Sarcopenia Definition and Outcomes Consortium 2020 Definition: Association and Discriminatory Accuracy of Sarcopenia With Disability in the Canadian Longitudinal Study on Aging.

Background: Previous sarcopenia definitions have poor discriminatory accuracy for identifying people with/without relevant health outcomes, and poor agreement between methods of operationalizing sarcopenia criterion. The 2020 Sarcopenia Definitions and Outcomes Consortium (SDOC) definition recommends grip strength (absolute, or standardized to body mass index, total body fat, lean arm mass, or weight), and gait speed. The agreement between methods of operationalizing grip strength and discriminatory accuracy of the SDOC definition for health outcomes such as activities of daily living (ADL) disability is unknown.

Methods: Cross-sectional analyses of 27 924 Canadian Longitudinal Study on Aging participants aged 45-85 at baseline (2012-2015) stratified by sex. The associations of the SDOC definitions with ADL disability were assessed using logistic regression. Area under the curve (AUC) analyses were conducted to assess discriminatory accuracy. Agreement between methods of operationalizing grip strength was measured using Cohen's kappa.

Results: Sarcopenia was associated with 1.60 (1.42-1.80) to 5.80 (4.89-6.88) greater odds of ADL disability with AUC values between 0.60 and 0.81. Agreement between methods of operationalizing grip strength was between 0.10-0.80 for grip strength alone and 0.45-0.91 when combined with gait speed.

Conclusions: The SDOC-suggested criteria of grip strength and gait speed are significantly associated with ADL disability and have high discriminatory accuracy. However, the agreement between methods of operationalizing grip strength tended to be modest, and AUC, sensitivity, and specificity differed depending on the definition. We suggest a single measure of grip strength be considered and age-stratified cutoff values to improve AUC values.