The Future Prevalence of Sarcopenia in Europe: A Claim for Public Health Action

Sarcopenia is clinically defined as a progressive and generalized loss of skeletal muscle mass and strength: It is the major pathway to physical frailty [1, 2]. Until recently, sarcopenia was considered as a geriatric syndrome but it is now recognized as an independent condition by an International Classification of Disease, Tenth Revision, Clinical Modification (ICD-10-CM), code (i.e., M 62.84) [3]. Over the last decade, definitions of sarcopenia, among researchers, have varied and sometimes were discrepant [4, 5]. In 2010, the European Working Group on Sarcopenia in Older People (EWGSOP) published its recommendations for a clinical definition and consensual diagnosis criteria of sarcopenia [6], which includes a combination of a loss of muscle mass and strength or physical performance. This panel of respected experts suggested an algorithm for sarcopenia case-finding in older individuals based on measurements of gait speed, grip strength and muscle mass [6]. However, prevalence of sarcopenia remains difficult to establish. Indeed, it can differ based on the characteristics of the studied population (e.g., subjects living in nursing homes have a higher prevalence) but can also dramatically change depending on the definition used for the diagnosis of sarcopenia [7]. A major step toward obtaining a more accurate picture of sarcopenia prevalence is that, since 2010, most of the studies have used the EWGSOP consensus as the gold standard to define sarcopenia. However, within the consensual definition, different cutoff points are recommended for the diagnosis of sarcopenia [6]. Two options for each variable (skeletal muscle mass index, muscle strength and physical performance including more specifically gait speed) are suggested to define subnormal values. Subsequently, in subjects aged 65 years and older, prevalence of sarcopenia may differ from 9.25 to 18%, when the two cutoff points proposed by the EWGSOP for lean mass, muscle strength and gait speed are selected and combined [8]. Sarcopenia is now a major public health issue. It has been widely associated with negative health outcomes, including but not exhaustively physical disability, falls, injurious falls, nursing home admissions, depression, hospitalizations and mortality [9‐11]. All these consequences are linked to direct healthcare costs. In 2000, these were estimated to raise up to 18.5 billion USD in the USA [8, 12]. Reducing the prevalence of sarcopenia by 10% would result in saving 1.1 billion USD per year in the USA [13]. There is no doubt, because of the current burden of sarcopenia but also because the number of older people is increasing all over the world that health policy decision-makers will soon consider financial investment in sarcopenia prevention and treatment to ensure important future savings [14]. However, to convince health authorities of the emergency to invest in the sarcopenia field, it is of critical importance to produce reliable figures of the expected burden of sarcopenia in the coming years. Therefore, we projected the potential future prevalence of sarcopenia in Europe for the next 30 years. We used age and gender-specific European population projections, and the various diagnostic cutoff points proposed by the EWGSOP, for lean mass, muscle strength and gait speed [6, 8].

The EU28 population is expected to raise from 509,164,624 individuals in 2016 to 525,171,079 individuals in 2045 (a 3.1% increase). The proportion of women above the age of 65 years should increase from 21.1% in 2016 (54,942,878 women) to 30.0% in 2045 (80,105,255 women), i.e., a 31.4% increase The proportion of men in this age group should increase from 16.5% in 2016 (41,004,959 men) to 25.2% in 2045 (65,050,660 men), i.e., a 37.0% increase.

Using the definition providing the lowest prevalence estimates, the number of individuals with sarcopenia would rise in Europe from 10,869,527 in 2016 to 18,735,173 in 2045 (a 72.4% increase). This corresponds to an overall prevalence of sarcopenia in the elderly rising from 11.1% in 2016 to 12.9% in 2045 (Fig. 3).

With the definition providing the highest prevalence estimates, the number of individuals with sarcopenia would rise from 19,740,527 in 2016 to 32,338,990 in 2045 (a 63.8% increase), corresponding to overall prevalence rates in the elderly of 20.2 and 22.3% for 2016 and 2045, respectively (Fig. 3).

