The Conceptual Definition of Sarcopenia: Delphi Consensus from the Global Leadership Initiative in Sarcopenia (GLIS)

The Conceptual Definition of Sarcopenia: Delphi Consensus from the Global Leadership Initiative in Sarcopenia (GLIS) Ben Kirk Peggy M. Cawthon Hidenori Arai José Alberto Ávila‐Funes Rocco Barazzoni Shalender Bhasin Ellen F. Binder Olivier Bruyère Tommy Cederholm Liang‐Kung Chen Cyrus Cooper Gustavo Duque Roger A. Fielding Jack M. Guralnik Douglas P. Kiel Francesco Landi Jean‐Yves Reginster Avan Aihie Sayer Marjolein Visser Stephan von Haehling Jean Woo Alfonso J. Cruz‐Jentoft The Global Leadership Initiative in Sarcopenia (GLIS) group Alberto Frisoli Júnior Andrea B. Maier Anne B. Newman Anton De Spiegeleer Antoneta Granic Antonio Cherubini Assim M. AlAbdulKader Charlotte Beaudart Brian C. Clark Todd T. Brown Carla M. Prado Carolyn Greig Chang Won Won Charlotte Suetta Chih‐Kuang Liang Christopher Hurst Daniel Rooks David G. Le Couteur David Scott Debra L. Waters Dolores Sánchez‐Rodríguez Esmee M. Reijnierse Eva Topinková Fanny Petermann‐Rocha Finbarr C. Martin Gülistan Bahat Haya F. Alhmly Iván Aprahamian Jae‐Young Lim Jean‐Pierre Michel Jesse Zanker John A. Batsis John А. Kanis Joshua R. Lewis Juergen Bauer Julie A. Pasco Justin Keogh Kaisu Pitkälä Ken Madden Kenji Toba Kristina Norman L. Schaap Lin Kang Li‐Ning Peng Lisa K. Micklesfield C.P.G.M. de Groot Lorenzo M. Donini Marc Sim Marı́a Cristina González Marie-Josiane Ntsama Essomba Masafumi Kuzuya Mathis Grossmann Matteo Cesari Michael Tieland Miles D. Witham Ming-Yueh Chou Minoru Yamada Miranda D. Grounds Pedro Abizanda Soler Qian‐Li Xue Rachel Cooper Rainer Wirth Renuka Visvanathan Reshma Aziz Merchant René Rizzoli Robin M. Daly Sebastiana Kalula Siân Robinson Stany Perkisas S. Schneider Steven B. Heymsfield Steven Phu Stuart M. Phillips Sun Young Kim Suzette L. Pereira Thomas E. Gill Tomasz Grodzicki Tomasz Kostka Tung‐Wai Auyeung Wee Shiong Lim Wei‐Ju Lee Yasmin Algindan Yosuke Yamada Yunhwan Lee Yves Boirie‌ Yvette C. Luiking

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The Conceptual Definition of Sarcopenia: Delphi Consensus from the Global Leadership Initiative in Sarcopenia (GLIS) 2024 Age and Ageing 10.1093/ageing/afae052 kirk2024-the-conceptual-definition-of-sarco kirk2024-the-conceptual-definition-of-sarco.txt, the project's staged copy fac32e2ca9d64103b04a078ada4f8ce9907f9b2d cc-by-nc medicine

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0 spans located by searching the stored text for the quote's exact words, allowing any whitespace between them A DEFINITION DECIDED BY VOTE, WITH EVERY VOTE PUBLISHED - 107 experts from 29 countries ranking statements about what sarcopenia IS, under a pre-specified agreement threshold, to harmonise six competing definitions into one Quotation withheld because this record is not cleared for redistribution. which elements belong in the CONCEPT of sarcopenia, decided before and separately from how any of them would be measured Quotation withheld because this record is not cleared for redistribution. the first global CONCEPTUAL definition of sarcopenia - reduced muscle mass and muscle strength, plus muscle-specific strength, with physical performance placed outside the definition as an outcome and severity excluded entirely Quotation withheld because this record is not cleared for redistribution. method Quotation withheld because this record is not cleared for redistribution. a construct whose membership is settled by percentage agreement among named experts, and whose boundary therefore sits at a threshold somebody chose Quotation withheld because this record is not cleared for redistribution. expert-consensus expert-consensus Quotation withheld because this record is not cleared for redistribution. THE ELEMENT THAT MOVED FROM BEING PART OF THE THING TO BEING CAUSED BY IT: `impaired physical performance was accepted as an `OUTCOME` (Sarcopenia increases the risk of impaired physical performance (97.9%)) rather than a `COMPONENT` of sarcopenia (Physical performance should be part of the conceptual definition of sarcopenia (79.4%))`. In EWGSOP 2010 - paper 64 in this corpus - LOW PHYSICAL PERFORMANCE IS CRITERION 3, a diagnostic component. Fourteen years later the same element is a consequence. One relation, two of this corpus's edge types, and the vote that moved it is printed to one decimal place Quotation withheld because this record is not cleared for redistribution. AND THE THRESHOLD IS PRE-SPECIFIED, SO THE BOUNDARY OF THE CONCEPT IS A NUMBER SOMEBODY CHOSE: `low agreement (<70% respondents scoring >=7), moderate agreement (70 to 80%) or strong agreement (>80%). Statements with strong agreement were accepted, and statements with low agreement were REJECTED. Statements with moderate agreement were REINTRODUCED in the subsequent round until consensus was reached.