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

Changes in frailty predict social vulnerability among home care clients living in the community followed for ten years

BACKGROUND

Among community dwelling older adults, social vulnerability increases with age. Advanced age alone does not fully explain how or why older adults become more socially vulnerable; frailty may offer a better explanation.

OBJECTIVE

We aimed to understand how change in frailty relates to change in social vulnerability over time.

DESIGN

Retrospective cohort study.

SETTING AND PARTICIPANTS

We analyzed older adults aged 65 years and older from the province of Nova Scotia who accessed publicly funded home care in 2005 and 2008 followed for up to ten years.

MEASUREMENTS

We measured social vulnerability and frailty using indices. Controlling for time constant covariates, multi-level growth modelling was used to evaluate whether within-person changes in frailty were associated with within person changes in social vulnerability, after accounting for between-person differences.

RESULTS

There were 2,791 older adults in the 2005 cohort and 2,741 older adults in the 2008 cohort. Mean age, frailty index and social vulnerability index were 80.6 years (SD 7.5), 0.23 (SD 0.10), 0.22 (SD 0.07) and 80.4 (SD 7.6), 0.23 (SD 0.10), and 0.23 (SD 0.07) for each cohort respectively. After accounting for age, sex and baseline frailty, a 0.1 point increase in change of FI from baseline was associated with a 0.017 (CI 0.016 - 0.019, p < 0.001) increase in SVI in the 2005 cohort and a 0.014 (CI 0.013 - 0.016, p < 0.001) increase in SVI in the 2008 cohort.

CONCLUSIONS

Although social vulnerability tends to remain constant in the absence of increases in frailty, changes in frailty are closely associated with changes in social vulnerability. Incorporating within-person changes in health into quantitative models of late-life social vulnerability may further improve our understanding of how and why some individuals are able to stay in the community despite their vulnerabilities.

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.