New horizons in frailty identification via electronic frailty indices: early implementation lessons from experiences in England and the United States

Frailty represents an integrative prognostic marker of risk that associates with a myriad of age-related adverse outcomes in older adults. As a concept, frailty can help to target scarce resources and identify subgroups of vulnerable older adults that may benefit from interventions or changes in medical management, such as pursing less aggressive glycaemic targets for frail older adults with diabetes. In practice, however, there are several operational challenges to implementing frailty screening outside the confines of geriatric medicine. Electronic frailty indices (eFIs) based on the theory of deficit accumulation, derived from routine data housed in the electronic health record, have emerged as a rapid, feasible and valid approach to screen for frailty at scale. The goal of this paper is to describe the early experience of three diverse groups in developing, implementing and adopting eFIs (The English National Health Service, US Department of Veterans Affairs and Atrium Health-Wake Forest Baptist). These groups span different countries and organisational complexity, using eFIs for both research and clinical care, and represent different levels of progress with clinical implementation. Using an implementation science framework, we describe common elements of successful implementation in these settings and set an agenda for future research and expansion of eFI-informed initiatives.

Cognitive Aging in Older Breast Cancer Survivors

BACKGROUND

Cancer and cancer treatments may affect aging processes, altering the trajectory of cognitive aging, but the extant studies are limited in their intervals of assessment (two-five years). We studied the cognitive performance of a cohort of survivors and controls aged from 60 to 89 years utilizing cross-sectional cognitive performance data as an indicator of potential aging trajectories and contrasted these trends with longitudinal data collected over two years.

METHODS

Female breast cancer survivors who had been diagnosed and treated at age 60 or older and were 5- to 15-year survivors (N = 328) and non-cancer controls (N = 158) were assessed at enrollment and at 8, 16, and 24 months with standard neuropsychological tests and comprehensive geriatric assessment.

RESULTS

A cross-sectional baseline analysis found the expected inverse association of age with cognition in both groups, with survivors performing lower overall than controls in learning and memory (LM). Younger survivors, i.e., those under 75 years of age, exhibited lower performance in both LM and attention, and processing speed and executive function (APE), compared to controls, with no differences being observed between older survivors and controls, which tracked with deficit accumulation trends.

CONCLUSION

Cognitive differences between the survivors and controls for the LM and APE domains were prominent in younger survivors, as was deficit accumulation, suggesting a mediating effect on cognition. Deficit accumulation may represent a modifiable risk factor in cancer survivorship that may be targeted for prevention and intervention.

Association between major discrimination and deficit accumulation in African American cancer survivors: The Detroit Research on Cancer Survivors Study

BACKGROUND

Discrimination can adversely affect health and accelerate aging, but little is known about these relationships in cancer survivors. This study examines associations of discrimination and aging among self-identified African American survivors.

METHODS

A population-based sample of 2232 survivors 20-79 years old at diagnosis were enrolled within 5 years of breast (n = 787), colorectal (n = 227), lung (n = 223), or prostate (n = 995) cancer between 2017 and 2022. Surveys were completed post-active therapy. A deficit accumulation index measured aging-related disease and function (score range, 0-1, where <0.20 is robust, 0.20 to <0.35 is pre-frail, and 0.35+ is frail; 0.06 is a large clinically meaningful difference). The discrimination scale assessed ever experiencing major discrimination and seven types of events (score, 0-7). Linear regression tested the association of discrimination and deficit accumulation, controlling for age, time from diagnosis, cancer type, stage and therapy, and sociodemographic variables.

RESULTS

Survivors were an average of 62 years old (SD, 9.6), 63.2% reported ever experiencing major discrimination, with an average of 2.4 (SD, 1.7) types of discrimination events. Only 24.4% had deficit accumulation scores considered robust (mean score, 0.30 [SD, 0.13]). Among those who reported ever experiencing major discrimination, survivors with four to seven types of discrimination events (vs. 0-1) had a large, clinically meaningful increase in adjusted deficits (0.062, p < .001) and this pattern was consistent across cancer types.

CONCLUSION

African American cancer survivors have high deficit accumulated index scores, and experiences of major discrimination were positively associated with these deficits. Future studies are needed to understand the intersectionality between aging, discrimination, and cancer survivorship among diverse populations.

