Aspectos psicométricos e biológicos da fragilidade e massa muscular em idosos comunitários: resultados do estudo PRO-EVA

Abstract

Introduction: Frailty is a biological syndrome characterized by an increase in physical and psychological vulnerability and reduced functionality, resistance to stressors, physiological reserves, and intrinsic capacity of an individual. The development of this condition seems to be, in part, associated with the biological mechanisms involved in the process of aging, which makes it essential to recognize the interplay between the biology of aging and the biology of frailty. One of the characteristics of the physical frailty is the reduced muscle mass, which reflects in physical and social consequences. The use of low-cost and easily applicable tools for frailty and low muscle mass (LMM) screening in older adults is feasible in primary health care, since their diagnosis are complex and require the use of high-cost technologies. Aim: To analyze the biological aspects of frailty and LMM, in addition to encouraging the screening of both conditions through psychometric measures. Methods: This thesis comprises a narrative review and two cross-sectional studies composed of 786 (article 1) and 700 (article 2) communitydwelling older adults living in Parnamirim (Rio Grande do Norte), aged 60 years or older. Sociodemographic, anthropometric, body composition and physical performance data were collected. The diagnostic accuracy of the Short Physical Performance Battery (SPPB) for the screening of pre-frailty and frailty was performed. Classification and Regression Tree (CaRT) analyses were performed to identify an algorithm for the screening of LMM. In relation to the narrative review, information on the associations between the hallmarks of aging proposed by López-Otín et al. (2013) and frailty were gathered. Results: Article 1: The cut-off points identified for the total SPPB score, walking time, and chair stand time were 9 points or less (accuracy of 72.6%), 5 seconds or less, and 13 seconds or less, respectively, for frailty screening and 11 points or less (accuracy of 58.7%), 4 seconds or less, and 10 seconds or less, respectively, for prefrailty screening. Article 2: An algorithm with high accuracy, based on the factors of BMI (values ≤ 22.7 kg/m² for men and ≤ 24.9 kg/m² for women), sex (female) and calf circumference (values ≤ 31.7 cm for women with a BMI ≤ 24.9 kg/m²). Article 3: The main putative biomarkers of aging associated with frailty were: mitochondrial DNA copy number, telomere length, global DNA methylation, Hsp70, Hsp72, IGF-1, SIRT1, GDF-15, CD4+ and CD8+ cell percentages, circulating osteogenic progenitor (COP) cells, and IL-6, CRP and TNF-alpha. Conclusions: The identification of frailty is possible through the SPPB, since it has good accuracy to discriminate between non-frail and frail older adults using a cut-off point of 9 or less in the total score, being better to identify the true negatives (older adults who are not frail). The developed algorithm in the present study had high accuracy, sensitivity and specificity for LMM screening in older adults based on the factors of BMI, sex and calf circumference. In addition, the algorithm was associated with the strength and function. Finally, among the main biomarkers of aging associated with frailty, IGF-1, SIRT1, GDF-15, IL-6, CRP and TNF-alpha presented more evidence, highlighting the importance of inflammation and nutrient sensing on frailty.