Functional capacity and risk of falls in the elderly with metabolic syndrome

Introdução: A síndrome metabólica (SM) é a anormalidade metabólica mais comum na população que predispõe a eventos cardiovasculares e pode estar relacionada à baixa aptidão física e baixa capacidade funcional em idosos. O objetivo deste estudo foi avaliar a interferência das alterações metabólicas na capacidade funcional e no risco de quedas em idosos. Métodos: Trata-se de um estudo transversal realizado com 126 idosos, sendo 58 com síndrome metabólica e 68 sem síndrome metabólica, segundo os critérios da International Diabetes Federation. Os índices de Katz, Tinetti, Timed Up e Go e Berg Scale foram aplicados para avaliar a capacidade funcional. A Escala de Eficácia das Quedas-Escala Internacional (FES-I-Brasil) foi utilizada para avaliar o medo de cair. Para análise estatística, foram utilizados os testes de correlação de Mann-Whitney, Qui-quadrado e Spearman. Resultados: Houve associação dos grupos MetS e non-MetS em relação com os estratos de risco do índice TUG [p=0,02; OR=0,38; IC95% (0,16-0,91)]. Entre esses dois grupos, houve diferença significativa na média dos seguintes marcadores: escala de Berg (p=0,03); TUG (p=0,03); FES-I-Brazil (p=0,02). O índice de Kats e IPAQ não apresentaram associação significativa. Conclusões: Os idosos com SM apresentaram maior risco e medo de quedas quando comparados aos pacientes sem SM. No entanto, não houve variação na capacidade de caminhar ou no equilíbrio. Resumo


INTRODUCTION
The biological changes during aging favor the evolution of MetS, which is closely related to the advanced age group. 4 At the same time, the aging process is directly associated with a high prevalence of disability favoring the condition of dependence to perform daily activities, which can generate reduction in physical performance and motor skills. These changes in functional capacity predispose to the risk of falls, increase dependence and the appearance of fear in relation to new falls, causing a restriction of their routine activities, with a decrease in their functional mobility and consequent social isolation. 5 Due to these issues, it is theorized that the presence of MetS in the elderly population is a factor that, due to its own social and pathophysiological characteristics, potentiates the deterioration of functional capacity, promoting greater risk and fear of falls. Based on this theoretical framework, this study aims to evaluate the hypothesis that elderly with MetS have a higher risk of falls than elderly without MetS in Viçosa/MG.
Thus, the study is justified by its practical and social applications. It proves important for proposing the verification of a potential risk factor for the local elderly population, besides contributing significantly to the scientific community. Moreover, there are few reports in the literature on the subject, besides characterizing a pioneer study in the region of Viçosa/MG, being essential to incite new research and open new questions, especially for primary care.

Sample
The population in study consists of elderly people from the region of Viçosa/MG (Brazil), who define people over 60 years of age. It is estimated that in this region there are 80 thousand inhabitants, where 10% consists in the elderly population, leading a population of approximately 8 thousand elderly people.
A priori, the authors estimated a minimum sample of 117 patients, with a 95% confidence interval and 9% margin of error. Elderly people with cognitive deficits, wheelchair users, bedridden, unable to perform the specific tasks of the questionnaires, and who did not sign the free and informed consent term were excluded.

Ethics statement
The study protocol was approved by the Committee for Ethics in Research of the Federal University of Viçosa (CAAE 81072717.3.0000.5153). All subjects signed legal consent forms. Information on demographic characteristics, lifestyle habits and perceived stress level was also assessed. All the individual and nonidentifiable data of the participants that support the results of this article are available from the moment of publication, indefinitely, for any person and purpose. 6

Data Collection
Data were collected, between December 2018 and February 2019, by researchers who were previously trained and divided in a specific way for each questionnaire or test. Each evaluation instrument were applied by two researchers, who had previous training and practiced the application of the tests hours before starting the first day of collection.
All patients who chose to participate in the study voluntarily contributed to the requested physical

