M.L. Sáez de Asteasu1, E.L. Cadore2, T. Steffens2, E. Blanco-Rambo2, T.C. Schneider2, M. Izquierdo1, C. Pietta-Dias2
1. Navarrabiomed, Hospital Universitario de Navarra (HUN), Universidad Pública de Navarra (UPNA), IdiSNA, Pamplona, Spain; 2. Exercise Research Laboratory, School of Physical Education, Physiotherapy and Dance, Universidade Federal do Rio Grande do Sul, Brazil
Corresponding Author: Mikel L. Sáez de Asteasu, Department of Health Sciences, Public University of Navarre, Avenida Irunlarrea s/n, Pamplona, Navarre, Spain, e-mail: mikel.lopez.saezdeasteasu@gmail.com
J Frailty Aging 2023;in press
Published online April 6, 2023, http://dx.doi.org/10.14283/jfa.2023.21
Abstract
The aim of the present study was to investigate the association between handgrip strength and mortality in Brazilian frail nonagenarians and centenarians. Eighty-one oldest old were included (mean age [SD]: 94.2 [3.8] years). Data on strength was assessed by handgrip strength. Mortality rate of the participants was evaluated at 1-year follow-up after the functional assessment. A logistic regression analysis was used to assess differences in categories of handgrip strength between groups regarding the mortality rate. Forty-six participants (56.8%) had reduced handgrip strength. After 1 year, there were 16 deaths. Those older adults with a low handgrip strength had higher prevalence (28.3% vs. 8.6%) and increased risk of mortality than those with preserved handgrip strength (Odds ratio=4.4, confidence interval 95% 1.1, 18.4) (p=0.042). Reduced handgrip strength is associated with higher mortality rate at 1-year follow-up in Brazilian frail nonagenarians and centenarians.
Key words: Oldest-old, intrinsic capacity, frailty, muscle strength.
Introduction
Handgrip strength has been suggested as an essential clinical sign of ageing (1-2). As such, it is a simple but powerful predictor of multiple adverse events in different age groups (3-4), including disability, morbidity and mortality in older adults (2, 5). Based on its applicability, handgrip strength has been widely adopted as an exceptional indicator of overall muscle strength (6), and has been included as an essential domain of the sarcopenia framework (7) and frailty in older population definitions (8). However, some issues remain unclear, such as whether the association between handgrip strength and future mortality is generalizable across countries of extensively varying socioeconomic status and ethnicity (i.e., South-American countries) (1). In line with this, the main aim of this study was to examine the association between handgrip strength and future mortality in Brazilian frail nonagenarians and centenarians.
Methods
Study design
The present study is part of a larger Brazilian prospective cohort study. Participants’ recruitment and data collection were performed between May of 2018 and May of 2019. Second assessment including mortality was performed after 1 year of follow-up.
Participants
The study population consisted of older adults aged 90 years or older living in the city of Porto Alegre, in the state of Rio Grande do Sul, Brazil. The participants were selected for accessibility through the State Health Department and the City Health Department as institutions co-participating in this research. The units on family health strategies were authorized to provide the contact details and addresses of the older adults who were 90 years of age or older living within the limits of the territorial coverage of the family health strategy units. First, participants were recruited through phone call, and after prior appointment, the collections took place in their home environment. In the cases that there was only the address information, without containing the participants’ phone number for prior contact, the Health Agent accompanied the researcher during the home visit. Furthermore, long-term care facilities for older adults were contacted and public announcements were made to recruit the study population. The inclusion criteria were: older adults living within the limits of the territorial coverage of the family health strategy units, aged 90 years or older with cognitive capacity established by a score of 19 points or more on the Mini Mental State Examination, and who were physically able to perform the functional performance tests and had the ability to walk alone or with a cane/walker. Additionally, all the participants met Fried’s criteria for frailty, which was determined by the presence of three or more of the following domains: slowness, weakness, weight loss, exhaustion, and low physical activity (8). Those participants who had functional incapacity to walk, who used a wheelchair, those who had Parkinson’s disease and lower or upper limb amputation were excluded.
Study endpoints
Muscle function
Handgrip strength was assessed using a Saehan SH 5001 hydraulic hand dynamometer. The participants squeezed gradually and continuously for at least 2–3 seconds, performing the test with the right and left hand in turn for three times. The maximum score in kg for each hand was recorded, and the mean score of left and right hand was used in the analyses. Moreover, participants were categorized according to the European Working Group on Sarcopenia in Older People (EWGSOP) sarcopenia definition regarding the handgrip strength (7). Considering the EWGSOP sarcopenia cut-off points for low muscle strength, those men with a handgrip score lower than 27 kg and women with a score lower than 16 kg were considered to have reduced handgrip strength.
Mortality
Mortality rate of the participants was evaluated at 1-year follow-up after the functional assessment.
Covariates included in the analysis
Demographic and clinical data including body weight, cancer prevalence and comorbidities (i.e., number of chronic diseases) were collected through access to medical records when functional evaluation was performed.
Statistical analysis
Descriptive characteristics are provided as means and standard deviations for quantitative variables and percentages for categorical variables. A logistic regression analysis was used to assess differences in categories of handgrip strength between groups based on the EWGSOP handgrip criteria regarding the mortality rate at 1-year follow-up adjusted by body weight, cancer prevalence and number of chronic diseases. Data were analyzed using IBM SPSS (v27.0 SPSS Inc., Chicago, IL) and a p-value <0.05 was considered statistically significant.