Adverse Childhood Experiences and frailty in later life: a prospective population-based cohort study

BACKGROUND

The deficit accumulation method considers the ageing process underlying frailty as a random accumulation of health deficits.

OBJECTIVE

Although Adverse Childhood Experiences (ACE) have consistently been associated with the onset of mental disorders and somatic diseases during adolescence and midlife, it remains unknown whether ACE still exert detrimental health effects in late life. Therefore, we examined cross-sectionally and prospectively the association between ACE and frailty among community-dwelling older people.

DESIGN

Based on the health-deficit accumulation method, a Frailty Index was calculated with values ≥0.25 considered as frail. ACE were measured by a validated questionnaire. The cross-sectional association was examined by logistic regression among 2,176 community dwelling participants aged 58-89 years. The prospective association was examined by Cox-regression among 1,427 non-frail participants during a 17-year follow-up. Interactions with age and sex were tested and analyses were adjusted for potential confounders.

SETTING

The present study was embedded in the Longitudinal Aging Study Amsterdam.

RESULTS

ACE and frailty were positively associated at baseline (OR = 1.88; 95% CI = 1.46-2.42; P = 0.05). Among non-frail participants at baseline (n = 1,427), ACE interacted with age on the prediction of frailty. Stratified analyses showed that a history of ACE only resulted in a higher hazard rate for the incidence of frailty among those aged ≥70 years (HR = 1.28; P = 0.044).

CONCLUSION

Even in the oldest-old, ACE still lead to an accelerated rate of the accumulation of health deficits and therefore contribute to the onset of frailty.

Blood-based biomarkers of frailty in solid tumors: a systematic review

This review examines the current literature to identify biomarkers of frailty across patients with solid tumors. We conducted the systematic review using preferred reporting items for systematic reviews and meta-analysis guidelines (PRISMA). PubMed, Web of Science, and Embase databases were searched from their inception to December 08, 2021, for reports of biomarkers and frailty. Two reviewers independently screened titles, abstracts, and full-text articles. A quality assessment was conducted using NHLBI Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies, and Quality Assessment of Case-Control Studies. In total, 915 reports were screened, and 14 full-text articles were included in the review. Most studies included breast tumors, were cross-sectional in design, and measured biomarkers at baseline or pre-treatment. Frailty tools varied with Fried Frailty Phenotype and the geriatric assessment most frequently used. Increased inflammatory parameters (i.e., Interleukin-6, Neutrophil Lymphocyte Ratio, Glasgow Prognostic Score-2) were associated with frailty severity. Only six studies were rated as good quality using assessment ratings. Together, the small number of studies and heterogeneity in frailty assessment limited our ability to draw conclusions from the extant literature. Future research is needed to identify potential target biomarkers of frailty in cancer survivors that may aid in early detection and referral.

Correlates of Early-Stage Frailty-Sleep, Fitness, Oxidative Stress, and BMI

Frailty reflects a decreased reserve in multiple systems resulting from cumulative decline. Frailty markers should be identified as early as possible to attenuate the loss of reserve. The aim of this study was to identify potentially modifiable correlates of frailty in relatively healthy older adults. Volunteers (n = 122) were recruited from local councils and, based on gender and age, were divided into one group of men aged 77.0 (±5.3), and two groups of women, aged 68.8 (±3.6) and aged 78.4 (±3.4). Frailty was assessed by a Frailty Index. The examined correlates were: physical activity, physical fitness (predicted peak VO₂), sleep quality, oxidative stress (hydrogen peroxide-H₂O₂) and depression. Both groups of women had poor scores on physical fitness compared to women's norms. In order to examine the contribution of each of the potential correlates to explaining the variance of frailty, stepwise regressions were performed for each group separately. Based on the results, none of the suggested correlates significantly explained the variability of frailty in the men. In the younger-aged women, predicted peak VO₂ and sleep quality explained 22.4% of the variability of frailty. In the older women, Body Mass Index (BMI), oxidative stress and sleep quality explained 34.9% of the variance. It is possible that increased aerobic fitness and interventions for improving sleep quality in older, seemingly healthy women will slow down the frailty process. Further research is needed to assess potential correlates of frailty, and to initiate suitable interventions to mitigate the signs of frailty at an early stage.

Association of Frailty Status with Risk of Fall among Middle-Aged and Older Adults in China: A Nationally Representative Cohort Study

OBJECTIVES

To investigate the association between frailty status and risk of fall among middle-aged and older Chinese people.

