Otimização de ferramentas de baixo custo para triagem e diagnóstico da sarcopenia

Abstract

Diagnosing sarcopenia requires muscle quantity, strength and performance evaluation. Assessing muscle mass is usually the most troublesome criterion. Gold standard methods are frequently expensive or unavailable, and the available low-cost methods have low accuracy. This thesis is based on two different approaches to the matter. One of them is the adaptation of an international sarcopenia screening instrument to be used in the Brazilian population, in order to direct efforts and diagnostic resources to patients at increased risk for the pathology. The second approach involves the development of appendicular muscle mass ultrasound and bioelectrical impedance analysis prediction equations for the South American population. For such, data on 193 community-dwelling elderly from Pelotas (a southern Brazilian city), evaluated in the Body Composition Sub-study of the COMO VAI ? study, was used. This thesis' first objective involved the translation of the SARC-F sarcopenia screening questionnaire, originally in English, into Portuguese. Given the weak screening performance observed, a modified version (SARC-CalF) was developed, which delivered better results. For the second approach, new appendicular muscle mass prediction models, specifically designed for the South American elderly, were developed: two using ultrasound, and two using bioelectrical impedance analysis. Muscle mass estimates were not significantly different from the dual-beam X-ray absorptiometry measurements, adopted as the reference method for both tools. Additionally, the predictions were unbiased and their accuracy was comparable to similar models previously developed for other populations. Thus, if confirmed in other samples, the presented results may represent new alternatives for screening and diagnosing sarcopenia in the South American context.