New tool uses eight health metrics to track biological aging

A novel health-assessment tool uses eight metrics derived from a person's physical exam and routine lab tests to characterize biological age. It may be able to predict a person's risk of disability and death better than current health predictors.

University of Washington School of Medicine researchers describe their method in a May 5 Nature Communication paper.

The method, called the Health Octo Tool, might make it possible to identify new factors that affect aging, and to design interventions that prolong life, said the report's first author, Dr. Shabnam Salimi. She is a physician-scientist and acting instructor in the Department of Anesthesiology & Pain Medicine. She is also an investigator at the UW Medicine Healthy Aging & Longevity Research Institute

Current health-assessment methods focus on the effects of individual diseases but fail to consider the interactions among diseases and the impact of minor disorders on overall health, Salimi said.

"An aging-based framework offers a new path to discover biomarkers and therapeutics that target organ-specific or whole-body aging, rather than individual diseases," Salimi said.

The approach is based on a concept of aging called "health entropy." The term applies to the amount of molecular and cellular damage the body has accumulated over time, and how that damage has affected organ and system function. Thus, health entropy could serve as a measure of an individual's overall physical well-being and be translated to describe a person's pace of aging.

The researchers analyzed data from the Baltimore Longitudinal Study on Aging, one of the longest-running studies of adults as they grow older. The data included participants' medical history and the results of their physical exams and medical tests. To validate their new approach, researchers then analyzed the results of two other large studies that traced the health of more than 45,000 adults.

The researchers began by establishing what they called a Body Organ Disease Number. This was based on the number of organ systems, such as cardiovascular, respiratory and central nervous systems, that were affected by disease and whether the individual had experienced cancer or a stroke. This score could range from 1 to 14.

"Our findings demonstrated that organ systems age at different rates, prompting us to develop a Bodily System-Specific Age metric to reflect the aging rate of each organ system and the Bodily-Specific Clock to represent each organ system's intrinsic biological age," Salimi said. "Extending this concept to the whole body, we define the Body Clock as a composite measure of overall intrinsic age and Body Age as the corresponding rate of aging."

Because not all people of the same biological age experience the same functional decline, the researchers also developed what they called a Speed-Body Clock and Speed-Body Age to describe how biological age affects walking speed, a common measure of function in older people. They also created a Disability-Body Clock and Disability Body Age, to gauge how intrinsic aging affects the risk of cognitive and physical disability.

Collectively, these eight metrics - Body Clock, Body Age, system-specific clocks and rates, Speed- and Disability-based clocks - offer a way to view an individual's aging process with information gathered from their medical history, physical exam and test results alone."

Dr. Shabnam Salimi, First Author

Of particular interest was the finding that some conditions that might be considered minor problems, such as untreated hypertension early in life, can have a major effect on aging later, indicating that early treatment of these conditions might have a big impact, Salimi said.

The research team is now developing a digital application that will allow individuals, with their healthcare providers, to determine their body and organ's biological ages and track their rate of aging and assess the effect of lifestyle changes and treatments.

"Whether someone is adopting a new diet, exercise routine or taking longevity-targeting drugs, they will be able to visualize how their body - and each organ system - is responding," she said.

Daniel Raftery, professor of anesthesiology and pain medicine at the UW School of Medicine and director of the Northwest Metabolomics Research Center, and Dr. Luigi Ferrucci, scientific director of the National Institute on Aging, are the senior co-authors of the Nature Communications paper.

The research was supported by a National Institutes of Health grant from the U.S. National Institute on Aging (K01AG059898).