Evaluation of the clinical-functional vulnerability index in older adults

Objective: To evaluate the clinical-functional vulnerability index (CFVI) of older adults and its relationship with socioeconomic, behavioral, clinical and therapeutic indicators. Method: A cross-sectional epidemiological study with a quantitative design was performed with 318 randomly drawn older adults registered with the Family Health Strategy. Data were collected through the CFVI-20 questionnaire and analysis was supported by descriptive, bivariate and multivariate statistics, with results with p-value <0.05 considered significant. Results: most older adults (59.1%) were considered frail or potentially frail. Among the groups studied, there was a statistically significant difference in the CFVI for the variables age group (p<0.001), functional literacy (p=0.001), alcohol consumption ( p<0.001), physical exercise ( p<0.001), self-reported health problems ( p<0.001) and medication use (p<0.001), as well as a positive correlation with stress (r=0.135; p=0.016). In the multiple linear regression model, the set of sociodemographic predictor variables explained the frailty of the elderly by 30.4% (R2=0.304). Conclusions: The advancement of age, as a non-controllable variable, indicates a need to encourage the maintenance of functionality in old age, based on the health care strategies that prolong longevity with safety, autonomy and vitality.


INTRODUCTION
Population aging is a contemporary reality that has occurred at different times and magnitudes in practically every country in the world¹. The contingent of elderly people, evidenced on a global scale, especially in Brazil, has expanded considerably and rapidly, bringing important changes to how society is established².
According to the Brazilian Institute of Geography and Statistics (or IBGE), older adults represent the portion of the population with the highest growth rate, especially in recent years³. In 2019, there were more than 32 million older adults in Brazil, and it is estimated that by the year 2025 the country will have the sixth largest contingent in the world 4 . This demographic scenario is mainly due to a more significant decline in mortality and fertility rates 5 .
Consequently, the increase in life expectancy has generated changes in the illness profile of older adults, with a predominance of chronic non-communicable diseases (CNCDs) 6 , in addition to an increase in degrees of dependence and disabilities. The changes that occur in the body, whether morphological, functional, biological or psychological, promote a decrease in functional capacity (FC), which in turn promotes greater vulnerability and a higher incidence of diseases, especially CNCDs 7 .
FC is defined as the ability of an individual to perform activities that allow them to exercise their autonomy and independence 8 . When an individual is in a frail state, the chance of being affected by comorbidities increases, thus augmenting the risks of falls, infections, hospitalization, institutionalization, disabilities and death, requiring, therefore, urgent health interventions 9 .
Thus, the clinical-functional vulnerability index (CFVI) is an essential tool for identifying the functional impairment of older adults and their needs. Assessment with the tool represents a systematic attempt to objectively verify the capacity of an individual to perform the activities necessary to care for oneself, based on the evaluation of different skills, and, therefore, allows the development of an interdisciplinary health care plan especially aimed at the optimization of the performance of older adults 10 .
The objective of the present study was to evaluate the clinical-functional vulnerability index in older adults, based on its relationship with socioeconomic, behavioral, clinical and therapeutic indicators.

METHOD
The present study consists of a cross-sectional observational epidemiological investigation with a quantitative approach, carried out in the municipal region of Cuité (Paraíba, Brazil), located in the Western Curimataú microregion. Based on a total population of 3,041 elderly people in the municipal region, the sample calculation resulted in an equivalent number of 342 required participants, considering a 95% confidence level and a 5% sampling error. With the exception of sample losses and refusals, 318 elderly people monitored by Basic Health Units (BHUs) participated in the study and were selected through a systematic probabilistic sampling model. Two inclusion criteria were considered: age of 60 years old or older; and be properly registered with the Family Health Strategy (FHS).  11 . To identify the older adults in the study, a survey of the addresses of the homes of the participants was carried out, with Community Health Agents helping to identify the locations. The interviewees were informed about the aspects covered in the research and their own contribution to the study. After any queries were resolved, an Informed Consent Form (ICF) was duly signed by the participants. The chief researcher, the participating researcher and seven students from the Center for Studies and Research in Aging and Quality of Life (or NEPEQ) took part in data collection.