` Muscle-specific strength entered at 80.8%; physical performance was excluded at 79.8%. ONE PERCENTAGE POINT OF A 107-PERSON SURVEY DECIDES WHAT THE DISEASE IS Quotation withheld because this record is not cleared for redistribution. AND THE PAPER SAYS THE MARGIN OUT LOUD: `The overall support for inclusion of specific strength ... was only slightly higher than our threshold for agreement - 80.8% supported its inclusion when the threshold is 80%, and this statement did not meet the threshold in the first round.` A component of the definition admitted by eight tenths of a point, on a second attempt, and the authors flag it as something the operational phase may undo Quotation withheld because this record is not cleared for redistribution. AND ONE STATEMENT WAS REJECTED BECAUSE A DIFFERENT ONE FAILED: `Statement 5 `The conceptual definition of sarcopenia should include LEVELS OF SEVERITY` was rejected with an agreement of 77.0% ... AS STATEMENT 5 did not meet the acceptance threshold (>80%), THE REMAINING FOUR STATEMENTS RELATING TO `MARKERS OF THE SEVERITY OF SARCOPENIA` were rejected.` The vote that removed them is not a vote about them Quotation withheld because this record is not cleared for redistribution. AND ONE OF THE FOUR HAD PASSED: `Physical performance should be A MARKER OF SEVERITY for the conceptual definition of sarcopenia. AGREEMENT: 81.9% (mean score: 7.6 +/- 2.4; answered = 93, skipped = 14).` Above the 80% threshold, and rejected anyway, because the statement it depended on scored 77.0%. A dependency between statements that the threshold rule does not model Quotation withheld because this record is not cleared for redistribution. AND THE INSTRUMENT WAS DELIBERATELY REMOVED FROM THE QUESTION: `Quotation withheld` A consensus body explicitly preventing the apparatus from shaping the concept - the inverse of leslie2022, where a construct is bounded by a filter pore. And they knew it had been happening Quotation withheld because this record is not cleared for redistribution. BECAUSE THE EARLIER DISAGREEMENTS WERE PARTLY ABOUT INSTRUMENTS AND PARTLY ABOUT WORDS: `some of the differences in previous definitions were related to disagreements on whether muscle mass should be included in the definition partly due to measurement issues of available techniques ..., whether physical function should be considered as part of the definition or as an outcome, and around the concept of muscle quality. In addition, some terms were not well defined in the literature ... the term `SARCOPENIA` had been used to refer to low muscle mass alone in some studies. For this reason, the first product of the GLIS initiative was A GLOSSARY OF TERMS.` A working group whose first output is a vocabulary, because the vocabulary was the obstacle Quotation withheld because this record is not cleared for redistribution. AND THE 2010 ADMINISTRATIVE GAP IS HALF CLOSED, IN THE OTHER ORDER: `Sarcopenia also lacks a global and widely accepted definition that can be routinely used in clinical settings, even though an ICD10-CM code for this condition exists.` cruz-jentoft2010 listed the missing ICD-9 code beside the missing definition. THE CODE ARRIVED FIRST - in one national modification, not in the classification itself Quotation withheld because this record is not cleared for redistribution. AND THE STANDARDS BODY TOLD THEM WHAT WOULD CLOSE THE REST: `The WHO was also contacted, and we were informed that a global definition would facilitate inclusion of sarcopenia in the International Classification of Diseases (at present it is only included in the Clinical Modification version of ICD).` The definition is being written partly IN ORDER TO obtain a code - the vocabulary and its administrative slot pulling on each other, stated by both parties Quotation withheld because this record is not cleared for redistribution. THE REASON TO AGREE ON A WORD IS ADMINISTRATIVE RECOGNITION: `the World Health Organization (WHO) has yet to include an ICD-10 code for sarcopenia ... A GLOBAL DEFINITION of sarcopenia would ease the adoption of an ICD-10 CODE by WHO, which, in turn, would increase clinical recognition of this condition worldwide.` The chain runs definition -> code -> recognition, and the paper states it in that order. Quotation withheld because this record is not cleared for redistribution. AND CONCEPTUAL AGREEMENT IS SEQUENCED BEFORE OPERATIONAL AGREEMENT, DELIBERATELY: `Quotation withheld.