{'fraction_non_alphanumeric': 0.029043969342476807, 'fraction_numerical': 0.017749092375958047, 'mean_word_length': 4.911301859799714, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Analysis of correlation between instruments for evaluation of postural balance in institutionalized elderly

Older people living in a NHs are characterized by a reduced mobility and a worse balance when compared with communitydwelling elderly.5–7 For this older adults, some activities which are apparently simple (such as walking, sit and stand up from a chair) can become risky and difficult to undertake. Consequently, this contributes to the failure to undertake ADLs, inducing a hypokinetic routine, and a vicious circle, which becomes a factor for falls. About 43% of nursing home residents fall at least once a year.8


Introduction
The United Nations evaluate that the number of people 60 years or older is expected to more than double until 2050. 1 The number of olders living in nursing homes (NHs) is also expected to rise. 2,3 In Brazil, the institutionalized elderly represented 1.5% of the elderly population. 4 Living in these institutions can promote social isolation and a reduction in mental and physical activities.
Older people living in a NHs are characterized by a reduced mobility and a worse balance when compared with communitydwelling elderly. [5][6][7] For this older adults, some activities which are apparently simple (such as walking, sit and stand up from a chair) can become risky and difficult to undertake. Consequently, this contributes to the failure to undertake ADLs, inducing a hypokinetic routine, and a vicious circle, which becomes a factor for falls. About 43% of nursing home residents fall at least once a year. 8 The use of tools to screening the risk of falling is useful in identifying older adults who need intervention to prevent future falls. Karuka et al analyzed the correlation between the Functional Reach Test (FRT), the Berg Balance Scale (BBS), the Timed Up and Go (TUG) and the Performance-Oriented Mobility Assessment of Balance (POMA) in the community-dwelling elderly and concluded that it is reasonable to use these instruments together to obtain a better assessment of the balance of these elderly people. 9 In an another study, Persad et al reviewed a sample of available fall assessment approaches targeted at elderly residents in the community, ranging from simple questionnaires to more functional assessments and concluded that of the tests include in the review, many of the approaches were similarly effective in discriminating fallers from non-fallers and predicting future falls. 10 Tiedemann et al examined the comparative ability and clinical utility of eight mobility tests for predicting multiple falls in older community-dwelling people and conclued that the sit-to-stand test with five repetitions, the alternate-step test and the six-metre-walk test were the best tests based on feasibility and predictive validity. 11 Borowicz et al studied which balance test for older adults generates the most reliable results in terms of fall risk assessmentin nursing home residents. The authors concluded that the TUG and POMA were the most useful screening tests for balance and gait impairment in these patients and that two or more tests should be performed for more precise assessment of the risk of falling. 12 In the studies cited above, only community-dwelling elderly were evaluated, but there is a gap in studies assessing which tests have good agreement to assess the balance in institutionalized older people.
Thus, the objectives of this paper was to analyze the correlation between the tests used to assess the body balance in the elderly living in the nursing homes.

Materials and methods
This was an observational study, with a transversal design. The data were collected between August 2016 and June 2017, in three NHs of Marília, São Paulo, Brazil.
Written informed consent was obtained from all patients before enrollment. The study was approved by the Research Ethics Committee of the Faculty of Philosophy and Sciences (UNESP), Marília, São Paulo, Brazil, and was conducted in accordance with Resolution No. 196/96 of the National Health Council (Protocol 1.779.430).
Of the 192 elderly people living in the three Nursing Home Institutions, 45 were included due the eligibility criteria ( Figure 1).

Inclusion and exclusion criteria in sample
Eligibility criteria: were excluded subjects with neurological or musculoskeletal disorders or pain that interfered with their daily activities, with lower extremity joint replacement, with orthostatic postural hypotension, with abnormal scores on the Mini-Mental State Examination according to the educational level and bedridden elderly. 8 The cognitive status was evaluated by Mini Mental State Examination (MMSE), with the following cutoffs: 20 for illiterates; 25 for schooling level of 1 to 4 years; 26.5 for 5 to 8 years; 28 for 9 to 11 years; and 29 for higher levels of education. 13

Procedures for evaluating postural balance
The balance was evaluated using the follow clinical tests: Berg Balance Scale (BBS), Short Physical Performance Battery (SPPB), Timed up and Go (TUG), gait speed by 10 meter walk test, the distance in the Six-minute walk test and Tinetti test. The BBS was translated, adapted and validated for Brazil. 14 and consists of a battery of 14 tasks common to the ADLs, which quantitatively evaluate the risk of falls, through observation undertaken by the examiner. The SPPB is designed to measure functional status and physical performance, assessing walking speed, standing balance, and sit-tostand performance. The SPPB was translated, adapted and validated for Brazilian Portuguese. 15 Functional mobility was evaluated with the TUG test, 16 that measures the time it takes a subject to stand up from a chair, walk 3 m, turn around, walk 3 m back, and sit down again in the same chair, all at their normal pace. The 6MWT is the distance walked in a period of 6 minutes. This test was initially considered an endurance measure and developed to patients with lung diseases, 17 but more recently has been considered a broader measure of mobility and function. 18,19 The Tinetti balance test (Performance Oriented Mobility Assessment II-POMA II), consist of 16 tasks on the balance and gait scales. The maximum score is 28, with a score above 24 points indicating a low risk of falls, a score between 19 and 24 points indicating a moderate risk of falls, and a score below 19 indicating a high risk of falls. 20,21 The questionnaire has been translated and validated for Brazilian Portuguese. 20

