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Legault V, Pu Y, Weinans E, Cohen AA. Application of early warning signs to physiological contexts: a comparison of multivariate indices in patients on long-term hemodialysis. FRONTIERS IN NETWORK PHYSIOLOGY 2024; 4:1299162. [PMID: 38595863 PMCID: PMC11002238 DOI: 10.3389/fnetp.2024.1299162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 03/15/2024] [Indexed: 04/11/2024]
Abstract
Early warnings signs (EWSs) can anticipate abrupt changes in system state, known as "critical transitions," by detecting dynamic variations, including increases in variance, autocorrelation (AC), and cross-correlation. Numerous EWSs have been proposed; yet no consensus on which perform best exists. Here, we compared 15 multivariate EWSs in time series of 763 hemodialyzed patients, previously shown to present relevant critical transition dynamics. We calculated five EWSs based on AC, six on variance, one on cross-correlation, and three on AC and variance. We assessed their pairwise correlations, trends before death, and mortality predictive power, alone and in combination. Variance-based EWSs showed stronger correlations (r = 0.663 ± 0.222 vs. 0.170 ± 0.205 for AC-based indices) and a steeper increase before death. Two variance-based EWSs yielded HR95 > 9 (HR95 standing for a scale-invariant metric of hazard ratio), but combining them did not improve the area under the receiver-operating curve (AUC) much compared to using them alone (AUC = 0.798 vs. 0.796 and 0.791). Nevertheless, the AUC reached 0.825 when combining 13 indices. While some indicators did not perform overly well alone, their addition to the best performing EWSs increased the predictive power, suggesting that indices combination captures a broader range of dynamic changes occurring within the system. It is unclear whether this added benefit reflects measurement error of a unified phenomenon or heterogeneity in the nature of signals preceding critical transitions. Finally, the modest predictive performance and weak correlations among some indices call into question their validity, at least in this context.
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Affiliation(s)
- Véronique Legault
- Research Center of the Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Yi Pu
- PRIMUS Research Group, Department of Family Medicine, University of Sherbrooke, Sherbrooke, QC, Canada
| | - Els Weinans
- Copernicus Institute of Sustainable Development, Environmental Science, Faculty of Geosciences, Utrecht University, Utrecht, Netherlands
| | - Alan A. Cohen
- Research Center of the Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
- PRIMUS Research Group, Department of Family Medicine, University of Sherbrooke, Sherbrooke, QC, Canada
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Pridham G, Rutenberg AD. Network dynamical stability analysis reveals key "mallostatic" natural variables that erode homeostasis and drive age-related decline of health. Sci Rep 2023; 13:22140. [PMID: 38092834 PMCID: PMC10719307 DOI: 10.1038/s41598-023-49129-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 12/04/2023] [Indexed: 12/17/2023] Open
Abstract
Using longitudinal study data, we dynamically model how aging affects homeostasis in both mice and humans. We operationalize homeostasis as a multivariate mean-reverting stochastic process. We hypothesize that biomarkers have stable equilibrium values, but that deviations from equilibrium of each biomarker affects other biomarkers through an interaction network-this precludes univariate analysis. We therefore looked for age-related changes to homeostasis using dynamic network stability analysis, which transforms observed biomarker data into independent "natural" variables and determines their associated recovery rates. Most natural variables remained near equilibrium and were essentially constant in time. A small number of natural variables were unable to equilibrate due to a gradual drift with age in their homeostatic equilibrium, i.e. allostasis. This drift caused them to accumulate over the lifespan course and makes them natural aging variables. Their rate of accumulation was correlated with risk of adverse outcomes: death or dementia onset. We call this tendency for aging organisms to drift towards an equilibrium position of ever-worsening health "mallostasis". We demonstrate that the effects of mallostasis on observed biomarkers are spread out through the interaction network. This could provide a redundancy mechanism to preserve functioning until multi-system dysfunction emerges at advanced ages.
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Affiliation(s)
- Glen Pridham
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, B3H 4R2, Canada
| | - Andrew D Rutenberg
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, B3H 4R2, Canada.