Measures
Initially, a semi-structured instrument was applied to investigate the following variables: gender, age, marital status, drug use, previous pathologies, blood pressure and waist circumference. Subsequently, the elderly were divided into two groups: MetS carriers and non-carriers. To determine the presence of MetS, the elderly were classified using the diagnostic criteria proposed by International Diabetes Federation (IDF). 7 The volunteers with MetS presented abdominal circumference above 80cm for women and 90cm for men, associated with two of the following factors: systemic arterial hypertension (SAH) or blood pressure ≥ 130x85mmHg; DM2 or glycemia ≥ 100mg/dL; high triglycerides (≥ 150mg/dL) and low HDL (< 40mg/dL men and < 50mg/dL women). Volunteers with DM2 and SAH, associated with waist circumference above the reference used, were automatically classified as having MetS. All patients were instructed to perform blood tests to assess lipid and glucose levels. Blood tests performed in the six months prior to data collection were used, without the need for a new examination.
To evaluate blood pressure, an aneroid sphygmomanometer was used, with an adult standard Velcro cuff from the Premium ® brand, manufactured in July 2016 (Wenzhou Kangju Medical Instruments Co. Ltd.), duly calibrated. The volunteers were instructed on the need of having an empty bladder and not having used alcohol, tobacco or performed physical activity. The assessment was performed once after the volunteer maintained the sitting position, for five minutes.
In the evaluation of the abdominal circumference, the umbilical scar was used as reference and the measurement was made at the end of the respiratory expiratory movement, with the volunteer in the orthostatic position. To measure the waist circumference, we used fiberglass metric tapes graduated in millimeters with 1.5 meters of the Worker brand. 8

International Physical Activity Questionnaire (IPAQ)
To assess the level of physical activity we used the International Physical Activity Questionnaire

Katz Index and Tinetti Scale
The Katz Index evaluates the independence standard for performing daily life activities and the Tinetti Scale is used to evaluate balance and gait. The Katz Index is a functional evaluation instrument that allows assigning different degrees of functional independence to the elderly according to a final score. The elderly will be classified from A to G, where A and B are classified as functional; C, D and E as intermediate functionality; F and G as less functional. 11 The Tinetti Scale uses sixteen items that evaluate balance and gait generating a total score that determines fall risks. The score ranges from 0 to 28, the higher the score the lower the risk of falls. The classification in relation to the scores is: 0 -19 = high risk of falls, 19 -24 = moderate risk of falls, and 25 -28 = low risk of falls. 12

Berg Scale
To analyze the risk of falls, the Berg scale validated and adapted to the Brazilian culture was used. 13 The Berg scale is used to evaluate elderly and patients with balance deficit, regardless of age, being an evaluation with simple materials (ruler, measuring tape, bench and stopwatch) that lasts approximately 15 minutes. The score ranges from 0 to 56 points: 1 -36 = high risk of falls, 37 -44 = safe locomotion with recommendation of device to aid walking, and 45 -56 = no risk of falls, safe locomotion. 13

Falls Efficacy Scale-International (FES-I-Brazil)
The validated and culturally adapted Falls Efficacy Scale-International scale was applied to assess the fear of falling (FES-I-Brazil). 14 This scale presents questions about the concern with the possibility of falling in relation to 16 activities, with respective scores of one to four, being 1 point for no concern about the decrease in relation to one of the activities, 2 points for a little worried, 3 points for very worried and 4 for extremely worried. The total score can range from 16 (no concern) to 64 (extreme worry). The classification of the elderly in relation to the questionnaire will be according to the total score: 16 points without concern; up to 32 mild concern; up to 48 moderate concern and up to 64 extreme concern.

Statistical analysis
The minimum size of the sample was defined using the coefficient of variation obtained for FES-I-Brazil (27.9%) in this study, considering ten percent of variation around the average, with a minimum number of thirty-five individuals each group. It was possible to verify statistical differences with a 5% level of significance. 15 The data obtained in this research were tabulated in the program Statistical Package for the Social