Two instruments were used to obtain the information: I) a sociodemographic, behavioral and clinical-therapeutic questionnaire, which included the variables: age, sex, skin color/race, marital status, education, family income, family arrangement, current occupation, body mass index, alcohol consumption, smoking, physical exercise, stress level, use of health services, use of medications and self-reported health problems; and II) Clinical-Functional Vulnerability Index 20 (CFVI-20), which includes multidimensional aspects about the condition of older adults, comprising 20 items distributed in eight sections (age, self-perceived health, functional disabilities, cognition, mood, mobility, communication and multiple comorbidities). Each section is assigned a specific score, totaling a maximum of 40 points 12 . The clinical-functional evaluation of older adults is determined as follows: a) 0 to 6: robust older adults; b) 7 to 14 points: older adults with risk of frailty; and c) ≥15 points: older adults in a frail condition, suffering functional decline and unable to manage their life 13 .
The data were entered and processed in the IBM SPSS (Statistical Package for the Social Sciences) software package version 20, to allow descriptive (univariate) and inferential analysis of the results that related the dependent and independent variables (outcome).
The Mann-Whitney and Kruskal-Wallis tests were applied when processing bivariate statistics in order to compare the difference between the groups with respect to the outcome (IVCF), while the Spearman Correlation Test was used for combinations of quantitative variables, with significance represented by p-values of less than 0.05. It Non-parametric tests were used as the set of quantitative data did not present normal distribution according to the Kolmogorov-Smirnov test. In the multiple linear regression model, the total CVFI score was considered as the outcome and the set of sociodemographic, behavioral and clinicaltherapeutic variables were deemed the predictor variables, thus allowing the adjustment of the model based on the category of the variables previously identified as statistically significant and defining the coefficient of determination.

RESULTS
For the overall assessment of CFVI, the measures categorized from the calculation of the total score of each participant were used. The results of the stratification of the CFVI-20 are shown in Table 1.
The highest percentage of elderly people in the study were robust (40.9%), however the sum of frail and potentially frail elderly people totaled 59.1%, representing the majority of the older population of Cuité.
In order to substantiate the results found in CFVI categorization, the descriptive analysis of the total score was also considered, as can be seen in Table 2, in which a mean score of 9.90 and a median score of 8 indicate potentially frail older adults (score from 7 to 14 points). To identify the relationship between the CFVI and the socioeconomic, behavioral, clinical and therapeutic characteristics of the older adults in the study, 15 hypotheses were tested that allowed inferences between the different groups studied to be identified and elucidated the set of explanatory variables for the variation in the CFVI among the older adults. The results are shown in Table 3.
When comparing the difference between the groups in terms of CFVI, statistical significance was observed for the variables age group ( p<0.001), functional literacy ( p=0.001), alcohol consumption ( p<0.001), physical exercise ( p<0.001), self-reported health problems ( p<0.001) and medication use ( p<0.001).
For the quantitative independent variables, tests of correlation with the CFVI were performed. The results are shown in Table 4.
There was a significant linear relationship between the CFVI and the variables years of schooling (ρ= -0.151; p-value=0.007) and self-reported stress (ρ=0.135; p-value =0.016). Between the variable years of schooling and the CFVI, a negative (inverse) correlation was identified, in which elderly people with lower education had higher CFVI scores; for the self-reported stress variable and the CFVI the correlation was positive, suggesting a higher prevalence of stress among those with greater frailty.
In the multiple linear regression model, considering the total CFVI score as the outcome variable and the set of sociodemographic, behavioral and clinical-therapeutic variables as the predictor variables, the model was adjusted by category of variables, only included those whose significance statistic was previously identified. The result is shown in Table 5.   The set of sociodemographic predictor variables has the highest Coefficient of Determination, with R 2 =0.304 or 30.4%. This confirms that the sociodemographic conditions represented by the variables age group and functional literacy, explain the frailty of the older adults, according to the CFVI, by 30.4%. It is worth mentioning that, taken alone, age group is the main variable responsible for explaining the variation in CFVI (29.1%).

DISCUSSION
The impairment of FC and/or its effective risk clearly elucidated in the findings (59.1% of frail and potentially frail elderly) serves as a warning regarding the need for public policies aimed at the health of older adults, as well as for researchers, managers, health professionals, family members and society in general, so that health promotion and disease prevention measures are adopted to improve the autonomy and independence of this group.
