Sarcopenia: evaluation of different diagnostic criteria and its association with muscle strength and functional capacity

INTRODUCTION: Sarcopenia has been associated with increased morbidity and mortality in older people. However, there is still no consensus about the best diagnostic criteria for it. OBJECTIVE: This study aimed to evaluate different diagnostic criteria of sarcopenia and their relationship with muscle strength and functional capacity. METHODS: A cross-sectional study was carried out in Santa Maria-RS, Brazil. Body composition was measured by dual-energy X-ray absorptiometry (DXA). Physical performance was evaluated by the Timed-get-up-and-go test (TGUG). Muscle strength was measured with a handgrip dynamometer. The proposed criteria of sarcopenia were evaluated as follows: A) appendicular lean mass index (aLM/ht2), cutoffs 5.5 kg/m2, 2SD, 10th percentile, and 20th percentile of young reference; B) a linear regression model was used to adjust appendicular lean mass (aLM) for both height and fat mass, cutoff 20th percentile of elderly. RESULTS: In total, 104 women agreed to participate in the research, 39 young (20 to 40 years) and 65 elderly (over 60 years). The prevalence of sarcopenia varied from 0% to 17.2% according to the diagnostic criteria. Regarding muscle strength, the aLM/ht2 cutoff 10th percentile was the criterion with greater area under the ROC curve. However, there were no criteria with an area under the ROC curve greater than 0.5 when TGUG was the outcome. The reclassification showed that the criterion B reclassified 66.7% with normal grip strength as sarcopenic. CONCLUSION: Of these criteria, aLM/ht2 cutoff 10th percentile had stronger correlation with muscle strength. INTRODUÇÃO: Sarcopenia está associada com aumento da morbidade e mortalidade em pessoas idosas. No entanto, ainda não existe consenso sobre o melhor critério diagnóstico para ela. OBJETIVO: Avaliar os diferentes critérios diagnósticos de sarcopenia e sua relação com a força muscular e capacidade funcional. MÉTODOS: Estudo transversal realizado em Santa Maria-RS, Brasil. A composição corporal foi avaliada através de absorciometria por dupla emissão de raios-x (DXA). A capacidade funcional foi inferida por meio dos testes Timed-get-up-and-go (TGUG) e preensão manual com um dinamômetro. Os critérios de sarcopenia propostos foram: A) índice de massa muscular apendicular (aLM/ht²), pontos de corte de 5,5 kg/m2, dois desvios-padrões (dp), percentil 10 e percentil 20 da amostra jovem de referência; B) modelo de regressão linear utilizando massa muscular apendicular (aLM) ajustado para a