Feelings of fatigue may indicate earlier mortality in older adults

  • An older person’s fatigue levels after undertaking certain activities for a specified amount of time can predict the likelihood that the individual’s death is less than 3 years away.
  • Older adults who scored the highest on the Pittsburgh Fatigability Scale (PFS) were more than twice as likely to die in the following 2.7 years compared to their counterparts who scored lower.
  • The study’s authors administered the Pittsburgh Fatigability Scale to nearly 3,000 participants age 60 or older.

While working on a study over 10 years ago, Dr. Nancy W. Glynn, an associate professor in the Department of Epidemiology at the University of Pittsburgh’s Graduate School of Public Health, realized that researchers and health practitioners lacked a reliable tool for measuring fatigability. She defines fatigability as “whole-body tiredness anchored to quantifiable activities.”

At that time, Dr. Glynn explained to Medical News Today, the tools for measuring fatigue asked individuals general questions like, “How tired are you?” or “How weak do you feel?”

“We really wanted to measure fatigue more precisely in our research projects,” Dr. Glynn said. “When a tool doesn’t exist, you develop it yourself.”

By 2014, Dr. Glynn had developed the Pittsburgh Fatigability Scale (PFS). It is currently available in 12 different languages.

The PFS is a 10-question, self-administered questionnaire that looks at physical and mental tiredness related to activities of fixed intensity and duration in adults age 60 and older. The PFS asks respondents to rate things such as “how fatigued do you feel after taking a brisk walk for an hour?” and “how fatigued do you feel after watching TV for 2 hours?”

Over the last several years, Dr. Glynn and other researchers have conducted several studies using the PFS. Most recently, Dr. Glynn served as lead author on research published in the Journal of Gerontology: Series A, which found that older adults who felt especially fatigued when undertaking multiple activities were more likely to die within the next 3 years.

The researchers say the study is the first to “establish perceived physical fatigability as an indicator of earlier mortality.”

High fatigability linked to earlier death

Dr. Glynn and the other authors of the study looked at about 3,000 participants, ranging in age from 60 to 108, who were participating in the Long Life Family Study. This international study follows family members across two generations. Participants answered the questions on the FPS.

The mean age of participants was 73.5. Over half of the participants were women and 99.5% were white.

Participants rated their fatigue from 0 (no fatigue) to 5 (extreme fatigue) for how they expected to feel following specific activities. Questionnaires with higher scores indicated greater perceived physical fatigability.

Data-collecting work concluded at the end of 2019 to avoid mortality impact from the COVID-19 pandemic. Additionally, the study accounted for factors that might influence mortality, including depression and pre-existing conditions.

On average, each participant provided 2.7 years of data. About 10% of participants died by the end of the follow-up period.

Researchers found respondents who scored 25 points or higher on the PFS were 2.3 times more likely than those who scored below 25 to die in the subsequent 2.7 years after completing the scale.

Chicken or egg?

Initially, Dr. Glynn told MNT, she wasn’t sure of the nature of the relationship between fatigability and mortality.

“It’s very tricky to know if it’s the chicken or the egg,” she said. “Does physical activity impact fatigability, and then people become functionally impaired? […] Or […] is it the other direction? Are you fatigued, or there’s something that’s making you fatigued and then it […] leads to lower physical activity?”

Dr. Glynn and other researchers attempted to answer that question with different research projects, including a 2021 study that found that increased activity levels led to reductions in physical fatigability.

“That definitely points to the fact that physical activity may be a very viable modality to reduce fatigability,” Dr. Glynn told MNT.

According to Dr. Scott Kaiser, director of geriatric cognitive health for the Pacific Neuroscience Institute at Providence Saint John’s Health Center, the good news is that there’s hope for older adults experiencing frequent exhaustion.

“That’s something you can modify, right?” he told MNT. “If you’re out of shape, you can get in shape.”

Dr. Glynn hopes to create activity recipes for individuals looking to increase their stamina.

“My ultimate goal would be to design a physical activity intervention aimed at reducing fatigability so that we really can quantify and pinpoint the type, dose, and frequency needed to reduce fatigability in older adults.”

– Dr. Glynn

The FPS: A solid scale

Dr. Kaiser appreciates the ease of using the PFS in a clinical setting. “It’s feasible, it doesn’t require lots of fancy technology, doesn’t require a heavy lift, and people can tell you how they’re doing.”

In particular, he likes that the scale asks very specific questions. After all, “Do you get tired gardening?” means one thing to a person who typically fusses over flower beds for 7 hours at a stretch and another for the individual who rarely does more than spend 30 minutes mowing a patch of grass.

“This kind of standardizes things,” he said.

Future research to examine more diverse cohort

One limitation of the study is that nearly all participants were white, both Glynn and Dr. Kaiser acknowledged.

“There might be ethnic and cultural components to how people report their fatigue,” Dr. Kaiser told MNT.

With future work, Glynn hopes to look at whether fatiguability predicts a greater risk of death in a more diverse group. “I would think that the result would likely hold in other cohorts,” she said.

A modifiable risk factor

Dr. Glynn hopes her research leads to more healthcare practitioners talking about fatigability.

“It’s largely not addressed by clinicians in physical examinations,” she said. “People shouldn’t have to just live with it.”

Dr. Kaiser added that fatigability is also something individuals should think about when they periodically check in on their bodies to assess their health.

“Being easily fatigued can be added to that list of potential warning signs,” he said. “Then you know it’s time to act.”

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