DESIGN

A nationally representative prospective cohort study.

SETTING AND PARTICIPANTS

The study included 13,877 community-dwelling participants aged 45 years and above from the China Health and Retirement Longitudinal Study.

METHODS

Frailty status was identified by the frailty index of health deficit accumulation. 34 variables at baseline were selected to calculate the frailty index. We excluded participants with incomplete information in construction of the frailty index at baseline. Falls were measured based on the respondents' self-report. We used a logistic regression model to estimate the associations between the frailty status and risk of fall, and subgroup analyses and sensitivity analyses were further conducted.

RESULTS

Of 13,877 participants, 2310 (16.6%) had falls during the observation period. 9027 (65.0%) participants were classified as robust, 4019 (29.0%) participants were classified as pre-frail, and 831 (6.0%) participants were classified as frail. Our results indicated per 0.01 increment in the frailty index was significantly associated with an increased risk of fall among middle-aged and older participants (OR: 1.52, 95%CI: 1.45-1.60). Such association was stronger when frailty was presented as a categorical variable, with an OR of 1.75 (95%CI: 1.59-1.93) for pre-frail and 3.04 (95%CI: 2.60-3.56) for frail. The area under the curve of the logistic model was 0.612 (95%CI: 0.600-0.625). Each 0.01 increment of the frailty index was association with a higher risk of fall among middle-aged (45-59years) participants (OR: 1.44, 95%CI: 1.29-1.60) than among older (≥60 years) participants (OR: 1.28, 95%CI: 1.16-1.41) at baseline (p=0.015 for interaction).

CONCLUSION

Frailty was significantly associated with an increased risk of fall among community-dwelling middle-aged and older people in China. It is necessary to screen and recognize frailty status to prevent falls among middle-aged and older adults.

Beyond the Health Deficit Count: Examining Deficit Patterns in a Deficit-Accumulation Frailty Index

BACKGROUND/OBJECTIVES

Exploring deficit patterns among frail people may reveal subgroups of different prognostic importance.

DESIGN

Analysis of National Health and Aging Trends Study.

SETTING

Community.

PARTICIPANTS

Community dwelling older adults with mild to moderate frailty (deficit-accumulation frailty index (FI) of 0.25-0.40) (n = 1821).

MEASUREMENTS

Latent class analysis identified distinct clinical subgroups based on comorbidity (range: 0-10), National Health and Aging Trends Study dementia classification, and short physical performance battery (SPPB) (range: 0-12). Survival analyses compared 5-year mortality by subgroups.

RESULTS

Three latent classes existed: Class 1 (n = 831, mean FI = 0.30) had 2.7% probable dementia, high comorbidities (mean = 3.6), and low physical impairment (SPPB mean = 9.9); Class 2 (n = 734, mean FI = 0.32) had 6.9% probable dementia, low comorbidities (mean = 2.8), and moderate physical impairment (SPPB mean = 6.2); Class 3 (n = 256, mean FI = 0.34) had 20.7% probable dementia, low comorbidities (mean = 2.4), and high physical impairment (SPPB mean = 2.0). Compared to Class 1, Classes 2 and 3 experienced higher 5-year mortality (C2: 1.28 (95% confidence intervals (CI) = 1.00-1.62); C3: 1.87 (95% CI = 1.29-2.73)).

CONCLUSION

Deficit patterns among the mild-to-moderately frail provide additional prognostic information and highlight opportunities for preventive interventions.

Association between a Deficit Accumulation Frailty Index and Mobility Outcomes in Older Adults: Secondary Analysis of the Lifestyle Interventions and Independence for Elders (LIFE) Study

