Health and social factors key to understanding attrition in longitudinal aging research

Exploring participant attrition in a longitudinal follow-up of older adults: the Global Longitudinal Study of Osteoporosis in Women (GLOW) Hamilton cohort

OBJECTIVE

We explored the magnitude of attrition, its pattern and risk factors for different forms of attrition in the cohort from the Global Longitudinal Study of Osteoporosis in Women.

DESIGN

Prospective cohort study.

SETTING

Participants were recruited from physician practices in Hamilton, Ontario.

PARTICIPANTS

Postmenopausal women aged ≥55 years who had consulted their primary care physician within the last 2 years.

OUTCOME MEASURES

Time to all-cause, non-death, death, preventable and non-preventable attrition.

RESULTS

All 3985 women enrolled in the study were included in the analyses. The mean age of the cohort was 69.4 (SD: 8.9) years. At the end of the follow-up, 30.2% (1206/3985) of the study participants had either died or were lost to follow-up. The pattern of attrition was monotone with most participants failing to return after a missed survey. The different types of attrition examined shared common risk factors including age, smoking and being frail but differed on factors such as educational level, race, hospitalisation, quality of life and being prefrail.

CONCLUSION

Attrition in this ageing cohort was selective to some participant characteristics. Minimising potential bias associated with such non-random attrition would require targeted measures to achieve maximum possible follow-rates among the high-risk groups identified and dealing with specific reasons for attrition in the study design and analysis.

Urban-rural variation in the association between social support availability and cognitive function in middle-aged and older adults: Results from the baseline Tracking Cohort of the Canadian Longitudinal Study on Aging

The purpose of this study was to investigate if and how the associations between social support availability (SSA) and cognitive function varied across urban, rural, and geographical regions in Canada. Data from a population-level sample of community-dwelling adults aged 45-85 years were obtained from the baseline Tracking Cohort of the Canadian Longitudinal Study on Aging. The associations between SSA and two domains of cognitive function, memory and executive function, were analyzed using multilevel regression models. SSA was positively and significantly associated with both executive function and memory. We found SSA had stronger positive associations with executive function among participants living in rural areas compared to urban areas in all geographical regions; however, geographical variation in the associations between SSA and memory were not supported by model results. Understanding how the associations between cognitive function and modifiable risk factors, including SSA, vary across geographical contexts is important for developing policies and programs to support healthy aging.