New Parameters for Sarcopenia Diagnosis

Summary

Goals

Analyze the accuracy of grip strength and gait speed to identify mortality; compare the association between mortality and sarcopenia defined by EWGSOP1 and EWGSOP2 using the best cut-off point found in the present study and those recommended in the literature and test whether slowness is better than these two definitions for identifying the risk of death in elderly adults.

Methods

A longitudinal study was conducted involving 6,182 people aged 60 years and over who participated in the English Longitudinal Study of Aging. Sarcopenia was defined based on EWGSOP1 and EWGSOP2 using different cut-off points for low muscle strength (LMS). Mortality was analyzed over a 14-year follow-up.

Results

Compared to LMS definitions in the literature (<32, <30, <27, and <26 kg for men; <21, <20, and <16 kg for women), the cut-off point of <36 kg for men (sensitivity = 58.59%, specificity = 72.96%, area under the curve [AUC] = 0.66) and < 23 kg for women (sensitivity = 68.90%, specificity = 59.03%, AUC = 0. 64), as well as a low walking speed (LGS) ≤ 0.8 m/s (sensitivity = 53.72%, specificity = 74.02%, AUC = 0.64) demonstrated the best accuracy for mortality.

Using the cut-off point found in the present study, probable sarcopenia [HR = 1.30 (95% CI: 1.16–1.46)], sarcopenia [HR = 1.48 (95% CI: 1.24–1.78)], and severe sarcopenia [HR = 1.78 (95% CI: 1.49–2.12)] according to EWGSOP2 were better predictors of mortality risk than EWGSOP1. LGS ≤0.8 m/s was a better predictor of mortality risk only when LMS was defined by a low cut-off point.

Conclusions

Using LMS <36 kg for men and <23 kg for women and LGS ≤ 0.8 m/s, EWGSOP2 was the best predictor of mortality risk in older adults.

Comments

Sarcopenia , a clinical syndrome characterized by a progressive and extensive decline in skeletal muscle mass, strength , and function, is widely considered a part of aging. Early diagnosis is extremely important and begins with measuring the grip with a dynamometer.

A recent study by researchers at the Federal University of São Carlos (UFSCar) in the state of São Paulo, Brazil, in collaboration with colleagues at University College London (UCL) in the United Kingdom, concluded that the diagnostic protocol should be changed by raising the cut-off point used for handgrip strength to detect muscle weakness. They say that the new criteria proposed in their article would be better predictors of mortality risk in older adults, allowing health professionals to detect the onset of sarcopenia earlier and with greater precision.

The researchers compared the cut-off points proposed in previous studies on the topic. Their analysis was based on data from the English Longitudinal Study of Aging (ELSA) involving 6,182 men and women aged 60 years and older who were followed for 14 years.

The UFSCar/UCL study was supported by FAPESP and was reported in an article published in the journal Age and Aging.

The researchers took as a reference the diagnostic definitions issued in 2010 and revised in 2019 by the European Working Group on Sarcopenia in Older People (EWGSOP), according to which the cut-off point for handgrip strength is 27 kg for men and 16 kg for women. The article recommends raising it to 36 kg and 23 kg respectively.

“We found that lower cut-off points are not acceptable as predictors of mortality risk. The goal of the new reference values ​​is to detect the risk of death as early as possible. When detected late, interventions such as prescribing dietary changes and resistance exercises are much more difficult to perform. Therefore, it is important that our suggestion is accepted by the scientific community and becomes a new consensus for the diagnosis of sarcopenia,” said Tiago da Silva Alexandre, last author of the article. Alexandre is a professor at the Department of Gerontology at UFSCar and a visiting researcher at UCL.

The lowest cut-off value recommended in 2019 has always been questioned by the academic community. “Other studies had shown that there were problems with the approach to diagnosing sarcopenia, but we were the first to present cut-off points capable of predicting mortality risk and compare them with those in use,” he said.

Through this comparison, researchers were able to understand why the 2019 criteria were not working well. “In addition to failing to predict mortality risk, the way sarcopenia is diagnosed underestimates the prevalence of the condition. We showed that when cutoffs were lower, walking speed was a better metric for assessing risk of death. However, this criterion captures only cases of advanced sarcopenia, for which prevention is no longer possible,” said Maria Claudia Bernardes Spexoto, first author of the article and professor at the Faculty of Health Sciences of the Federal University of Gran Dourados. (FCS-UFGD). ) in the state of Mato Grosso do Sul, Brazil.

Loss of muscle mass, strength and function has broader implications than problems with locomotion, lack of autonomy and risk of falls in older people. “Muscles are associated with many more functions than contracting and producing force. They participate in immune and endocrine processes. For example, they help control certain infections through the immune system. They also help control blood sugar,” Alexandre said.

Therefore, muscle quality as well as mass must be controlled. “The skeletal muscle system participates in several other systems in the body. If older people have good muscle mass and quality, they will have a good old age. There is no doubt about it,” he said.

Death risk

According to the results of the new study, the risk of death for older people with "probable sarcopenia" or pre-sarcopenia, defined by EWGSOP as reduced muscle strength with normal muscle mass, was 30% higher than for non-sarcopenic subjects. The risk of mortality was 48% higher for those with sarcopenia and 78% higher for those with severe sarcopenia.

It should be noted that the study considered mortality from all causes and the results were adjusted for covariates (independent variables) such as sex, age, family income, marital status, education, smoking, alcohol consumption, physical activity, high blood pressure, diabetes, cancer, lung disease, heart disease, stroke, falls, depressive symptoms, memory status, number of medications, and abdominal obesity.

According to Alexandre, the difficulty in predicting the risk of mortality from lower cut-off points is due to the follow-up period of the studies. While previous surveys tracked seniors for up to six years, the follow-up period used by the UFSCa r/UCL team was 14 years.

“The studies that proposed lower limits did not estimate the risk of mortality or used data over very short follow-up periods, so the results were biased,” Alexandre said. “Obviously, people with lower muscle strength die faster, which makes it impossible to accurately identify those who are at risk in the medium and long term.”

Loss of muscle mass, strength and function does not occur overnight but gradually over a period of years. “The natural history of sarcopenia is that it happens slowly, day after day,” he said.

Underestimated prevalence

The impact of the new cuts proposed by the UFSCar/UCL team is significant. Among other things, it will affect sarcopenia prevalence statistics. “Higher cut-off points mean higher prevalence and more patients who need to be screened so that the condition is caught long before it becomes a mortality risk,” Alexandre said.

Differences in the EWGSOP guidelines established in 2010 and 2019 have led to discrepancies in prevalence, ranging between 11% and 27.7% when the former are used and between 4.6% and 13.6%. when the latter are applied.

The researchers calculated higher prevalence values ​​based on cut-off points of 36 kg and 23 kg : 33.9% for presarcopenia, 6.2% for confirmed sarcopenia, and 8.6% for severe sarcopenia . “These are high prevalence rates of a condition that can be managed to improve the quality of life of older people and avoid premature death if diagnosed and treated promptly,” Alexandre said. “We are now planning a new study based on these cut-off points to estimate the prevalence of sarcopenia in Brazilians over 60 years of age.”

New metric

The article on age and aging recommends measuring gait speed and handgrip strength for early diagnosis of sarcopenia. Slowness of gait may predict a risk of frailty in older people.

“However, walking speed is itself a result. Older people only walk very slowly [0.8 m per second or less] when they are already weak. The new cut-off points for the diagnosis of sarcopenia provide us with an early predictor of mortality risk, which is essential for clinical practice,” Alexandre said.