Modular pooled discovery of synthetic knockin sequences to program durable cell therapies.

Chronic stimulation can cause T cell dysfunction and limit the efficacy of cellular immunotherapies. Improved methods are required to compare large numbers of synthetic knockin (KI) sequences to reprogram cell functions. Here, we developed modular pooled KI screening (ModPoKI), an adaptable platform for modular construction of DNA KI libraries using barcoded multicistronic adaptors. We built two ModPoKI libraries of 100 transcription factors (TFs) and 129 natural and synthetic surface receptors (SRs). Over 30 ModPoKI screens across human TCR- and CAR-T cells in diverse conditions identified a transcription factor AP4 (TFAP4) construct that enhanced fitness of chronically stimulated CAR-T cells and anti-cancer function in vitro and in vivo. ModPoKI's modularity allowed us to generate an ∼10,000-member library of TF combinations. Non-viral KI of a combined BATF-TFAP4 polycistronic construct enhanced fitness. Overexpressed BATF and TFAP4 co-occupy and regulate key gene targets to reprogram T cell function. ModPoKI facilitates the discovery of complex gene constructs to program cellular functions.

Pooled Knockin Targeting for Genome Engineering of Cellular Immunotherapies.

Adoptive transfer of genetically modified immune cells holds great promise for cancer immunotherapy. CRISPR knockin targeting can improve cell therapies, but more high-throughput methods are needed to test which knockin gene constructs most potently enhance primary cell functions in vivo. We developed a widely adaptable technology to barcode and track targeted integrations of large non-viral DNA templates and applied it to perform pooled knockin screens in primary human T cells. Pooled knockin of dozens of unique barcoded templates into the T cell receptor (TCR)-locus revealed gene constructs that enhanced fitness in vitro and in vivo. We further developed pooled knockin sequencing (PoKI-seq), combining single-cell transcriptome analysis and pooled knockin screening to measure cell abundance and cell state ex vivo and in vivo. This platform nominated a novel transforming growth factor ß (TGF-ß) R2-41BB chimeric receptor that improved solid tumor clearance. Pooled knockin screening enables parallelized re-writing of endogenous genetic sequences to accelerate discovery of knockin programs for cell therapies.

Functional CRISPR dissection of gene networks controlling human regulatory T cell identity.

Human regulatory T (Treg) cells are essential for immune homeostasis. The transcription factor FOXP3 maintains Treg cell identity, yet the complete set of key transcription factors that control Treg cell gene expression remains unknown. Here, we used pooled and arrayed Cas9 ribonucleoprotein screens to identify transcription factors that regulate critical proteins in primary human Treg cells under basal and proinflammatory conditions. We then generated 54,424 single-cell transcriptomes from Treg cells subjected to genetic perturbations and cytokine stimulation, which revealed distinct gene networks individually regulated by FOXP3 and PRDM1, in addition to a network coregulated by FOXO1 and IRF4. We also discovered that HIVEP2, to our knowledge not previously implicated in Treg cell function, coregulates another gene network with SATB1 and is important for Treg cell-mediated immunosuppression. By integrating CRISPR screens and single-cell RNA-sequencing profiling, we have uncovered transcriptional regulators and downstream gene networks in human Treg cells that could be targeted for immunotherapies.

CSR-1 Slices a Balance.

CSR-1 is a germline-expressed C. elegans Argonaute protein essential for viability. In this issue of Cell, Gerson-Gurwitz et al. now demonstrate a role for CSR-1 and its slicer activity in downregulating the levels of maternally deposited mRNAs to fine-tune the expression of proteins with critical roles in embryonic cell divisions.

Epigenetic inheritance mediated by coupling of RNAi and histone H3K9 methylation.

