Samuel D Searle

Bio: Samuel D Searle is an academic researcher from Dalhousie University. The author has contributed to research in topics: Population & Medicine. The author has an hindex of 12, co-authored 23 publications receiving 2135 citations. Previous affiliations of Samuel D Searle include University College London & University College London Hospitals NHS Foundation Trust.

A standard procedure for creating a frailty index

Abstract: Background Frailty can be measured in relation to the accumulation of deficits using a frailty index. A frailty index can be developed from most ageing databases. Our objective is to systematically describe a standard procedure for constructing a frailty index.

Transitions in frailty status in older adults in relation to mobility: a multistate modeling approach employing a deficit count.

Abstract: OBJECTIVES: To investigate how changes in frailty status and mortality risk relate to baseline frailty state, mobility performance, age, and sex. DESIGN: Cohort study. SETTING: The Yale Precipitating Events Project, New Haven, Connecticut. PARTICIPANTS: Seven hundred fifty-four community-dwelling people aged 70 and older at baseline followed up at 18, 36, and 54 months. MEASUREMENTS: Frailty status, assessed at 18-month intervals, was defined using a frailty index (FI) as the number of deficits in 36 health variables. Mobility was defined as time in seconds on the rapid gait test, in which participants walked back and forth over a 20-foot course as quickly as possible. Multistate transition probabilities were calculated with baseline frailty, mobility, age, and sex estimated using Poisson and logistic regressions in survivors and those who died, respectively. RESULTS: In multivariable analyses, baseline frailty status and age were significantly associated with changes in frailty status and risk of death, whereas mobility was significantly associated with the frailty but not with mortality. At all values of the FI, participants with better mobility were more likely than those with poor mobility to remain stable or to improve. For example, at 54 months, 20.6% (95% confidence interval (CI)=16�25.2) of participants with poor mobility had the same or fewer deficits, compared with 32.4% (95% CI=27.9�36.9) of those with better mobility. CONCLUSION: A multistate transition model effectively measured the probability of change in frailty status and risk of death. Mobility, age, and baseline frailty were significant factors in frailty state transitions.

Impact of exercise in community-dwelling older adults.

Abstract: Background: Concern has been expressed that preventive measures in older people might increase frailty by increasing survival without improving health. We investigated the impact of exercise on the probabilities of health improvement, deterioration and death in community-dwelling older people. Methods and Principal Findings: In the Canadian Study of Health and Aging, health status was measured by a frailty index based on the number of health deficits. Exercise was classified as either high or low/no exercise, using a validated, self-administered questionnaire. Health status and survival were re-assessed at 5 years. Of 6297 eligible participants, 5555 had complete data. Across all grades of frailty, death rates for both men and women aged over 75 who exercised were similar to their peers aged 65 to 75 who did not exercise. In addition, while all those who exercised had a greater chance of improving their health status, the greatest benefits were in those who were more frail (e.g. improvement or stability was observed in 34% of high exercisers versus 26% of low/no exercisers for those with 2 deficits compared with 40% of high exercisers versus 22% of low/no exercisers for those with 9 deficits at baseline). Conclusions In community-dwelling older people, exercise attenuated the impact of age on mortality across all grades of frailty. Exercise conferred its greatest benefits to improvements in health status in those who were more frail at baseline. The net effect of exercise should therefore be to improve health status at the population level.

Frailty and the risk of cognitive impairment.

Abstract: Aging occurs as a series of small steps, first causing cellular damage and then affecting tissues and organs. This is also true in the brain. Frailty, a state of increased risk due to accelerated deficit accumulation, is robustly a risk factor for cognitive impairment. Community-based autopsy studies show that frail individuals have brains that show multiple deficits without necessarily demonstrating cognitive impairment. These facts cast a new light on the growing number of risk factors for cognitive impairment, suggesting that, on a population basis, most health deficits can be associated with late-life cognitive impairment. The systems mechanism by which things that are bad for the body are likely to be bad for the brain can be understood like this: the burden of health deficits anywhere indicates impaired ability to withstand or repair endogenous and environmental damage. This in turn makes additional damage more likely. If true, this suggests that a life course approach to preventing cognitive impairment is desirable. Furthermore, conducting studies in highly selected, younger, healthier individuals to provide ‘proof of concept’ information is now common. This strategy might exclude the very circumstances that are required for disease expression in the people in whom dementia chiefly occurs (that is, older adults who are often in poor health).