The robust elderly are those who manage to exercise their autonomy and independence without exhibiting a decline in FC; potentially frail elderly person have suffered a reduction in FC, while they can exercise autonomy and independence, there are chances of a risk of functional dependence; and frail older adults exhibit some decline in FC, and are unable to manage their life independently and autonomously 14 .
Another study found that older adults were frail or potentially frail, when compared to robust elderly 15 . In a study conducted in the municipal region of Pombal (Paraiba), there was a predominance of potentially frail elderly 9 . Frailty increases the chances of older adults being affected by an adverse health event, meaning that greater care should be aimed at the risk of functional decline 16 . This decline, when viewed as a health problem for older adults, requires progressively strengthened coping strategies as the individual ages 17 .
In order to alleviate the effects caused by aging and to stimulate actions that promote the quality of life (QoL) of this population, the National Health Policy for Older Adults (or PNSPI) addresses the need to recover, maintain and promote the autonomy and independence of this portion of the population, through collective or individual measures, based on the principles and guidelines of the National Health System (or SUS) 18 .
When the data was analyzed in relation to age, it is observed that most of the participants (60.4%) were part of the young group of elderly people (60 to 74 years old), who are characterized as potentially active and have a participatory role in society. When comparing age group and CFVI, the highest mean rank was identified among older adults aged over 90 (278.76) with a statistically significant difference between the groups ( p<0.001). Clinicalfunctional vulnerability and age group have a directly proportional dependency relationship.
In a study conducted in Fortaleza (Ceará), it was found that age is a predictive factor for the functional disability of older adults 19 . As age increases, basic and instrumental activities are affected. The greater the age, the greater the changes in the natural aging process, as well as the greater the limitations related to functional capacity. Elderly people aged 80 years and over also exhibited greater chances of having some functional impairment 20 .
In terms of the variable functional literacy, it was found that 69.5% of the interviewees were classified as functional illiterates, with a mean of 2.79 years of schooling. This fact negatively affects old age, especially in the capacity for social insertion and access to means of care. Corroborating this finding, another study found that 76.48% of older adults had an educational level of up to four years of schooling, considered very low 21 . This social determinant potentiates the vulnerability of the individual when affected by certain diseases, as the lower the level of education, the greater the prevalence of functional disability, mainly due to the involvement of CNCDs 22 .
Still regarding functional literacy, when comparing the different groups, based on statistical significance ( p=0.001), the highest CFVI mean rank was among illiterate elderly (170.86), suggesting education is an important determinant for the maintenance of vitality and successful aging. Functionally illiterate elderly people exhibit greater clinical-functional vulnerability. Similar data were found in a study in which participants with low schooling had a greater decline in FC 23 .
In order to improve the understanding and QoL of elderly people with low education levels, health professionals should assess the understanding and interpretation of health education actions, especially due to the difficulty of understanding some instructions 23 . In addition, this determinant impairs the adherence of healthy habits on the part of these elderly people and, therefore, promotes an increase in the use of health services due to the serious impairment of chronic disabling conditions that could have been prevented over time 24 .
Regarding the consumption of alcoholic beverages, 88.1% of older adults did not drink alcohol. A study carried out in the state of Michigan (USA) found that alcohol consumption was associated with a lower risk of worsening frailty 25 .
The highest mean rank was observed among individuals who did not consume alcohol (168.24), suggesting that older adults who did not consume alcohol had a higher CFVI score, that is, they are more frail. Although there is no causal relationship, older adults who consume alcoholic beverages showed greater vitality, which is justified by the fact that this portion is composed of active, autonomous, independent people with good functionality. While the consumption of alcoholic beverages is considered something harmful to health, depending on the amount consumed and the situation, this habit can be related to the greater participation of older adults in social activities, indicating the maintenance of functionality 26 . mean rank was found among those who reported using medication (182.39), confirming that this group has a more frail FC.