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3
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Kim S, Lim A, Jang H, Jeon M. Life-Sustaining Treatment Decision in Palliative Care Based on Electronic Health Records Analysis. J Clin Nurs 2023; 32:163-173. [PMID: 35023248 PMCID: PMC10078701 DOI: 10.1111/jocn.16206] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 11/09/2021] [Accepted: 12/23/2021] [Indexed: 12/14/2022]
Abstract
AIMS AND OBJECTIVES This study sought to explore the present status of life-sustaining treatment decisions in a tertiary hospital to improve the life-sustaining treatment decision-making process. BACKGROUND Life-sustaining treatment decisions are crucial for palliative care because they encompass decisions to withdraw treatments when patients cannot articulate their values and preferences. However, surrogate decisions have settled many life-sustaining treatment cases in South Korea, and this trend is prevalent. DESIGN We conducted a retrospective, descriptive study employing a review of electronic health records. METHODS We extracted and analysed electronic health records of a tertiary hospital. Our inclusion criteria included adult patients who completed life-sustaining treatment forms in 2019. A total of 2,721 patients were included in the analysis. We analysed the decision-maker, the timing of the decision, and patients' health status a week before the decision. We followed the STROBE checklist. RESULTS Among 1,429 deceased patients, those whose families had made life-sustaining treatment decisions totalled 1,028 (70.6%). The median interval between life-sustaining treatment documentation completion to death was three days, more specifically, two days in the family decision group and 5.5 days in the patient decision group. As the decision day neared, there were marked changes in patients' vital signs and laboratory test results, and the need for nursing care increased. CONCLUSIONS Life-sustaining treatment decisions were made when death was imminent, suggesting that the time required to discuss end-of-life care was generally insufficient among patients, family, and healthcare professionals in Korea. RELEVANCE TO CLINICAL PRACTICE Monitoring changes in laboratory test results and symptoms could help screen the patients who need the life-sustaining treatment discussion. As improving the quality of death is imperative in palliative care, institutional efforts, such as clinical ethics support services, are necessary to improve the life-sustaining treatment decision-making process for patients, families, and healthcare providers.
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Affiliation(s)
- Sanghee Kim
- College of Nursing and Mo-Im Kim Nursing Research Institute, Yonsei University, Republic of Korea
| | - Arum Lim
- College of Nursing and Mo-Im Kim Nursing Research Institute, Yonsei University, Republic of Korea
| | - Hyoeun Jang
- College of Nursing and Brain Korea 21 FOUR Project, Yonsei University, Republic of Korea
| | - Misun Jeon
- College of Nursing and Brain Korea 21 FOUR Project, Yonsei University, Republic of Korea
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Cohen AA, Ferrucci L, Fülöp T, Gravel D, Hao N, Kriete A, Levine ME, Lipsitz LA, Olde Rikkert MGM, Rutenberg A, Stroustrup N, Varadhan R. A complex systems approach to aging biology. NATURE AGING 2022; 2:580-591. [PMID: 37117782 DOI: 10.1038/s43587-022-00252-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 06/08/2022] [Indexed: 04/30/2023]
Abstract
Having made substantial progress understanding molecules, cells, genes and pathways, aging biology research is now moving toward integration of these parts, attempting to understand how their joint dynamics may contribute to aging. Such a shift of perspective requires the adoption of a formal complex systems framework, a transition being facilitated by large-scale data collection and new analytical tools. Here, we provide a theoretical framework to orient researchers around key concepts for this transition, notably emergence, interaction networks and resilience. Drawing on evolutionary theory, network theory and principles of homeostasis, we propose that organismal function is accomplished by the integration of regulatory mechanisms at multiple hierarchical scales, and that the disruption of this ensemble causes the phenotypic and functional manifestations of aging. We present key examples at scales ranging from sub-organismal biology to clinical geriatrics, outlining how this approach can potentially enrich our understanding of aging.
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Affiliation(s)
- Alan A Cohen
- PRIMUS Research Group, Department of Family Medicine, University of Sherbrooke, Sherbrooke, Quebec, Canada.
- Research Center on Aging and Research Center of Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Quebec, Canada.