Histone post-translational modifications (PTMs) are associated with epigenetic states that form the basis for cell-type-specific gene expression1,2. Once established, histone PTMs can be maintained by positive feedback involving enzymes that recognize a pre-existing histone modification and catalyse the same modification on newly deposited histones. Recent studies suggest that in wild-type cells, histone PTM-based positive feedback is too weak to mediate epigenetic inheritance in the absence of other inputs3-7. RNA interference (RNAi)-mediated histone H3 lysine 9 methylation (H3K9me) and heterochromatin formation define a potential epigenetic inheritance mechanism in which positive feedback involving short interfering RNA (siRNA) amplification can be directly coupled to histone PTM positive feedback8-14. However, it is not known whether the coupling of these two feedback loops can maintain epigenetic silencing independently of DNA sequence and in the absence of enabling mutations that disrupt genome-wide chromatin structure or transcription15-17. Here, using the fission yeast Schizosaccharomyces pombe, we show that siRNA-induced H3K9me and silencing of a euchromatic gene can be epigenetically inherited in cis during multiple mitotic and meiotic cell divisions in wild-type cells. This inheritance involves the spreading of secondary siRNAs and H3K9me3 to the targeted gene and surrounding areas, and requires both RNAi and H3K9me, suggesting that the siRNA and H3K9me positive-feedback loops act synergistically to maintain silencing. By contrast, when maintained solely by histone PTM positive feedback, silencing is erased by H3K9 demethylation promoted by Epe1, or by interallelic interactions that occur after mating to cells containing an expressed allele even in the absence of Epe1. These findings demonstrate that the RNAi machinery can mediate transgenerational epigenetic inheritance independently of DNA sequence or enabling mutations, and reveal a role for the coupling of the siRNA and H3K9me positive-feedback loops in the protection of epigenetic alleles from erasure.

Reprogramming human T cell function and specificity with non-viral genome targeting.

Decades of work have aimed to genetically reprogram T cells for therapeutic purposes1,2 using recombinant viral vectors, which do not target transgenes to specific genomic sites3,4. The need for viral vectors has slowed down research and clinical use as their manufacturing and testing is lengthy and expensive. Genome editing brought the promise of specific and efficient insertion of large transgenes into target cells using homology-directed repair5,6. Here we developed a CRISPR-Cas9 genome-targeting system that does not require viral vectors, allowing rapid and efficient insertion of large DNA sequences (greater than one kilobase) at specific sites in the genomes of primary human T cells, while preserving cell viability and function. This permits individual or multiplexed modification of endogenous genes. First, we applied this strategy to correct a pathogenic IL2RA mutation in cells from patients with monogenic autoimmune disease, and demonstrate improved signalling function. Second, we replaced the endogenous T cell receptor (TCR) locus with a new TCR that redirected T cells to a cancer antigen. The resulting TCR-engineered T cells specifically recognized tumour antigens and mounted productive anti-tumour cell responses in vitro and in vivo. Together, these studies provide preclinical evidence that non-viral genome targeting can enable rapid and flexible experimental manipulation and therapeutic engineering of primary human immune cells.

The Effect of Social Isolation on Sarcopenia: A Longitudinal Study among the Middle-Aged and Older Population in China.

INTRODUCTION: Although social isolation is associated with premature death and somatic and mental diseases, evidence of its long-term effect on sarcopenia is scarce. This study aimed to examine the longitudinal association between social isolation and possible sarcopenia. METHODS: We extracted baseline and 4-year follow-up data from the China Health and Retirement Longitudinal Study and included participants aged 45 years or above. Social isolation was measured by factors including living alone, marital status, frequency of contact with adult children and friends, and participation in social activity. The change in social isolation from baseline to follow-up was classified into stable, progressive, and regressive groups. Possible sarcopenia was detected using the handgrip strength and five-time chair-stand test. Using mixed-effects logistic regression, we studied the effect of baseline isolation and the change in isolation status on possible sarcopenia at a 4-year follow-up. RESULTS: A total of 5,289 participants aged 45-90 years and without possible sarcopenia at baseline were included. After 4 years, possible sarcopenia was detected in 21.7% (1,146/5,289) of the participants. Compared with the low social isolation group, the middle (OR = 1.53, 95% confidence interval [CI] = 1.16-2.04, p = 0.003) and high social isolation groups (OR = 1.65, 95% CI = 1.26-2.18, p < 0.001) were associated with a higher risk of possible sarcopenia. Being not married/cohabiting (OR = 1.58, 95% CI = 1.19-2.10, p = 0.002), lack of contact with children (OR = 1.86, 95% CI = 1.21-2.85, p = 0.004), and lack of social activities (OR = 1.26, 95% CI = 1.04-1.53, p = 0.019) were associated with an increased risk of possible sarcopenia. Compared with the stable social isolation group, the progressive group was associated with a greater risk of possible sarcopenia (OR = 1.51, 95% CI = 1.17-1.95, p = 0.001). CONCLUSIONS: Social isolation is associated with an increased risk of possible sarcopenia. Progressive social isolation further elevates the risk. The most vulnerable groups are middle-aged and older people who live alone, are not socially active, and lack contact with their children.

