Sarcopenia in the Canadian Longitudinal Study on Aging: The impact of diagnostic criteria on the agreement between definitions and the association of sarcopenia with falls

Abstract

Objectives: Sarcopenia is defined using a variety of different muscle variables, muscle mass adjustment techniques and cut offs for each variable. The objectives of this thesis were to assess how operational differences in sarcopenia definitions impact the agreement between definitions and the association between sarcopenia and health outcomes such as falls. Methods: A list of sarcopenia definitions was developed which captured the combinations of muscle variables, muscle mass adjustment techniques, and cut offs used in the literature based on a systematic review conducted for this thesis. These definitions were applied to participants taking part in the Canadian Longitudinal Study on Aging, a national study of participants aged 45 to 85 years at baseline. The agreement between the definitions and the association of each definition with falls was assessed. Findings: Both the combination of muscle variables as well as the different muscle mass adjustment techniques generally had limited agreement. Sarcopenia definitions including muscle mass and muscle strength were associated with falls in males, but none of the sarcopenia definitions were associated with falls in females. Area under the curve analyses revealed that even sarcopenia definitions associated with more than two times the odds of falling in males, had a small impact on identifying fallers with values ≤0.56. Conclusions: The results of this thesis show that the existing range of definitions used to define sarcopenia are not equivalent based on the limited agreement and inconsistent association of sarcopenia with falls. The results also show that sarcopenia may have limitations as clinically useful diagnosis for identifying fallers with area under the curve values for all definitions showing that the identification of fallers based on sarcopenic status was at best, modestly better than chance alone.