RESULTS
The sample comprised 126 elderly people who regularly perform the activities proposed by the municipal program for the elderly, 58 of which (46%) were classified as having MetS. The mean age in the MetS group was similar to the non-MetS group (69 ± 6 vs 69 ± 7, respectively). There was a higher prevalence of females in both the MetS group and the non-MetS group and the majority aged 60-69 years (Table 1).
In general, in both groups, the participants were independent when evaluated by the Katz Index,
In the MetS group, there was a statistically moderate negative correlation between Age and Berg (r=-  The presence of a higher risk of falls in elderly patients with MetS corroborates some aspects already described in the literature. Barr points out that in elderly patients, the presence of peripheral neuropathy and radiculopathies can be evident even under conditions of good glycemic control, especially in sedentary and obesity conditions. 16 The presence of peripheral neuropathy, especially in the lower limbs, presents a potential relation with proprioception impairment, influencing significantly the risk of falls. 16,17 In addition, other risk factors that are commonly related to MetS in the elderly are presented as aggravating factors for the risk of falls, such as: sedentary behavior, physical conditions and presence of morbidities. 18 It is already well established that the risk of falling in the elderly population is related to several risk factors, many of which are a natural consequence of the aging process itself. Physiologically, the musculoskeletal function presents significant atrophy as the age advances. The loss of muscle strength in the lower limbs shows progressively over the years and may present a decrease in strength of up to 40% at 70 years when compared to 20 years of age. When considering the association with MetS, the risk of falls is enhanced by the association of neuropathy and muscle weakness, with a sensory dysfunction added to motor impairment. 16 Also reported in the literature is the association between dysfunction in glucose metabolism and vestibular dysfunction in the elderly, generating gait and balance disturbance and predisposing to the risk of falls. Bittar et al. 19 point out that a significant portion of the population presenting dizziness has complications such as DM2 and MetS, and that there is a significant correlation with vestibular problems and dysfunction of glucose metabolism. Dizziness and vertigo in the elderly population are usually associated with vestibular dysfunction or adverse drug effects, directly affecting patient gait and balance. Since it affects gait and balance, there is a significant association between dizziness and an increased risk of falls in this population.
Although this association exists, the sample studied in this study, despite presenting a high risk of falls, was not associated with gait imbalance or balance in the presence of MetS. This finding, explored by the Tinetti scale, leads us to believe that MetS offers a high risk of falls without significantly affecting vestibular function. 17,18,19 In the present study, the fear of falling, evaluated by the FES-I-Brazil scale, presented a slight correlation with the risk of falls, evaluated by the Berg score and the TUG test. This finding corroborates other studies, which justify the presence of fear of falls in patients due to the risk of recurrent falls. 20

Limitations
The limitations of this study are presented by the characteristics intrinsic to its proposal. As it was a transversal work, prospective questions could not be evaluated. In addition, due to its objectivity, this work was limited in evaluating the abovementioned indexes, without evaluating the sociodemographic characteristics or biochemical values of the population. Finally, other factors that may limit functional capacity and increase the risk of falls in the elderly were not considered, such as: orthopedic, neurological and cardiac impairments, drugs that can interfere with the reproduction of the elderly and factors that facilitate the risk of falls.
The future steps, based on the evidence found in this sample, will be to evaluate other issues that can work together with MetS compromising quality of life, such as: sociodemographic aspects, dietary pattern, knowledge and attitude about the disease and biochemical aspects.

CONCLUSIONS
Elderly patients and patients with MetS presented higher risk and fear of falls when compared to patients without MetS, however, there was no variation in gait ability and balance. Preventive methods in primary care are the best ways to improve the quality of life of this population, especially in the presence of comorbidities such as MetS. This study presents evidence that corroborates the premise that elderly people with MetS have a higher risk of falls and may be a target population for preventive measures.

Highlights
The study demonstrates the importance of assessing and intervening in functional capacity and without risk of falls in elderly people with metabolic syndrome. Functional capacity may suffer a negative influence in the presence of MetS as a comorbidity, increasing the risk and fear of falls in the elderly. Preventive methods in primary care are the best ways to improve the quality of life of this population, especially in the presence of comorbidities such as MetS. This study presents evidence that corroborates the premise that elderly people with MetS have a higher risk of falls and may be a target population for preventive measures.

Key points
The study reinforces that there is a relationship between MetS with functional incapacity and risk of falls in the elderly. Elderly with MetS are at a higher risk of falls than older people without MetS.