A look at vulnerability in the older population in health sciences studies: a systematic review

O olhar sobre a vulnerabilidade na população idosa nos estudos das ciências da saúde: uma revisão sistemática

Aline Gabrício Marçola aline.gmarc@gmail.com

Faculdade de Medicina do ABC, Brazil

Gabriela Cabett Cipolli

Universidade Estadual de Campinas, Brazil

Danyela Casadei Donatelli

Faculdade de Medicina do ABC, Brazil

Nivaldo Carneiro

Santa Casa de São Paulo, Brazil

Vânia Barbosa do Nascimento

Faculdade de Medicina do ABC, Brazil

The terms frailty and vulnerability are used interchangeably. However, the general concept of vulnerability has come to have a specific meaning in the context of older people.1 Vulnerability is a multidimensional construct in which behavioral, sociocultural, economic, and political conditions interact with biological processes throughout life.2 However, the general level of vulnerability is known to increase during the aging process, with age being a good indicator of health risks in the health care system.3 In a previous review, Barbosa et al.3 reported that vulnerability in older people can be the result of different conditions that correlate with each other, highlighting biological, social, and programmatic factors.

Seidl & Zannon4 systematized the subjectivity of vulnerability in older adults. They highlighted 4 major dimensions that have implications for quality of life: physical, psychological, social relationships, and environmental. These dimensions also need to be considered when analyzing the new demands that arise for maintaining the health of older adults, since their needs, resulting from clinical, functional, social, and family characteristics, may reach a certain depth, requiring different intervention processes.5

Some studies highlight that cognitive impairment, decreased senses (smell and hearing), psychological decline and recurrent episodes of falls and frailty are determinants of vulnerability in older people.6 Regarding frailty, it is characterized by loss of biological reserves, failure of physiological mechanisms, and increased vulnerability to multiple adverse outcomes.7 While there is evidence supporting a view that old age is associated with increased vulnerability, such as in frailty and decreased quality of life, this view has also been criticized for resulting in negative stereotypical views of old age.6 A recent systematic review and meta-analysis showed that, among the included studies, 12% of community-dwelling older people were physically frail.8

Currently, there are observational (cross-sectional and longitudinal), intervention and applied research studies that have analyzed vulnerability in older persons. However, studies systematically exploring the meaning of vulnerability in this population are scarce. Only one scoping review was published in an attempt to synthesize the definitions and instruments used to measure vulnerability in older adults. This review reported that the Perceived Vulnerability Scale was able to provide a common language and measure in health and social sciences research, policy, and practice.9 Our review moves toward looking at vulnerability within individual, socio-environmental, and health care system aspects. Given the complexity and multidimensionality of older people’s vulnerability, the objective of this study was to systematically investigate and review studies that have addressed the concept of vulnerability associated with individual, socio-environmental, and health care system aspects of the older population.

The current systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.10 The study protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on October 2, 2022, with registration number CRD42022361649.

Quality assessment

To assess the quality of cross-sectional and longitudinal studies, we used the National Institutes of Health (NIH) quality assessment tool for observational cohort and cross-sectional studies.12 Questions were answered as “yes,” “no,” or “cannot determine/not applicable/not reported.” Quality was rated as “good,” “fair,” or “poor.” As there are no established cutoff points in the literature for quality rating, the quality assessment score was reported but not used for the selection of studies in the current review. The quality of all studies was assessed twice by 2 independent reviewers. Any disagreements were discussed between the reviewers until consensus was reached. The details of the assessment of study quality are shown in Table 1.3,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37

TABLE 1.
Characteristics of included studies (n=26).

TABLE 1.
Characteristics of included studies (n=26).

SD: standard deviation. *Defined according to Rosero-Bixby & Dow^{13; †}National Institutes of Health (NIH) quality assessment tool for observational cohort and cross-sectional studies. Quality rating was determined by the authors as follows: if the article had 0 to 1 “no” answers, it would be rated as “good”; if the article had 2 to 6 “no” answers, it would be rated as “fair”; and if the article had more than 6 “no” answers, it would be rated as “poor.”