Frailty is a geriatric syndrome represented by susceptibility to precipitating health events and reduced functional reserve. Frailty can be difficult to measure in clinical practice and research. One approach to approximate frailty is based on a deficit accumulation approach, which assesses a larger number of less specific measures such as the presence of comorbidities, physical or cognitive assessments, and lab tests, and summarizes these as a frailty index. The objective of this study was to develop such an index using the Lifestyle Interventions and Independence for Elders (LIFE) Study and evaluate the validity of the frailty measure derived based on baseline information via its association with the primary outcomes of the trial, namely major mobility disability (MMD) and persistent MMD (pMMD). Further, this study aimed to evaluate the effectiveness of the physical activity intervention among participants based on their baseline frailty score. Subjects in the LIFE Study were evaluated at baseline for demographics, clinical history, and a battery of physical and cognitive functioning assessments. In total, 75 possible deficits were scored either as present (yes/no) or based on each score’s quintiles for score-based assessments. The frailty index was measured as the total sum of deficits divided by the total number of possible deficits on a continuous scale between 0 and 100 (i.e., percent of deficits present). The frailty index was further divided into quintiles for comparison. A proportional hazards model was estimated for the MMD outcome controlling for other baseline information. A data driven approach was also used to determine relevant cut-offs in the frailty index where the trial intervention appeared to be modified. Among 1635 trial participants, the mean frailty index was 30.4 ± 6.6 and normally distributed. Over 2.5 years of average follow-up, 14.6%, 16.5%, 18.6%, 22.6%, and 27.6% of participants experienced MMD in quintiles 1–5, respectively. Each 1-unit increase in the frailty index increased the hazard of MMD by 4% (2–5%), and there was a nearly 2-fold increase in MMD between the highest and lowest frailty quintiles. Using log-rank criteria, a cut-point at the median was identified. Further, iterations tested for a frailty cut-off and indicated a subgroup beyond the 85th percentile wherein the physical activity intervention appeared to be no longer be effective. This internally derived deficit accumulation frailty index was uniquely able to identify individuals at higher risk of MMD and pMMD and showed that along the spectrum of frailty, the physical activity intervention remained effective for the majority of participants.

Accumulation of Deficits as a Key Risk Factor for Cardiovascular Morbidity and Mortality: A Pooled Analysis of 154 000 Individuals

Background

Frailty is associated with higher mortality in individuals at high cardiovascular disease (CVD) risk. We hypothesize that frailty is a more important prognostic factor than CVD risk factors and aim to determine the prognostic value of a cumulative deficit frailty index in patients with or at high risk for CVD.

Methods and Results

We conducted an individual‐level pooled analysis of participants with or at risk for CVD, recruited in 14 multicenter clinical trials. The cumulative deficit index was calculated as the proportion of 26 deficits exhibited. Individuals were categorized as nonfrail, prefrail, or frail if they had indexes of ≤0.1, >0.1 to 0.21, or >0.21, respectively. CVD risk was assessed using the Framingham score. Outcomes included CVD event (new or recurrent myocardial infarction, stroke, or heart failure) and mortality. We studied 154 696 patients (mean age, 70.8 years; 63% men) with median follow‐up of 3.2 years. There were 17 535 CVD events and 15 067 deaths. The frail group (n=13 872) had higher risk of a CVD event (incidence rate ratio, 1.97; 95% CI, 1.85–2.08), all‐cause mortality (hazard ratio, 1.91; 95% CI, 1.79–2.03), and CVD mortality (hazard ratio, 1.91; 95% CI, 1.77–2.05) than the nonfrail group (n=101 343). Associations remained unchanged after adjusting for CVD risk factors. The index statistically outperformed the Framingham score in its ability to discriminate CVD events (C‐statistic, 0.60 [95% CI, 0.60–0.61] versus 0.58 [95% CI, 0.57–0.58], respectively; P<0.001).

Conclusions

In individuals with or at high risk of developing CVD, the cumulative deficit index is associated with increased CVD events and mortality, independent of CVD risk factors, and adds incremental prognostic value.

The impact of frailty and cognitive impairment on quality of life: employment and social context matter

ABSTRACTBackground:How cognitive impairment and frailty combine to impact on older adults' Quality of Life (QoL) is little studied, but their inter-relationships are important given how often they co-occur. We sought to examine how frailty and cognitive impairment, as well as changes in frailty and cognition, are associated with QoL and how these relationships differ based on employment status and social circumstances.

METHODS

Using the Survey of Health, Ageing, and Retirement in Europe data, we employed moderated regression, followed by simple slopes analysis, to examine how the relationships between levels of health (i.e., of frailty and cognition) and QoL varied as a function of sex, age, education, social vulnerability, and employment status. We used the same analysis to test whether the relationships between changes in health (over two years) and QoL varied based on these same moderators.

