platform from which to conduct other research studies including nested case-control studies. The benefits of the CLSA will be many. The CLSA will contribute to the identification of ways to prevent disease and improve health services. We will develop a better understanding of the impact of non-medical factors such as economic and social changes on individuals as they age. The wealth of data collected will also create new knowledge on the many interrelated biological, clinical, psycho-social, and societal factors that affect healthy aging. Finally, the CLSA will facilitate the rapid adoption of sound research into health practice, programs, and policies thereby producing a strengthened and more responsive health system. More information on the Canadian Longitudinal Study on Aging may be found at its website: http://www.clsa-elcv.ca