Reinforcing these results, a study carried out in Erval Seco (Rio Grande do Sul) found that a large proportion of older adults interviewed reported making continuous use of medications, since they were frail or potentially frail 31 . In order to facilitate the maintenance of drug therapy and prevent damage or complications to older adults from the use of these drugs, health professionals can offer educational resources, guiding older adults in the best possible way, so that they can at least understand the dosage and the frequency to be followed 8 .
The occurrence of stress is related to the incidence of cognitive deficits, which can be expressed in a very harmful manner among older adults 32 . It is common that the decline in FC causes stress in an individual, since the older person has a change in identity, as well as in their body image. Thus, it can be said that FC directly influences the mental health of older adults, as it is linked to the performance of the activities of daily living (ADL) of the individual 33 .
In multivariate analysis, advancing age is shown to be an important risk factor for the decline of FC in older adults. This risk is explained by the decline in the functionality of the physiological systems that determine an individual's FC, which in turn will decline as age advances. From this perspective, it can be said that this relationship between advancing age and the decline of FC is simply a phenomenon common to older adults, thus requiring the development of strategies such as the follow-up care and monitoring of this population, aiming at lessening or avoiding these limitations 34 .
The World Health Organization (WHO) has warned that healthy aging should be considered a global priority, thus promoting the development of strategies to deal with the health problems of this population and the impact of CNCDs on the QoL of older adults 35 . As age is a variable that cannot be controlled, it is necessary to train health teams to care for this population, thus guaranteeing the maintenance of the functionality of older adults, in order to safely prolong longevity, autonomy and vitality.
Regarding the practice of physical exercise, the majority of older adults (55.0%) did not perform any type of activity. However, the percentage of elderly people who did practice physical activity is relevant (45.0%). It is worth mentioning that the performance of physical exercise frequently has numerous health benefits, both physical and psychosocial, and constitutes an effective way of preventing the occurrence of future diseases 27 .
In the comparison between the groups, the highest CFVI mean rank was among sedentary individuals (183.87), suggesting that the practice of physical exercises is directly related to the maintenance of the FC among older adults, ratified by statistical significance ( p<0.001). Sedentary elderly people have a higher prevalence of the decline of CF. Greater physical inactivity and the prevalence of CNCDs create a vicious circle between disease and disability 28 .
The decline in FC among older adults results in a reduction in resistance and a worsening of motor performance. Therefore, it is important to adopt measures to implement preventive actions such as physical exercise, since this intervention can improve, stabilize or even reverse this phenomenon, reducing the risk of falls and, consequently, improving the mobility and muscle strength of older adults 29 .
The variable self-reported health problems showed that a significant majority of older adults (79.9%) reported suffering a health problem. In the comparison between the groups, the highest CFVI mean rank was found among older adults who self-reported having health problems (172.37), indicating that FC was more affected than in the opposite group. The statistical significance of this finding reveals that health problems are considered a determinant of FC in older adults.
Regarding the variable medication use, it was observed that 69.5% of the older adults reported using medications. The impact of chronic diseases on older adults transforms this public into large-scale consumers of health services, as well as increasing their use of medications. This population, in turn, is the most medicalized part of society and the group with the greatest signs of the incidence and prevalence of comorbidities 30 . When comparing the difference in CFVI between the groups, a higher As a technical limitation of the present study, the difficulty in locating the older adults selected through the sampling procedure should be mentioned, especially in rural areas. However, with the effective collaboration of community health agents in the municipal region, this difficulty was gradually overcome.

CONCLUSION
Regarding the Clinical-Functional Vulnerability Index, the findings reveal a significant set of frail or potentially frail elderly people who deserve prioritized and qualified care in all social and health dimensions, in order to enhance their functional capacity.
Among the set of variables studied, it was statistically found that advanced age, physical inactivity, functional illiteracy, high stress, the presence of health problems and the use of medications are factors associated with clinicalfunctional vulnerability in older adults. In the multivariate model, the sociodemographic conditions represented by age group and functional literacy explain the frailty of the older adults, as identified by the Clinical-Functional Vulnerability Index, by 30.4%.
It is suggested that other studies should be devised and executed to assess the functional capacity of older adults, in order to improve the robustness of scientific knowledge in this area and encourage the adoption of measures to promote health and prevent diseases to enhance the autonomy and independence of older adults, thus ensuring a better quality of life.