Determinants of heterochromatic siRNA biogenesis and function.

Endogenous small interfering RNAs (siRNAs) and other classes of small RNA provide the specificity signals for silencing of transposons and repeated DNA elements at the posttranscriptional and transcriptional levels. However, the determinants that define an siRNA-producing region or control the silencing function of siRNAs are poorly understood. Here we show that convergent antisense transcription and availability of the Dicer ribonuclease are the key determinants for primary siRNA generation. Surprisingly, Dicer makes dual contributions to heterochromatin formation, promoting histone H3 lysine 9 methylation independently of its catalytic activity, in addition to its well-known role in catalyzing siRNA generation. Furthermore, sequences in the 3' UTR of an mRNA-coding gene inhibit the ability of siRNAs to promote heterochromatin formation, providing another layer of control that prevents the silencing of protein-coding RNAs. Our results reveal distinct mechanisms that limit siRNA generation to centromeric DNA repeats and prevent spurious siRNA-mediated silencing at euchromatic loci.

Effects of reversible cognitive frailty on disability, quality of life, depression, and hospitalization: a prospective cohort study.

OBJECTIVES: Cognitive frailty, a potentially reversible condition describing the concurrence of physical frailty and mild cognitive impairment (MCI), has been recently proposed to incorporate subjective cognitive decline (SCD), a reversible pre-MCI state with more readily available cognitive reserve, as well as pre-physical frailty. Reversible cognitive frailty has been associated with dementia and mortality. We aimed to examine the association of reversible cognitive frailty with other adverse outcomes including disability, poor quality of life (QOL), depression, and hospitalization. METHODS: This was a cohort study with 1-year follow-up among 735 Chinese community-dwelling older adults with intact cognition. Reversible cognitive frailty was operationalized with the presence of pre-physical or physical frailty identified by the Frailty Phenotype and SCD identified by the simplified SCD questionnaire including four self-report cognitive domains of memory, naming, orientation, and mathematical reasoning. Adverse outcomes included incident Activities of Daily Living (ADL)-Instrumental ADL (IADL) disability, poor physical, mental and overall QOL, depression, and hospitalization over 1-year follow-up. RESULTS: The prevalence of reversible cognitive frailty was 27.8%. Participants with reversible cognitive frailty had higher risk of the incidence of ADL-IADL disability, poor physical QOL, poor mental QOL, poor overall QOL, and depression (Odds Ratios: 1.67-4.38, P < 0.05), but not higher risk of hospitalization over 1-year follow-up. CONCLUSION: Reversible cognitive frailty was not uncommon and associated with incident disability, poor QOL, and depression among community-dwelling older adults. Early identification of reversible cognitive frailty can facilitate targeted interventions and may promote independence in older adults.Supplemental data for this article is available online at http://dx.doi.org/10.1080/13607863.2021.2011835.

Effects of social support on frailty trajectory classes among community-dwelling older adults: The mediating role of depressive symptoms and physical activity.

OBJECTIVES: To investigate whether and how social support influenced frailty progression through depressive symptoms and physical activity. METHODS: Of 1235 community-dwelling older adults enrolled at baseline, 778 (63.0%) undergoing at least one yearly follow-up were included in the final analysis. Data were collected on frailty, social support, depressive symptoms, physical activity and covariates. RESULTS: Two frailty trajectory classes were identified and labeled as alleviated frailty and deteriorated frailty. Subjective support prevented the deterioration of frailty through decreased depressive symptoms, while objective support and support utilization prevented the deterioration of frailty through increased physical activity. CONCLUSIONS: The pathways through which social support ameliorates frailty vary by support types. Subjective support interventions should be included in the multifactorial interdisciplinary management of frailty to address social and psychological vulnerabilities, along with objective support and support utilization interventions addressing physical inactivity.

Social gradient of self-rated health in older people-the moderating/mediating role of sense of community.