Effect of smoking on the accumulation of deficits, frailty and survival in older adults: A secondary analysis from the Canadian study of health and aging

Abstract: Smoking has adverse effects on a variety of organ systems but little is known about the relationship between smoking and frailty. We aimed to investigate differences in health status between smoking and non smoking older adults. The Canadian Study of Health and Aging, a nationally representative cohort study. Nine thousand and eight community-dwelling men and women age 65 years and over at baseline. Smoking status was determined using a Self-Assessed Risk Factor Questionnaire. Comparisons were made between never smokers, light smokers and heavy smokers with heavy smokers defined as those who smoked 1 pack per day for 20 years or more. A frailty index (FI) generated from 40 self-reported health deficits was also modified to exclude 5 variables that could be directly attributed to smoking (e.g. cough). Decedent information was collected over 10 years. Average FI values increased exponentially with age. For both men and women, heavy smokers were the most frail, light smokers had intermediate frailty status and never smokers were fittest. Modification of the FI did not impact these differences. Heavy smokers had significantly worse mortality than non smokers and higher rates of death in smokers persisted in the oldest old. 120 month survival curves, grouped for age, sex and smoking status showed that male smokers > 75 years had the highest mortality rates. Smoking causes poorer health status at older ages which can be captured by the frailty index. Higher rates of death in smokers persist in the oldest old, with no emergence of “survivors” with fitness or longevity advantages.

Cellular senescence and the senescent secretory phenotype: therapeutic opportunities.

Abstract: Aging is the largest risk factor for most chronic diseases, which account for the majority of morbidity and health care expenditures in developed nations. New findings suggest that aging is a modifiable risk factor, and it may be feasible to delay age-related diseases as a group by modulating fundamental aging mechanisms. One such mechanism is cellular senescence, which can cause chronic inflammation through the senescence-associated secretory phenotype (SASP). We review the mechanisms that induce senescence and the SASP, their associations with chronic disease and frailty, therapeutic opportunities based on targeting senescent cells and the SASP, and potential paths to developing clinical interventions.

Prevalence and 10-Year Outcomes of Frailty in Older Adults in Relation to Deficit Accumulation

Abstract: OBJECTIVES: To evaluate the prevalence and 10-year outcomes of frailty in older adults in relation to deficit accumulation. DESIGN: Prospective cohort study. SETTING: The National Population Health Survey of Canada, with frailty estimated at baseline (1994/95) and mortality follow-up to 2004/05. PARTICIPANTS: Community-dwelling older adults (N=2,740, 60.8% women) aged 65 to 102 from 10 Canadian provinces. During the 10-year follow-up, 1,208 died. MEASUREMENTS: Self-reported health information was used to construct a frailty index (Frailty Index) as a proportion of deficits accumulated in individuals. The main outcome measure was mortality. RESULTS: The prevalence of frailty increased with age in men and women (correlation coefficient=0.955–0.994, P<.001). The Frailty Index estimated that 622 (22.7%, 95% confidence interval (CI)=21.0–24.4%) of the sample was frail. Frailty was more common in women (25.3%, 95% CI=23.2–27.5%) than in men (18.6%, 95% CI=15.9–21.3%). For those aged 85 and older, the Frailty Index identified 39.1% (95% CI=31.3–46.9%) of men as frail, compared with 45.1% (95% CI=39.7–50.5%) of women. Frailty significantly increased the risk of death, with an age- and sex-adjusted hazard ratio for the Frailty Index of 1.57 (95% CI=1.41–1.74). CONCLUSION: The prevalence of frailty increases with age and at any age lessens survival. The Frailty Index approach readily identifies frail people at risk of death, presumably because of its use of multiple health deficits in multidimensional domains.