RESULTS

Worse frailty (b = -1.61, p &lt; .001) and cognitive impairment (b = -0.08, p &lt; .05) were each associated with lower QoL. Increase in frailty (b = -2.17, p &lt; .001) and cognitive impairment (b = -0.25, p &lt; .001) were associated with lower QoL. The strength of these relationships varied depending on interactions with age, sex, education, social vulnerability, and employment status. Higher social vulnerability was consistently associated with lower QoL in analyses examining both static health (b = -3.16, p &lt; .001) and change in health (b = -0.66, p &lt; .001).

CONCLUSIONS

Many predictors of QoL are modifiable, providing potential targets to improve older adults' QoL. Even so, the relationships between health, cognition, and social circumstances that shape QoL in older adults are complex, highlighting the importance for individualized interventions.

Age-Related Whole-Brain Structural Changes in Relation to Cardiovascular Risks Across the Adult Age Spectrum

Background: The brain atrophy and lesion index (BALI) has been developed to assess whole-brain structural deficits that are commonly seen on magnetic resonance imaging (MRI) in aging. It is unclear whether such changes can be detected at younger ages and how they might relate to other exposures. Here, we investigate how BALI scores, and the subcategories that make the total score, compare across adulthood and whether they are related to the level of cardiovascular risks, in both young and old adulthood. Methods: Data were from 229 subjects (72% men; 24-80 years of age) whose annual health evaluation included a routine anatomical MRI examination. A BALI score was generated for each subject from T2-weighted MRI. Differences in the BALI total score and categorical subscores were examined by age and by the level of cardiovascular risk factors (CVRFs). Regression analysis was used to evaluate relationships between continuous variables. Relative risk ratios (RRRs) of CVRF on BALI were examined using a multinomial logistic regression. The area under the receiver operating characteristic (ROC) curve was used to estimate the classification accuracy. Results: Nearly 90% of the participants had at least one CVRF. Mean CVRF scores increased with age (slope = 0.03; r = 0.36, 95% confidence intervals: 0.23-0.48; p < 0.001). The BALI total score was closely related to age (slope = 0.18; r = 0.69, 95% confidence intervals: 0.59-0.78; p < 0.001), as so were the categorical subscores (r's = 0.41-0.61, p < 0.001); each differed by the number of CVRF (t-test: 4.16-14.83, χ 2: 6.9-43.9, p's < 0.050). Multivariate analyses adjusted for age and sex suggested an independent impact of age and the CVRF on the BALI score (for each year of advanced age, RRR = 1.20, 95% CI = 1.11-1.29; for each additional CVRF, RRR = 3.63, 95% CI = 2.12-6.23). The CVRF and BALI association remained significant even in younger adults. Conclusion: The accumulation of MRI-detectable structural brain deficits can be evident from young adulthood. Age and the number of CVFR are independently associated with BALI score. Further research is needed to understand the extent to which other age-related health deficits can increase the risk of abnormalities in brain structure and function, and how these, with BALI scores, relate to cognition.

Sex Differences in Healthspan Predict Lifespan in the 3xTg-AD Mouse Model of Alzheimer's Disease

Mouse models of Alzheimer's disease (AD) exhibit marked differences in life expectancy depending on their genotype and sex. The assessment of frailty could provide a measure of healthspan to facilitate comparisons between different AD models. We used a validated mouse frailty index (FI) assessment tool to explore genotype and sex differences in lifespan and healthspan of 3xTg-AD mice and their B6129F2 wild-type (WT) controls. This tool is based on an approach commonly used in people and quantifies frailty by counting the accumulation of age-related health deficits. The number of deficits in an individual divided by the total number measured yields an FI score theoretically between 0 and 1, with higher scores denoting more frailty. Male 3xTg-AD mice aged 300-600 days had higher FI scores (Mean FI = 0.21 ± 0.03) than either male WT (Mean FI = 0.15 ± 0.01) or female 3xTg-AD mice (Mean FI = 0.10 ± 0.01), and the elevated frailty scores were accompanied by parallel increases in mortality. Frailty increased exponentially with age, and higher rates of deficit accumulation elevated mortality risk in all groups of mice. When mice were stratified by FI score, frailty predicted mortality, at least in females. Therefore, the mouse clinical FI provides a valuable tool for evaluating healthspan in mouse models of AD with different lifespans.