` Every other chain in this corpus revises criteria and thresholds together; this one splits meaning from measurement and does meaning first. Quotation withheld because this record is not cleared for redistribution. SIX DEFINITIONS AND THE REPAIR IS A SEVENTH BODY: `Several groups have proposed definitions of sarcopenia, including the AWGS, the ANZSSFR, the EWGSOP that issued guidelines in 2010 that were REVISED IN 2019; the FNIH Sarcopenia Project, the IWGS and the SDOC`. The response to six competing committees is to convene a global one - the same move ISAPP made for `prebiotic` after five definitions. Quotation withheld because this record is not cleared for redistribution. THE ACCEPTED COMPONENTS OVERLAP AND THE PAPER SAYS SO: `Quotation withheld` Muscle-specific strength is strength standardised to size, so voting all three in may have voted the same two in twice - a defect in the definition discovered after the vote that produced it Quotation withheld because this record is not cleared for redistribution. AND THE PROXY THE OPERATIONAL DEFINITION WILL HAVE TO USE IS DISPUTED: `the SDOC found that Quotation withheld, and its associations with sarcopenia-related outcomes (mortality, fractures, falls, disability) are weak or inconsistent.` The concept was defined with the instrument assumed perfect; the instrument is neither perfect nor agreed Quotation withheld because this record is not cleared for redistribution. and the conceptual definition is explicitly NOT usable yet: `The next phase of GLIS will include the OPERATIONALIZATION of the newly developed conceptual definition` - so the paper defines the condition and defers every cut-off point, which is the exact reverse of cruz-jentoft2010, whose Table 5 is nothing but cut-off points Quotation withheld because this record is not cleared for redistribution. and a 52% response rate with a European majority: `The GLIS included reasonable representation of men and women, and geography, although most of the respondents were from Europe. The total response rate of GLIS was 52% ... which could have been higher. Nevertheless, we retained 100% (107/107) of participants through both rounds`. Both conceded in the strengths paragraph Quotation withheld because this record is not cleared for redistribution. instructing the experts to ASSUME PERFECT, FEASIBLE ASSESSMENTS of each listed measure existed eliminates: answers skewed by which measurements happen to be accurate or available - the apparatus deciding the concept · outcome: held Quotation withheld because this record is not cleared for redistribution. pre-specifying the agreement thresholds (<70% / 70-80% / >80%) before the survey ran eliminates: a threshold chosen after the votes were seen · outcome: held Quotation withheld because this record is not cleared for redistribution. a glossary of sarcopenia terms published BEFORE the Delphi statements were voted on eliminates: experts agreeing on a statement while meaning different things by its words - 'many different definitions of muscle quality were used in previous studies' · outcome: partial Quotation withheld because this record is not cleared for redistribution. sarcopenia sarcopenia Quotation withheld because this record is not cleared for redistribution. impaired physical performance impaired physical performance Quotation withheld because this record is not cleared for redistribution. muscle-specific strength muscle-specific strength Quotation withheld because this record is not cleared for redistribution. muscle mass muscle mass Quotation withheld because this record is not cleared for redistribution. lean mass lean mass Quotation withheld because this record is not cleared for redistribution. Delphi Delphi Quotation withheld because this record is not cleared for redistribution. gold standard gold standard Quotation withheld because this record is not cleared for redistribution. conceptual definition conceptual definition Quotation withheld because this record is not cleared for redistribution. `sarcopenia` (GLIS 2024, CONCEPTUAL) - `the concurrent combination of reduced muscle mass and muscle strength`, plus muscle-specific strength; a generalised disease of skeletal muscle, potentially reversible, the same in clinic and research, and NOT varying by setting, age or condition Quotation withheld because this record is not cleared for redistribution. `physical performance` - IN the 2010 definition as diagnostic criterion 3, OUT of the 2024 one at 79.4%, and readmitted as an OUTCOME at 97.9% Quotation withheld because this record is not cleared for redistribution. `muscle-specific strength` - `strength standardised to muscle size`; admitted to the definition at 80.8% against an 80% threshold, having failed round 1 Quotation withheld because this record is not cleared for redistribution. `conceptual definition` vs `operational definition` - GLIS separates them ON PURPOSE and produces only the first, deferring every measure and cut-off point to a later phase Quotation withheld because this record is not cleared for redistribution. `sarcopenia` - SIX RIVAL DEFINITIONS, EACH