BACKGROUND: Social gradients of self-rated health (SRH) of older people are evident in various settings. However, it is not clear whether improving older people's sense of community (SoC) could mitigate the social gradient. METHODS: People aged above 60 in five residential districts of Hong Kong were sampled using multistage sampling (n = 1,793). SoC was measured using the validated eight-item Brief Sense of Community Scale, with each item on a five-point Likert scale, forming a score from 8 to 40. SRH was considered as dichotomous (poor/not poor). Socioeconomic status (SES) was operationalised as monthly income, highest education attainment and self-rated disposable income (defined as whether the older person feel he/she has sufficient income). Causal mediation analysis using four-way decomposition was used to assess whether SoC mediates/moderates the association of SES and poor SRH. RESULTS: A social gradient of poor SRH by all measures of SES was observed [adjusted relative risk (RR) per standard deviation income increase = 0.92; 95% confidence interval (95% CI) 0.88-0.97; RR comparing lowest to highest education= 1.77; 95% CI: 1.48-2.11; RR comparing very insufficient to very sufficient disposable income = 1.74; 95% CI: 1.48-2.05]. Causal mediation analysis showed that SoC interacts with the association of education and SRH, with higher the SoC, stronger the education gradient. CONCLUSIONS: Our findings showed a social gradient of SRH in the older population in Hong Kong. This relationship was moderated by SoC, for which higher SoC is related to stronger SES-SRH gradient.

Effect of an integrated care model for pre-frail and frail older people living in community.

OBJECTIVES: to evaluate the effect of an integrated care model for pre-frail and frail community-dwelling older people. DESIGN: a quasi-experimental design. SETTING AND PARTICIPANTS: we enrolled people aged ≥60 years from a community care project. An inclusion criterion was pre-frailty/frailty, as measured by a simple frailty questionnaire (FRAIL) with a score of ≥1. METHODS: we assigned participants to an intervention group (n = 183) in which they received an integrated intervention (in-depth assessment, personalised care plans and coordinated care) or a control group (n = 270) in which they received a group education session on frailty prevention. The outcomes were changes in frailty, individual domains of frailty ('fatigue', 'resistance', 'ambulation', 'illnesses' and 'loss of weight') and health services utilisation over 12 months. Assessments were conducted at baseline and at the 12-month follow-up. RESULTS: the mean age of the participants (n = 453) at baseline was 76.1 ± 7.5 years, and 363 (80.1%) were women. At follow-up, the intervention group showed significantly greater reductions in FRAIL scores than the control group (P < 0.033). In addition, 22.4% of the intervention and 13.7% of the control participants had reverted from pre-frail/frail to robust status, with the difference reaching significance when the intervention was compared with the control group (odds ratio [OR] 1.6, 95% confidence interval [CI] 1.0-2.4) after adjustments for age, sex, living arrangement/marital status and hypercholesterolemia. For individual domains of frailty, the adjusted OR for improved 'resistance' was 1.7 (95% CI 1.0-2.8). However, no effects were found on reducing use of health services. CONCLUSION: the integrated health and social care model reduced FRAIL scores in a combined population of pre-frail/frail community-dwelling older people attending older people's centres.

Is polypharmacy beneficial or detrimental for older adults with cardiometabolic multimorbidity? Pooled analysis of studies from Hong Kong and Europe.

BACKGROUND: Physicians often prescribe high numbers of medications for managing multiple cardiometabolic diseases. It is questionable whether polypharmacy (concurrent use of five or more medications) is beneficial or detrimental for older adults with cardiometabolic multimorbidity (co-occurrence of two or more diseases). OBJECTIVE: To examine combined effects of multimorbidity and polypharmacy on hospitalization and frailty and to determine whether effect sizes of polypharmacy vary with numbers of cardiometabolic diseases. METHODS: We pooled longitudinal data of community-dwelling older adults in Hong Kong, Israel, and 17 European countries. They completed questionnaires for baseline assessment from 2015 to 2018 and reassessment at 1-2-year follow-up. We performed regression analyses to address the objective. RESULTS: Among 44 818 participants (mean age: 69.6 years), 28.3% had polypharmacy and 34.8% suffered from cardiometabolic multimorbidity. Increased risks of hospitalization and worsening frailty were found in participants with 'multimorbidity alone' [adjusted odds ratio (AOR) 1.10 and 1.26] and 'polypharmacy alone' (AOR 1.57 and 1.68). With 'multimorbidity and 'polypharmacy' combined, participants were not at additive risks (AOR 1.53 and 1.47). In stratified analysis, with increasing numbers of cardiometabolic diseases, associations of polypharmacy with hospitalization and frailty were attenuated but remained statistically significant. CONCLUSION: Polypharmacy is less detrimental, yet still detrimental, for older adults living with cardiometabolic multimorbidity. Physicians should optimize prescription regardless of the number of diseases. Health policymakers and researchers need to consider their interrelationship in hospitalization risk predictions and in developing frailty scales.