In this systematic review, the identification of the definition of vulnerability in the older population was considered. The database searches resulted in 26 studies, most of which were conducted in Brazil and focused on individual aspects of vulnerability. However, the literature on vulnerability in older people in the field of health sciences is still scarce, according to the articles retrieved during the search period. This issue has been previously raised by Gutiérrez-Robledo & Avila-Funes,5 but no changes have been identified in this pattern in recent years, according to the current review. When studying social vulnerability for determining frailty, those authors stated that studies do not approach the problem from a non-biological framework in the field of biomedical sciences.5 Even so, frailty in older adults has been conceived as a clinical condition with multiple causes, characterized by decreased strength, resistance, and physiological function, which can lead to dependence and physical, cognitive, and social decline.41

Rosero-Bixby & Dow,13 for example, sought to determine the factors that could influence the health of older Costa Ricans based on socioeconomic status gradients in different health conditions in the older population. In a longitudinal study, they evaluated 8000 older people using mortality and the prevalence of several health conditions and anthropometric biomarkers, as well as blood and urine samples. The ultimate health indicator revealed that better educated and wealthier individuals are worse off, presenting with metabolic syndrome and risk of death. In contrast, measures related to quality of life, such as functional and cognitive disabilities, physical frailty, and depression, worsen with lower socioeconomic status. However, the relationship between the concepts of vulnerability and fragility was not clear, and the authors only restated that fragility is the result of a series of interconnected conditions, which may be called conditions of vulnerability.

In this direction, the relationship between vulnerability and frailty has not been clearly reported, as observed in the included studies. The current analysis showed that most studies presented these terms as synonymous when addressing participants’ physical deficits, but they were also used independently when each one contributed independently to an event that could compromise the quality of life of older people. In addition, the terms were reported in an associated manner when one condition contributed to the outcome of the other.

Bolina et al.28 defined “vulnerability” as a term used to designate the susceptibilities of people or communities to health problems and damage. Moreover, this concept may be formed in 3 interdependent levels — the individual, the social, and the programmatic: individual vulnerability is characterized by biological, behavioral, and affective aspects that increase an individual’s susceptibility to adverse health outcomes; the social component is related to the interference of the socioeconomic and cultural contexts; and the programmatic component refers to the way in which policies, programs, and health services influence the problem in question. Based on this definition, the authors chose to use a combination of questionnaires that assessed the 3 levels of vulnerability. Consequently, the main results of the study were associated with the definition of the term presented in the introduction and the chosen methodologies.

Supporting the breadth of the concept, Barbosa et al.3 pointed out that, in the case of aging, there is an increased risk for the development of biological or individual vulnerability of socioeconomic and psychosocial nature due to the biological decline typical of senescence. In this respect, individual vulnerability may be related to other factors, but the study directed its focus to evaluating and measuring “vulnerability” as a biological phenomenon. Thus, the authors chose to use the Vulnerable Elders Survey (VES-13) as the main questionnaire, which assesses self-perceived health, presence of physical limitations, and functional decline in older people, classifying them as vulnerable or non-vulnerable. With the application of this questionnaire, their main results were within a category different from that presented by Bolina et al.28

The definitions of “vulnerability in older people” varied within each article individually, including the issue of the frailty syndrome previously discussed, which makes the standardization of results a challenging task. Nevertheless, most studies addressed the concept of vulnerability in the older population as an individual issue, whether biological or psychological, although, in their rationale, many studies approached the term as a multifactorial and plural concept. The inclusion of concepts involving vulnerabilities in studies on the health of older people might provide deeper reflections and increase the production of evidence, which should prompt us to look beyond the individual aspect. It means involving the historical dimension, social relationships, and subjectivity in order to produce new knowledge to face health risks, as well as to support the development of public policies aimed at improving the living and health conditions of the older population.42

This review has some limitations to be considered, as it is a systematic review addressing a broad and complex topic. It is a strength that many different articles have been evaluated in different databases. However, although 3 large databases were selected for the literature search, it might have been more useful, considering the analysis and systematization of results, to include 1 or 2 additional databases in the initial search strategy. The absence of these additional databases may be seen as a limitation of this review. In addition, the majority of the included studies were cross-sectional, showing that there were difficulties in analyzing a cause-and-effect relationship between certain vulnerabilities and their possible consequences.

In the current systematic review, we observed that the concept of “vulnerability in older people” was not properly defined in the biomedical scientific community. For this reason, the methodologies used in each article and the main results extracted varied widely, allowing multiple approaches. Nevertheless, the majority of the included studies addressed vulnerability in its individual aspect, whether biological or psychological. Therefore, when we return to the guiding question of this review, “How have the conditions of vulnerability of older people been approached in observational studies?”, we can rightly conclude that these conditions are being treated broadly and using a wide variety of methodological strategies. Even so, the focus on the individual aspect of vulnerability is clear, denoting a strong limitation in studying older individuals as a whole, in the various contexts within which they are embedded. In light of this review, clinical and research professionals need to look at vulnerability as a complex and multifactorial phenomenon in order to systematize vulnerability in its multiple aspects (individual, socio-environmental, and health care system). This way, the strategies to assess vulnerability in the older population may be both effective and efficient.