Combined Inflammation and Metabolism Biomarker Indices of Robust and Impaired Physical Function in Older Adults

OBJECTIVES

To determine whether combinations of inflammatory markers are related to physical function.

DESIGN AND SUBJECTS

secondary analysis of baseline of three observational studies of community-dwelling older adults MEASUREMENTS: The baseline data from 3 cohorts of older adults with different health and disease status were employed. Twenty markers of inflammation and metabolism were individually assessed for correlation with usual gait speed and were separated into robust and impairment quartiles. For the robustness and impairment indices, individual markers were selected using step-wise regression over bootstrapping iterations, and regression coefficients were estimated for the markers individually and collectively as an additive score.

RESULTS

We developed a robustness index involving 6 markers and an impairment index involving 8 markers corresponding positively and negatively with gait speed. Two markers, glycine and tumor necrosis factor receptor 1 (TNFR1), appeared only in the robustness index, and TNFR2; regulated on activation, normal T-cell expressed and secreted; the amino acid factor; and matrix metallopeptidase 3; appeared only in the impairment index.

CONCLUSION

Indices of biomarkers were associated with robust and impaired physical performance but differ, in composition suggesting potential biological differences that may contribute to robustness and impairment.

Clustering of geriatric deficits emerges to be an essential feature of ageing - results of a cross-sectional study in Poland

The majority of old people suffer from various clinical conditions that affect health, functioning and quality of life. This research is a part of a cross-sectional, nationwide PolSenior Study that provides a comprehensive assessment of eight geriatric impairments and their co-occurrence in a representative sample (3471 participant aged 65-104 years, mean age 78.3 years) of the old adults living in the community in Poland. The participants were recruited randomly from all administrative regions of Poland by a three-stage, proportional, stratified-by-age group selection process. Eight geriatric conditions were assessed: falls, incontinences, cognitive impairment, mood disorders, vision and hearing impairments, malnutrition, and functional dependence. We showed that the most common deficits causing disability were vision and hearing impairments, and mood disorders, with more than two thirds of the participants presented at least one geriatric deficit. We showed that presence any of the analyzed conditions significantly increased the risk for co-occurrence of other examined weaknesses. The highest prevalence odds ratios were for functional dependence and, respectively: malnutrition (8.61, 95%CI: 4.70-15.80), incontinences (8.0, 95%CI:5.93-10.70), and cognitive impairment (7.22; 95%CI:5.91-8.83). We concluded that the majority of the old people living in the community present various clinical conditions that prompt disability.

Implementation of the mouse frailty index

Frailty is considered a state of high vulnerability for adverse health outcomes for people of the same age. Those who are frail have higher mortality, worse health outcomes, and use more health care services than those who are not frail. Despite this, little is known about the biology of frailty, the effect of frailty on pharmacological or surgical outcomes, and potential interventions to attenuate frailty. In humans, frailty can be quantified using a frailty index (FI) based on the principle of deficit accumulation. The recent development of an FI in naturally ageing mice provides an opportunity to conduct frailty research in a validated preclinical model. The mouse FI has been successfully used across a wide range of applications; however, there are some factors that should be considered in implementing this tool. This review summarises the current literature, presents some original data, and suggests areas for future research on the current applications of the mouse FI, inter-rater reliability of the FI, the effect of observer characteristics and environmental factors on mouse FI scores, and the individual items that make up the FI assessment. The implementation of this tool into preclinical frailty research should greatly accelerate translational research in this important field.

Age-related frailty and its association with biological markers of ageing

BACKGROUND

The relationship between age-related frailty and the underlying processes that drive changes in health is currently unclear. Considered individually, most blood biomarkers show only weak relationships with frailty and ageing. Here, we examined whether a biomarker-based frailty index (FI-B) allowed examination of their collective effect in predicting mortality compared with individual biomarkers, a clinical deficits frailty index (FI-CD), and the Fried frailty phenotype.

METHODS

We analyzed baseline data and up to 7-year mortality in the Newcastle 85+ Study (n = 845; mean age 85.5). The FI-B combined 40 biomarkers of cellular ageing, inflammation, haematology, and immunosenescence. The Kaplan-Meier estimator was used to stratify participants into FI-B risk strata. Stability of the risk estimates for the FI-B was assessed using iterative, random subsampling of the 40 FI-B items. Predictive validity was tested using Cox proportional hazards analysis and discriminative ability by the area under receiver operating characteristic (ROC) curves.