Perceptions of Neighborhood Environment, Sense of Community, and Self-Rated Health: an Age-Friendly City Project in Hong Kong.

To examine the relationships between perceptions of neighborhood environment, sense of community, and self-rated heath, we recruited 1798 people aged 60 years and older living in Hong Kong. With reference to the checklist of the essential features of age-friendly cities developed by the World Health Organization, perceptions of neighborhood environment were assessed using a questionnaire covering physical and social environmental domains, which mapped onto "outdoor spaces and buildings," "transportation," "housing," "social participation," "respect and social inclusion," "civic participation and employment," "communication and information," and "community support and health services." Sense of community was measured by the Brief Sense of Community Scale. Self-rated health was assessed by a single question. The relationships between these measures were analyzed using partial correlations, multivariate regression models, and path analyses. The mean age of the participants was 71.7 years; of which 54.3% were women. In multivariate regression models, perceived neighborhood environments were positively associated with sense of community and self-rated health. Among the domains of perceived neighborhood environment, "transportation" and "respect and social inclusion" were the physical and the social environmental domains most strongly associated with sense of community, respectively. In addition, sense of community accounted for part of the relationship between perceived neighborhood environments and self-rated health. The results of this study support the importance of perceived neighborhood environments for the sense that older person has of one's community, and self-rated health of older people which may be enhanced through the improvement of neighborhood environments.

Trajectories of frailty among Chinese older people in Hong Kong between 2001 and 2012: an age-period-cohort analysis.

Background: there is little evidence to suggest that older people today are living in better health than their predecessors did at the same age. Only a few studies have evaluated whether there are birth cohort effects on frailty, an indicator of health in older people, encompassing physical, functional and mental health dimensions. Objectives: this study examined longitudinal trajectories of frailty among Chinese older people in Hong Kong. Methods: this study utilised data from the 18 Elderly Health Centres of the Department of Health comprising a total of 417,949 observations from 94,550 community-dwelling Chinese people aged ≥65 years in one early birth cohort (1901-23) and four later birth cohorts (1924-29, 1930-35, 1936-41, 1942-47) collected between 2001 and 2012, to examine trajectories of the frailty index and how birth cohorts may have contributed to the trends using an age-period-cohort analysis. Results: more recent cohorts had higher levels of frailty than did earlier cohorts at the same age, controlling for period, gender, marital status, educational levels, socioeconomic status, lifestyle and social factors. Older age, being female, widowhood, lower education and smoking were associated with higher levels of frailty. Conclusion: more recent cohorts had higher levels of frailty than did earlier cohorts. Frailty interventions, coupled with early detection, should be developed to combat the increasing rates of frailty in Hong Kong Chinese.

Geriatric syndromes, multimorbidity, and disability overlap and increase healthcare use among older Chinese.

BACKGROUND: Geriatric syndromes, multimorbidity, and disability are prevalent among ageing population. However, no study empirically examined their additive or synergistic effect on healthcare use. The present study aims to estimate overlapping prevalence of geriatric syndromes, multimorbidity, and disability; and to examine associations of these three conditions with healthcare use. METHODS: A cross-sectional study was conducted in community-dwelling older adults aged 60 and above in 12 Hong Kong districts. Pearson's chi-squared test for trend was performed to examine prevalence of geriatric syndromes, multimorbidity, and disability across three age groups (60-69, 70-79, and ≥ 80). Multiple logistic regression was conducted to explore associations of these three conditions with three types of healthcare use (hospital admission, general outpatient clinic and specialist outpatient clinic attendance) respectively. RESULTS: Among 2618 participants, 75.3, 41.8, and 22.5% had geriatric syndromes, multimorbidity, and disability respectively, and 10.4% had all the three conditions. Prevalence of the three conditions and their coexistence significantly increased with age (p for trend < .001). Each condition was independently associated with at least two out of three types of healthcare use. Interestingly, the associations of multimorbidity and disability with specialist outpatient clinic attendance were weakened at older age, while the associations of geriatric syndromes with hospital admission and specialist outpatient clinic attendance were strengthened. Furthermore, the odds of all the three types of healthcare use increased with the number of conditions present (p for trend < .001). CONCLUSIONS: Our findings support that the three conditions overlap and increase healthcare use. Early identification, prevention and intervention targeting older adults living with multiple healthcare needs are necessary.