Statistical analysis
The normality of the distribution of data was evaluated by the Shapiro-Wilk test. Pearson or Spearman correlation test was performed to analyze the correlation between the balance tools used. All analysis were made using GraphPad Instat software, with p≤0.05. The following values were used to define the strength of correlation: 22 values between 0.0 and±0.3: negligible correlation; values between±0.3 and ±0.5: weak correlation ; values between ±0.5 and ±0.7: moderate correlation; values between ±0.7 and ±0.9: strong correlation; values between ±0.9 and ±1: very strong correlation

Results
The mean age of the sample was 76.91±9.07 years (46.67% female); the BMI was 26.76±3.83. The literates were 75.56% of the sample. As for marital status, there were predominance of unmarried (42.22%) and widowed (37.78%).
The Table 1 shows the mean, minimum and maximum values of the applied tests, besides the cutoff reference values. It is possible to observe that in four tests (TUG, distance-6MWT, GS and Tinetti test) the mean values obtained were outside what is considered normal for the elderly population, indicating a moderate or high risk of falling. Table 2 shows the correlation values between the applied tests. It is possible to observe that there was a correlation between all tests, with statistical significance. [23][24][25][26][27]

Discussion
The present study aimed to investigate the correlation between the instruments to evaluate the postural balance in the elderly living in the nursing homes.
All tests used in the study showed a positive or negative correlation between them, with statistical significance ( Table 2). The majority of the statistical evaluations presented a strong correlation between the balance tests: SPPB and BBS, SPPB and TUG, SPPB and gait speed, BBS and TUG, BBS and gait speed, BBS and distance (6MWT), TUG and gait speed, TUG and distance (6MWT), gait speed and distance (6MWT), distance (6MWT) and Tinetti. In four analyzes, were find a moderate correlation: SPPB and distance (6MWT), BBS and Tinetti, TUG and Tinetti, gait speed and Tinetti. In one analyze, was find a weak correlation: SPPB and Tinetti.
Institutionalized older adults have fewer opportunities to participate in daily living activities and tasks in an independent manner, with greater deleterious effects on the physiological losses inherent to aging and with increased gait and balance impairment compared to community-dwelling older adults. 5, 28,29 Because of this, institutionalized elderly people are at greater risk of falling. Therefore, it is important to know if the instruments used for the evaluation of postural balance maintain a good correlation for this population.
The results show that the instruments evaluated can be used to assess postural balance and to track the risk of falls, as well as to indicate the elderly who need more attention in nursing homes. Of all tests applied in the study, the least used and researched test for postural balance evaluation is the 6MWT.
The 6MWT is a commonly used physical performance measure in clinical research 19 and their performance has been used as a measure of cardiovascular and respiratory exercise capacity. More recently, it has been recognized that the 6MWT may be a general indicator of overall physical performance and mobility in older people. 18,30 Harada et al reported moderate correlations between 6MWD and mobility measures, including standing balance, chair stands, and gait speed in older people. 18 In our study, the 6MWT showed a moderate correlation with the Tinneti and SPPB test and a strong correlation with the BBS, TUG and gair speed.
All instruments used in the study are low cost and easy to apply, presenting positive and negative characteristics. The choice of which test to apply in the assessment of postural balance depends on some important questions: knowledge of the test, space to perform the test, characteristics of the test, among others. The 6MWT, for example, requires a corridor with a minimum length of 15 meters. On the other hand, the BBS, SPPB and Tinetti tests have a ceiling effect, making it difficult to evaluate people with better physical conditions. TUG test have a problem with the standardization of the chair used, as well as the gait speed during the test.
Another important issue in the choice of evaluation tools is: what characteristics of the postural balance one wants to evaluate. The BBS was developed to evaluate abilities in both static and dynamic balance through the direct observation of three domains: sitting, standing, and changing posture. 24 The TUG measures the time (in seconds) necessary for a person to rise from a chair with armrests, walk 3 m at a comfortable walking speed, turn, return to the chair, and sit down. 16 Poor TUG performance has been associated with low muscle strength, poor balance, slow gait speed, fear of falling, and physical inactivity 31 . Gait speed is measured over a relatively short distance and thus does not include endurance as a factor. A subject's ability to increase or decrease walking speed above or below a "comfortable" pace suggests a potential to adapt to varying environments and task demands. The 6MW is used to measure the maximum distance that a person can walk in 6 minutes and the endurance is include as a factor. SPPB consists of three tasks representing standing balance, walking speed, and repeated chair stands. The Tinetti mobility test (TMT) measures static, dynamic, reactive, and anticipatory balance and of ambulation and transfer ability. 32 Then, as each test evaluates different items of postural balance, it is important to apply at least two tests to have a broader assessment of this important subject related to the institutionalized elderly.

Conclusion
The instruments showed a strong or moderate correlation and can be used to evaluate the postural balance in the nursing home residents.