RESULTS

The mean FI-B was 0.35 (SD, 0.08), higher than the mean FI-CD (0.22; SD, 0.12); no participant had an FI-B score <0.12. Higher values of each FI were associated with higher mortality risk. In a sex-adjusted model, each one percent increase in the FI-B increased the hazard ratio by 5.4 % (HR, 1.05; CI, 1.04-1.06). The FI-B was more powerful for mortality prediction than any individual biomarker and was robust to biomarker substitution. The ROC analysis showed moderate discriminative ability for 7-year mortality (AUC for FI-CD = 0.71 and AUC for FI-B = 0.66). No individual biomarker's AUC exceeded 0.61. The AUC for combined FI-CD/FI-B was 0.75.

CONCLUSIONS

Many biological processes are implicated in ageing. The systemic effects of these processes can be elucidated using the frailty index approach, which showed here that subclinical deficits increased the risk of death. In the future, blood biomarkers may indicate the nature of the underlying causal deficits leading to age-related frailty, thereby helping to expose targets for early preventative interventions.

Standard laboratory tests to identify older adults at increased risk of death

BACKGROUND

Older adults are at an increased risk of death, but not all people of the same age have the same risk. Many methods identify frail people (that is, those at increased risk) but these often require time-consuming interactions with health care providers. We evaluated whether standard laboratory tests on their own, or added to a clinical frailty index (FI), could improve identification of older adults at increased risk of death.

METHODS

This is a secondary analysis of a prospective cohort study, where community dwelling and institutionalized participants in the Canadian Study of Health and Aging who also volunteered for blood collection (n = 1,013) were followed for up to six years. A standard FI (FI-CSHA) was constructed from data obtained during the clinical evaluation and a second, novel FI was constructed from laboratory data plus systolic and diastolic blood pressure measurements (FI-LAB). A combined FI included all items from each index. Predictive validity was tested using Cox proportional hazards analysis and discriminative ability by the area under receiver operating characteristic (ROC) curves.

RESULTS

Of 1,013 participants, 51.3% had died by six years. The mean baseline value of the FI-LAB was 0.27 (standard deviation 0.11; range 0.05 to 0.63), the FI-CSHA was 0.25 (0.11; 0.02 to 0.72), and the combined FI was 0.26 (0.09; 0.06 to 0.59). In an age- and sex-adjusted model, with each increment in the FI-LAB, the hazard ratios increased by 2.8% (95% confidence interval 1.02 to 1.04). The hazard ratios for the FI-CSHA and the combined FI were 1.02 (1.01 to 1.03) and 1.04 (1.03 to 1.05), respectively. The FI-LAB and FI-CSHA remained independently associated with death in the face of the other. The areas under the ROC curves were 0.72 for FI-LAB, 0.73 for FI-CSHA and 0.74 for the combined FI.

CONCLUSIONS

An FI based on routine laboratory data can identify older adults at increased risk of death. Additional evaluation of this approach in clinical settings is warranted.

New horizons in frailty: ageing and the deficit-scaling problem

All the current frailty measures count deficits. They differ chiefly in which items, and how many, they consider. These differences are related: if a measure considers only a few items, to define broad risks those items need to integrate across several systems (e.g. mobility or function). If many items are included, the cumulative effect of small deficits can be considered. Even so, it is not clear just how small deficits can be. To better understand how the scale of deficit accumulation might impact frailty measurement, we consider how age-related, subcellular deficits might become macroscopically visible and so give rise to frailty. Cellular deficits occur when subcellular damage has neither been repaired nor cleared. With greater cellular deficit accumulation, detection becomes more likely. Deficit detection can be done by either subclinical (e.g. laboratory, imaging, electrodiagnostic) or clinical methods. Not all clinically evident deficits need cross a disease threshold. The extent to which cellular deficit accumulation compromises organ function can reflect not just what is happening in that organ system, but deficit accumulation in other organ systems too. In general, frailty arises in relation to the number of organ systems in which deficits accumulate. This understanding of how subcellular deficits might scale has implications for understanding frailty as a vulnerability state. Considering the cumulative effects of many small deficits appears to allow important aspects of the behaviour of systems close to failure to be observed. It also suggests the potential to detect frailty with less reliance on clinical observation than current methods employ.