WITH AN INSTITUTIONAL OWNER, ENUMERATED IN ONE PARAGRAPH: AWGS, ANZSSFR, EWGSOP (2010, revised 2019), the FNIH Sarcopenia Project, IWGS, and SDOC. Not a term with two senses - a term with six committees. Quotation withheld because this record is not cleared for redistribution. `gold standard` - A THING TO BE BUILT, NOT FOUND: GLIS was formed `in an attempt to harmonise these competing definitions into one unifying common classification that would be used as the gold standard`. In lotvall2014 the gold standard is DENIED to exist; in doyle2019 it is AWARDED to an incumbent; here it is a DELIVERABLE. Quotation withheld because this record is not cleared for redistribution. claim_type: method a second reading reaching the same value. Recorded: method — note: A BLIND second reading by the project on 2026-08-25: the record's own claim type/method/phenomenon were not looked at until every value here was written and substring-verified. Not applied - a person decides. Sampling frame: the 504 staged records carrying no alternatives block, so this never re-measures the 202. All 11 records with 130+ tags were taken as a census and 19 more spread one per discipline across 22 disciplines - the dense non-neuroscience cell is the one the 202 do not contain (inside them, 94-100% of the densest bands are neuroscience; among these 11, one is)., Quotation withheld because this record is not cleared for redistribution. method: delphi-consensus a second reading DIFFERING from the recorded value. Recorded: expert-consensus — note: A BLIND second reading by the project on 2026-08-25: the record's own claim type/method/phenomenon were not looked at until every value here was written and substring-verified. Not applied - a person decides. Sampling frame: the 504 staged records carrying no alternatives block, so this never re-measures the 202. All 11 records with 130+ tags were taken as a census and 19 more spread one per discipline across 22 disciplines - the dense non-neuroscience cell is the one the 202 do not contain (inside them, 94-100% of the densest bands are neuroscience; among these 11, one is)., Quotation withheld because this record is not cleared for redistribution. extends → the six competing regional definitions of sarcopenia - AWGS, ANZSSFR, EWGSOP (2010, revised 2019), FNIH, IWGS and SDOC - which GLIS was formed to harmonise into one classification Quotation withheld because this record is not cleared for redistribution. critiques → EWGSOP 2010's inclusion of physical performance as a diagnostic criterion, which this Delphi rejects as a component at 79.4% and readmits as an outcome at 97.9% Quotation withheld because this record is not cleared for redistribution. sarcopenia —causes→ impaired physical performance sarcopenia impaired physical performance the relation itself is separately evidenced · strength of the relation: 0.95 · note: THE EDGE THAT REPLACED A part-of. EWGSOP 2010 made low physical performance diagnostic CRITERION 3 - part of the condition. GLIS 2024 puts the same element outside the definition and back in as a consequence: `impaired physical performance was accepted as an `OUTCOME` ... rather than a `COMPONENT` of sarcopenia`. The two readings differ by 18.5 percentage points in one survey of 107 people · the relation stated: accepted as an OUTCOME of sarcopenia at 97.9%, having been rejected as a COMPONENT of it at 79.4% in the same survey Quotation withheld because this record is not cleared for redistribution. muscle-specific strength —part-of→ sarcopenia muscle-specific strength sarcopenia the relation itself is separately evidenced · strength of the relation: 0.9 · note: 'WOULD INCLUDE…'. Weight 0.9: the paper's own phrase is 'part of the conceptual DEFINITION of sarcopenia', and this corpus can say that something is part of a THING but not that it is part of a DEFINITION - the same gap cruz-jentoft2010 exposed with 'sarcopenia is one of the elements of the proposed definition for cachexia'. Twice in two records · the relation stated: voted a COMPONENT of the conceptual definition at 80.8%, against a threshold of 80% Quotation withheld because this record is not cleared for redistribution. lean mass —distinct-from→ muscle mass lean mass muscle mass the relation itself is separately evidenced · strength of the relation: 0.95 · note: 'SUBSTANTIAL DISAGREEMENT…' The concept was voted on with the instruments assumed perfect; this is the instrument that will actually be used · the relation stated: lean mass is the available proxy and DOES NOT DIRECTLY MEASURE muscle mass Quotation withheld because this record is not cleared for redistribution. impaired physical performance was accepted as an outcome (97.9%) rather than a component (79.4%) of sarcopenia impaired physical performance was accepted as an outcome (97.9%) rather