Introduction: A muscle mass normalized for height2 (MMI) or for body weight (SMI) below 2SD under the mean for a young population defines sarcopenia. This study aimed at setting the cutoffs and the prevalence of sarcopenia in the French elderly population. Another objective was to compare the results obtained with SMI and MMI.
Methods: Muscle mass was assessed by bioelectrical impedance analysis in 782 healthy adults (< 40 years) to determine skeletal mass index (SMI, muscle mass*100/weight) and muscle mass index (MMI, muscle mass/height2). Prevalence was estimated in 888 middle aged (40-59 years) and 218 seniors (60-78 years). All were healthy people.
Results: For women mean-2SD were 6.2 kg/m2 (MMI) and 26.6% (SMI); for men limits were 8.6 kg/m2 (MMI) and 34.4% (SMI). In middle aged persons a small number of them were identified as sarcopenic. In healthy seniors, 2.8% of women and 3.6% of men were sarcopenic (MMI). The prevalence was 23.6% in women and 12.5% in men with SMI. MMI and SMI identified different sarcopenic populations, leaner subjects for MMI while fatter subjects for SMI.
Conclusion: Cutoff values for the French population were defined. Prevalence of sarcopenia was different from that in the US population.