Reduced Frontal Activations at High Working Memory Load in Mild Cognitive Impairment: Near-Infrared Spectroscopy.

BACKGROUND: Some functional magnetic resonance imaging studies have reported altered activations in the frontal cortex during working memory (WM) performance in individuals with mild cognitive impairment (MCI), but the findings have been mixed. The objective of the present study was to utilize near-infrared spectroscopy (NIRS), an alternative imaging technique, to examine neural processing during WM performance in individuals with MCI. METHODS: Twenty-six older adults with MCI (7 males; mean age 69.15 years) were compared with 26 age-, gender-, handedness-, and education-matched older adults with normal cognition (NC; 7 males; mean age 68.87 years). All of the participants undertook an n-back task with a low (i.e., 0-back) and a high (i.e., 2-back) WM load condition while their prefrontal dynamics were recorded by a 16-channel NIRS system. RESULTS: Although behavioral results showed that the two groups had comparable task performance, neuroimaging results showed that the MCI group, unlike the NC group, did not exhibit significantly increased frontal activations bilaterally when WM load increased. Compared to the NC group, the MCI group had similar frontal activations at low load (p > 0.05 on all channels) but reduced activations at high load (p < 0.05 on 4 channels), thus failing to demonstrate WM-related frontal activations (p < 0.05 on 9 channels). In addition, we found a positive correlation between the left WM-related frontal activations and WM ability primarily in the NC group (rs = 0.42, p = 0.035), suggesting a relationship between frontal hypoactivation and WM difficulties. CONCLUSION: The present findings suggest the presence of frontal dysfunction that is dependent on WM load in individuals with MCI.

Using cardiorespiratory fitness to operationalize vitality: a path analysis on the hierarchical structure of intrinsic capacity.

BACKGROUND: There is a lack of consensus about the operationalization of vitality, which is one of the intrinsic capacity (IC) domains. In particular, no study has investigated whether cardiorespiratory fitness (CRF) can be considered a vitality indicator. OBJECTIVE: To examine whether vitality is the upstream domain of IC, and establish the validity of CRF as a vitality indicator, using maximal oxygen consumption (VO2 max) as a representative. METHODS: 561 older adults from a longitudinal cohort study were included. Variables under consideration were VO2 max, other IC domains, instrumental activities of daily living (IADL), and handgrip strength, which was considered an already validated indicator of vitality. Using handgrip strength as the reference point, path analyses were performed to examine whether VO2 max followed a similar hierarchical structure in predicting change in IADL difficulty through other IC domains. RESULTS: The mean age of the participants was 75.5 years. The path model in which vitality was measured by VO2 max demonstrated adequate fit, which was similar to the model in which vitality was measured by handgrip strength. Regarding the path coefficients, the model using VO2 max demonstrated significant total and indirect effects. Notably, the indirect effect was due to the locomotor domain (standardized coefficient = -0.148, p < .001), but not the cognitive or psychological domain. CONCLUSION: Vitality is the upstream domain of IC. VO2 max can be considered an indicator to operationalize the vitality concept.

The measurement properties and feasibility of FRAIL scale in older adults: A systematic review and meta-analysis.

Frailty is a prevalent condition amongst older adults, significantly affecting their quality of life. The FRAIL tool has been purposefully designed for clinical application by assisting healthcare professionals in identifying and managing frailty-related issues in older adults, making it a preferred choice for assessing frailty across diverse older populations. This review aimed to synthesize the measurement properties and feasibility of FRAIL. Guided by COSMIN guidelines, seven databases were searched from inception to 31 Mar 2023. The measurement properties were extracted for quality appraisal of the populations in the studied samples. Where possible, random-effects meta-analysis and meta-regression were used for quantitative synthesis. Eighteen articles containing 273 tests were drawn from 14 different populations. We found that populations testing for criterion validity had high-quality ratings, while construct validity ratings varied based on health status and geographical region. Test-retest reliability had sufficient quality ratings, while scale agreement had sufficient ratings in only four out of 14 populations tested. Responsiveness ratings were insufficient in seven out of eight populations, with inconsistent ratings in one population. Our analysis of missing data across three articles showed a 16.3% rate, indicating good feasibility of the FRAIL. FRAIL is a feasible tool for assessing frailty of older adults in community settings, with good criterion validity and test-retest reliability. However, more research is needed on construct validity and responsiveness.