than a component (79.4%) of sarcopenia Quotation withheld because this record is not cleared for redistribution. pre-specified thresholds: over 80% agreement accepted, 70-80% reintroduced, under 70% rejected pre-specified thresholds: over 80% agreement accepted, 70-80% reintroduced, under 70% rejected Quotation withheld because this record is not cleared for redistribution. because statement 5 missed the 80% threshold (77.0%), the four severity-marker statements were rejected because statement 5 missed the 80% threshold (77.0%), the four severity-marker statements were rejected Quotation withheld because this record is not cleared for redistribution. THE INSTRUMENT WAS DELIBERATELY REMOVED FROM THE QUESTION: `To avoid the issue that answers might be skewed by the accuracy and lack of currently available measurement methods, experts were asked to assume that perfect, feasible assessments of each listed measure existed` THE INSTRUMENT WAS DELIBERATELY REMOVED FROM THE QUESTION: `To avoid the issue that answers might be skewed by the accuracy and lack of currently available measurement methods, experts were asked to assume that perfect, feasible assessments of each listed measure existed` Quotation withheld because this record is not cleared for redistribution. sarcopenia lacks a widely accepted clinical definition even though an ICD-10-CM code exists sarcopenia lacks a widely accepted clinical definition even though an ICD-10-CM code exists Quotation withheld because this record is not cleared for redistribution. AND THE ACCEPTED COMPONENTS MAY COUNT THE SAME THING TWICE: `how to consider these potentially overlapping components, where muscle mass and strength may be the same components included in the specific strength measure` AND THE ACCEPTED COMPONENTS MAY COUNT THE SAME THING TWICE: `how to consider these potentially overlapping components, where muscle mass and strength may be the same components included in the specific strength measure` Quotation withheld because this record is not cleared for redistribution. `the concurrent combination of reduced muscle mass and muscle strength` ... `a generalised disease of skeletal muscle` ... `should not vary by setting of care, age or condition, or use (clinic vs. research)` ... `a potentially reversible disease` sarcopenia Quotation withheld because this record is not cleared for redistribution. `strength standardised to muscle size` - `an attempt to blend measurements of muscle mass and strength in a single component`, admitted at 80.8% muscle-specific strength Quotation withheld because this record is not cleared for redistribution. below the pre-specified 80% threshold, so physical performance is not part of the condition agreement, physical performance as a COMPONENT Quotation withheld because this record is not cleared for redistribution. the same element, the same survey, as a consequence instead of a part agreement, sarcopenia INCREASES THE RISK of impaired physical performance Quotation withheld because this record is not cleared for redistribution. `only slightly higher than our threshold for agreement ... and this statement did not meet the threshold in the first round` agreement, muscle-specific strength as a component Quotation withheld because this record is not cleared for redistribution. `AS STATEMENT 5 did not meet the acceptance threshold (>80%), THE REMAINING FOUR (50%) STATEMENTS RELATING TO MARKERS OF THE SEVERITY OF SARCOPENIA WERE REJECTED` agreement, levels of severity in the definition Quotation withheld because this record is not cleared for redistribution. rejected because its parent statement scored 77.0% - the vote that removed it is not a vote about it agreement, physical performance as a MARKER OF SEVERITY value source note: THE VALUE DRAWS ON THE PAPER BEYOND THIS QUOTE: the 80% threshold is set in the methods ('strong agreement (>80%)'), not in this quote, and so is the reason the statement was still rejected. Quotation withheld because this record is not cleared for redistribution. `although most of the respondents were from Europe` Delphi panel Quotation withheld because this record is not cleared for redistribution. the share of respondents scoring 7 or more on an 11-point Likert scale - the statistic that decides membership of the concept percentage agreement Quotation withheld because this record is not cleared for redistribution. accepted into the conceptual definition at 93.1%, the highest of the three components muscle strength Quotation withheld because this record is not cleared for redistribution.

The full text of this article is not redistributable, so it is not included here. The evidence sentences are withheld with it; the tag layer and its grounding status remain. The article itself is at https://doi.org/10.1093/ageing/afae052.