- Butler Columbia Aging Center and Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA.
| | - Luigi Ferrucci
- Intramural Research Program of the National Institute on Aging, Baltimore, MD, USA
| | - Tamàs Fülöp
- Research Center on Aging and Research Center of Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Quebec, Canada
- Department of Medicine, Geriatric Division, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Dominique Gravel
- Department of Biology, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Nan Hao
- Section of Molecular Biology, Division of Biological Sciences, University of California, San Diego, San Diego, CA, USA
| | - Andres Kriete
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA, USA
| | - Morgan E Levine
- Department of Pathology, Yale School of Medicine, New Haven, CT, USA
| | - Lewis A Lipsitz
- Beth Israel Deaconess Medical Center, Hebrew SeniorLife, Hinda and Arthur Marcus Institute for Aging Research, and Harvard Medical School, Boston, MA, USA
| | | | - Andrew Rutenberg
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Nicholas Stroustrup
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Ravi Varadhan
- Department of Oncology, Quantitative Sciences Division, Johns Hopkins University, Baltimore, MD, USA
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Cohen AA, Leung DL, Legault V, Gravel D, Blanchet FG, Côté AM, Fülöp T, Lee J, Dufour F, Liu M, Nakazato Y. Synchrony of biomarker variability indicates a critical transition: Application to mortality prediction in hemodialysis. iScience 2022; 25:104385. [PMID: 35620427 PMCID: PMC9127602 DOI: 10.1016/j.isci.2022.104385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 03/22/2022] [Accepted: 05/05/2022] [Indexed: 12/03/2022] Open
Abstract
Critical transition theory suggests that complex systems should experience increased temporal variability just before abrupt state changes. We tested this hypothesis in 763 patients on long-term hemodialysis, using 11 biomarkers collected every two weeks and all-cause mortality as a proxy for critical transitions. We find that variability-measured by coefficients of variation (CVs)-increases before death for all 11 clinical biomarkers, and is strikingly synchronized across all biomarkers: the first axis of a principal component analysis on all CVs explains 49% of the variance. This axis then generates powerful predictions of mortality (HR95 = 9.7, p < 0.0001, where HR95 is a scale-invariant metric of hazard ratio; AUC up to 0.82) and starts to increase markedly ∼3 months prior to death. Our results provide an early warning sign of physiological collapse and, more broadly, a quantification of joint system dynamics that opens questions of how system modularity may break down before critical transitions.
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Affiliation(s)
- Alan A. Cohen
- PRIMUS Research Group, Department of Family Medicine, University of Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
- Research Center on Aging, Sherbrooke, Quebec J1H 4C4, Canada
- Research Center of Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Diana L. Leung
- PRIMUS Research Group, Department of Family Medicine, University of Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Véronique Legault
- PRIMUS Research Group, Department of Family Medicine, University of Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Dominique Gravel
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - F. Guillaume Blanchet
- Research Center on Aging, Sherbrooke, Quebec J1H 4C4, Canada
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
- Département de mathématique, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
- Département des Sciences de la Santé Communautaires, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada
| | - Anne-Marie Côté
- Department of Medicine, Nephrology Division, University of Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Tamàs Fülöp
- Research Center on Aging, Sherbrooke, Quebec J1H 4C4, Canada
- Department of Medicine, Geriatric Division, University of Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Juhong Lee
- InfoCentre, Centre intégré universitaire de santé et de services sociaux de l’Estrie – Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Frédérik Dufour
- PRIMUS Research Group, Department of Family Medicine, University of Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Quebec J1K 2R1, Canada
| | - Mingxin Liu
- PRIMUS Research Group, Department of Family Medicine, University of Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Yuichi Nakazato
- Division of Nephrology, Hakuyukai Medical Corporation, Yuai Nisshin Clinic, 2-1914-6 Nisshin-cho, Kita-ku, Saitama-City, Saitama 331-0823, Japan
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6
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Ivanov PC. The New Field of Network Physiology: Building the Human Physiolome. FRONTIERS IN NETWORK PHYSIOLOGY 2021; 1:711778. [PMID: 36925582 PMCID: PMC10013018 DOI: 10.3389/fnetp.2021.711778] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 05/21/2021] [Indexed: 12/22/2022]
Affiliation(s)
- Plamen Ch Ivanov
- Keck Laboratory for Network Physiology, Department of Physics, Boston University, Boston, MA, United States.,Harvard Medical School and Division of Sleep Medicine, Brigham and Women's Hospital, Boston, MA, United States.,Bulgarian Academy of Sciences, Institute of Solid State Physics, Sofia, Bulgaria
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