Results
Clinical and demographic characteristics of the participants are shown in Table 1. From 122 individuals initially assessed, 81 participants were included in this study. 58 were women (71.6%); mean age (SD) was 94.2 (3.8) years, and all had multiple comorbidities. The mean value of handgrip strength was 17.6 (7.7) kg (25.9 [7.7] kg for males and 14.4 [4.7] kg for females) and 37 (45.7%) participants suffered one or more falls at 1-year follow-up.
Table 1. Demographic, clinical, functional and adverse event data of the participants
Data are presented as mean (standard deviation) unless otherwise indicated; a. These data were collected through access to medical records; b. Participants with cancer diagnosis were treated previously and were not receiving treatment at the moment of the assessment; c. Polypharmacy was defined according to the number of medications prescribed in the medical history; d. Adverse events were recorded at the end of the follow-up period. Number of falls were obtained by phone interview and mortality rate through access to medical records; Abbreviations: FTSST, five times sit to stand test; TUG, timed up and go
Handgrip strength appears to have a major role in the vital trajectory of frail nonagenarians and centenarians. Those older adults with a handgrip strength score below the cut-off points established by the EWGSOP sarcopenia definition regarding handgrip strength (i.e., 27 kg for men and 16 kg for women), had higher prevalence (28.3% vs. 8.6%) and increased risk of mortality compared with those older adults whose muscle strength was preserved (Odds ratio=4.4, confidence interval 95% 1.1, 18.4) (p=0.042).
Discussion
Handgrip strength has been widely proposed as an important clinical biomarker of ageing in the literature (1-2). Our results showed that handgrip strength is associated with mortality in frail Brazilian nonagenarians and centenarians living within the limits of the territorial coverage of the family health strategy units. The findings from this study add to growing evidence that skeletal muscle function is a key component of health and ageing. Thus, skeletal muscle preservation seems to be a cornerstone for the vital trajectory of this study population.
Loss of muscle function, specifically handgrip strength, is unlikely to be the main factor that contributes for the adverse events of ageing, but it appears to be an adequate clinical marker of underlying ageing processes (1). Previous evidence has highlighted the role of skeletal muscle as an endocrine organ that produces and releases myokines and helps to regulate the nervous, endocrine, and immune systems for the maintenance of homeostasis (9), which is progressively altered during the ageing process (10). Therefore, targeting these myogenic myokines could promote to ameliorate age-related sarcopenia (11). Our findings are in line with previous research (12), showing that those older adults with higher levels of muscle strength had lower mortality rate than older adults with muscle weakness. Because the maintenance of muscle strength may be one of the main aims to preserve good health-related quality of life and to prevent or revert frailty and sarcopenia, regular resistance exercise should be prescribed in people of advanced age, such as nonagenarians and centenarians (13-14).
Handgrip strength has been included as a key domain of the sarcopenia framework (7), and previous studies have highlighted its association with future mortality. Nevertheless, there is a gap on the literature regarding this association in countries of extensively varying socioeconomic status and ethnicity (i.e., South-American countries) (1). Our findings reinforce the association between handgrip strength and mortality risk in oldest old, emphasizing the role of muscle strength as an essential biomarker in frail older adults.
The present cohort study has some limitations that should be acknowledge. The small sample size and the short period of follow-up could jeopardize the generalizability of the results of the present study. Although frail nonagenarians and centenarians able to perform physical evaluations are individuals that are not easily assessed, our results are in consonance with recent evidence that investigated the association between handgrip strength and mortality in this population (15).
In summary, reduced handgrip strength is associated with higher mortality rate at 1-year follow-up in Brazilian frail nonagenarians and centenarians. Future longitudinal studies with larger sample size should provide more consistent evidence considering the role of handgrip strength as a predictor of multiple adverse events in old population.
Ethics approval: This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the local University Ethics Committee (CAAE: 79748517.5.0000.5347), as well as the Ethics Committee from the State Health Department (CAAE: 79748517.5.3002.5312) and from the City Health Department (CAAE: 79748517.5.3001.5338).
Standards of reporting: This study was performed in line with the STROBE Guidelines for observational studies.
Consent to participate: Informed consent was obtained from all individual participants or their legal representatives included in the study.
Data availability: The datasets generated during the current study are available from the corresponding author on reasonable request.
Competing interests: Disclosure of potential conflicts of interest: The authors have no conflict of interest in relation to the present scientific paper.
Funding: This work was supported by National Council for Scientific and Technological Development (CNPq, Brazil) and Coordination for the Improvement of Higher Education Personnel (CAPES, Brazil).
ORCID-ID: Mikel L. Sáez de Asteasu: 0000-0002-4111-5045; Eduardo L. Cadore: 0000-0003-4397-9485; Tainara Steffens: 0000-0002-3594-1199; Eduarda Blanco-Rambo: 0000-0002-7345-7832; Thiago Chaves Schneider: 0000-0001-7466-5871; Mikel Izquierdo: 0000-0002-1506-4272; Caroline Pietta-Dias: 0000-0002-3883-4938.
Contribution statements: All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Mikel L. Sáez de Asteasu, Eduarda Blanco-Rambo and Caroline Pietta-Dias. The first draft of the manuscript was written by Mikel L. Sáez de Asteasu and Eduardo Lusa Cadore. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
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