Women would account for 44.2–41.9% of prevalent cases in 2016–2045 with the lowest estimates but for 66.4–64.0% of prevalent cases in 2016–2045 with the highest estimates, respectively (Fig. 4).

Our results suggest that, during the next 30 years, the prevalence of sarcopenia will significantly increase, independently of the chosen definition of the condition. This increase in prevalence corresponds to a number of sarcopenic individuals varying between 18 million and 32 million, within the EU28 countries, as a function of the selected diagnostic thresholds, for muscle mass, muscle strength and gait speed.

Several factors may affect the observed prevalence of a chronic disorder. Sarcopenia being an age-related disorder, its prevalence will be influenced by the longevity of the population. Recent probabilistic projections suggest that, in the next decades, whereas the rate of increase in life expectancy will decline, gains will continue asymptomatically, at a linear rate on average [16]. Therefore, our assumption of an increase in life expectancy in both genders, between now and 2045, based on the last updated main scenario projection available for the EU seems realistic. An increased mortality rate may also negatively impact the prevalence of a chronic disorder. Whereas it is well accepted that sarcopenia is directly linked to frailty [17], and subsequently to at least a twofold increase in overall mortality compared to age-matched subjects [18], the recent recognition of sarcopenia as an independent disease [2] will most likely contribute to an earlier diagnosis and to a more dedicated care, all factors contributing to a longer life of sarcopenic patients. The attention focused on sarcopenia will also induce research and development toward an improvement of the currently available diagnostic tools [19], allowing for a wide availability of more accurate and affordable equipments, another factor that might significantly contribute to an increase in the observed prevalence of the disease, hence suggesting that our projection rates remain highly conservative. The progressive switch between bioimpedance and dual-X ray absorptiometry (DXA) for the measurement of appendicular lean mass (ALM) was indeed followed by the detection of a greater number of sarcopenic cases [20]. However, preventative measures, including nutritional optimization, food supplements or regular resistance-training physical exercise become widely recommended in elderly subjects and may improve musculoskeletal heath, reduce or delay the development of muscle wasting and subsequent sarcopenia [21‐24], hence decreasing its prevalence in the coming years. Whereas several potential promising pharmacological interventions are under development to improve physical performance in elderly subjects with frailty or sarcopenia [25‐27] the likelihood that these interventions will fully revert the process of loss of muscle mass, strength or performance is very low, which means that even if widely available in a soon future, these therapeutic option will not impact on the prevalence of the disease.

The figures presented in this study may be challenged because we based over assumptions on one single definition of sarcopenia, even widely accepted, i.e., the EWGSOP 2010 consensus [6]. Selecting other definitions would most likely result in different absolute numbers of projected patients [7]. Similarly, the prevalence of sarcopenia for the various thresholds of skeletal muscle mass, muscle strength and physical performance were also derived from one single study [8] and using other sources might lead to the selection of different values of baseline prevalence. However, these changes in crude figures and raw numbers of current or projected patients would not modify the global trend of our study suggesting a real twenty-first century “epidemics” of sarcopenia and frailty if appropriate attention is not promptly brought to this issue.

A potentially important issue, which might be faced in the coming years, if DXA remains the gold standard for the assessment of ALM is the impact of the growing number of obese individuals [28] on the observed prevalence of sarcopenia. Precision and accuracy of DXA for the assessment of ALM is significantly lowered in obese individuals compared to people with normal weight [29]. Increased fat mass may indeed blunt the identification of low ALM and somehow “mask” sarcopenia, which may in turn artifactually decrease the number of properly identified sarcopenic subjects.

In conclusion, by using a projection model based on the current prevalence of sarcopenia and demographic data available for the population of 28 countries of EU, we suggest that the number of sarcopenic patients will dramatically increase in the next 30 years, making consequences of muscle wasting a major public health issue. These figures can be used as a basis to motivate heath policy makers and health providers to consider muscle health as a first healthcare priority in the soon future.