The COVID-19 pandemic brought about changes in personal and social habits unprecedented in this century and altered the social and health balance of affected countries. In Spain, nationwide lockdown was decreed on March 15, 2020. This measure slowed the spread of the pandemic but had an impact on people, especially dependents (1).

Dependence is a vulnerability criterion that increases the risk of hospitalization and death (2). Although confinement affected all population groups, dependent people were among the most sensitive to this situation since their dependence is associated with greater age and comorbidities, which were risk factors for morbidity and mortality due to COVID-19 (3–5)^. Further, the risk of contagion is probably greater among dependent populations, especially those institutionalized, due to the need for interaction with others for care (6).

Apart from the COVID-19 pandemic, dependency is an emerging socio-health problem that requires multiple socio-health resources, with a progressively increasing cost, and with two models of care, depending on whether the dependent persons reside at home or are institutionalized in nursing homes. To maintain equity in the care of both groups, it is necessary to carry out adequate healthcare planning and evaluate the actions carried out (7). The 20th Report of the State Observatory on Dependency (8), February 2020, states that 3% of the Spanish population needs support to perform basic activities of daily living (ADL), most of this population being female. At the healthcare level, care for dependency falls on primary care nurses, the main clinical manager of this multidisciplinary problem (9).

However, dependency is not a standalone issue and requires a broader approach. Chronicity, complexity, and dependency form an increasingly prevalent interrelated triad in our society (10), contributing to the creation of vulnerable populations and social inequalities (11). Thus, in a pandemic, with the added factor of confinement, new conditions and rules of the game were created, which need to be analyzed to design strategies that will enable us to deal with these situations in the future.

The new rules of social and personal functioning and supervision, for which no one had an adaptation period, included the elimination of visits by relatives to those not strictly necessary, leaving food at the door, the loss of attention in day centers, and the suspension of home care performed by hired caregivers. These changes aggravated the loneliness of the dependent adults and forced them to perform functions and responsibilities that they had not before. All the above was added to the fear generated by the media bombardment, showing a high mortality rate among people like them. All the above factors impact the physical and mental health of people, which requires further analysis (12, 13).

Although previous studies have examined institutionalized dependent populations (14–16) or involved research before and after hospital discharge (17, 18), generally in association with patient interventions (19), there have been fewer longitudinal studies of non-institutionalized dependent populations in the context of the COVID-19 pandemic. A 2019 study addressed the complexity of these factors and their interrelationships (20). The current study aims to analyze whether the nationwide lockdown, which was declared under a state of alarm by the Government of Spain, conditioned short- and long-term changes in the functional dependence of the dependent population of the Orcasitas neighborhood of Madrid (Spain), and to quantify the relationships of these changes with sociodemographic variables and survival at 3 years.

The COVID-19 pandemic was the reason for carrying out this study, which made visible an already pre-existing situation, that of a population that was to a certain extent invisible, with a high mortality rate, and about which there was a great lack of knowledge. This lack of knowledge led to the prediction of results that reality showed to be radically different. The confinement and the risk of death due to the pandemic produced an awakening in the functionally dependent population of the Orcasitas cohort as a form of resilience in the face of adversity. This awakening, in response to the challenge posed to the functionally dependent population by being locked in their homes for months at a time, was observed across all ages and showed a non-significant tendency to become less frequent as the group analyzed got older.

The way in which older people lived in their environment influenced the level of functional improvement observed. A significant trend toward greater functional improvement was found among people living alone or with a partner, compared to those living with their children or others. Having fewer social support resources forced these people to respond to adversity in a way that people who did have these resources may not have needed since their cohabitants covered their basic subsistence needs.

In addition to making it possible to visualize a vulnerable group due to their frailty, this study provided relevant results on a diagnostic tool that is easy to use and inexpensive, the Barthel index. This tool showed its full potential as a predictor of short-term mortality during the COVID-19 pandemic (2, 18–20, 24–28). In this study, it was also a good predictor of medium- and long-term mortality (27–29). These results place the Barthel index at an advantage as a tool for detecting at-risk populations in health planning (20, 27–29) and in risk assessment in multiple clinical situations requiring discriminating the risk of adverse events.

In older persons, functional dependence is associated with greater mortality (24, 25), and this study showed that this risk was significantly higher in men than in women and that it was greater the higher the level of dependence (26, 27). These results are similar to those reported in other studies and show that age and sex influence the development and progression of functional disability (28). However, sex, age, and dependence are not isolated factors; rather, they evolve in a context that, as other studies have also reported, influences the observed results (29). The context described in this cohort is an unfavorable social environment, consisting of a suburb of the capital of Spain with an aging population, in which one in five people is 65 or older, and with a large group of people over 80 years. This environment was complemented by unfavorable economic and cultural indicators. The population with functional dependence in the Orcasitas cohort had a low socioeconomic level, which placed almost half of them in the vicinity of the poverty threshold; in 2020, the poverty threshold in Spain was 9,626 euros/year. In addition, they shared a low cultural level, with almost all the dependents in this cohort having an insufficient level of education.

It is in this social environment that the nationwide confinement by COVID-19 took place, with an unexpected effect observed in the population with functional dependence due to this confinement: improvement in functional capacity to perform basic activities of daily living. Although initially this response could be considered a temporary adaptive response to a stressful event that put survival at risk, longitudinal follow-up showed that it involved greater changes. Changes were observed not only in the persistence of improved functional dependence at 3 years but also in that many people ceased to be dependent after confinement and maintained and regained functional independence in the long term. Such changes were relevant in terms of survival.

The presence of a very old dependent population that potentially has few cultural and economic coping tools in an environment of home confinement was expected to worsen baseline conditions (30–32), which occurred during the pandemic in institutionalized patients (33–36). However, in the non-institutionalized dependent population of the Orcasitas cohort, nationwide COVID-19 lockdown triggered an “awakening” phenomenon, developing survival defense mechanisms that made it possible to improve their functional capacities, with a direct effect: half of the dependent persons in this cohort ceased to be dependent. This result was also observed in people with total dependence, in a more moderate form and in relation to their important limitations. This change left a visible imprint as a sawtooth in the functional assessment conducted with the Barthel index between 2020 and 2023. Research on the pandemic and home confinement has shown that dependency is a dynamic process that is susceptible to intervention (37), and that there is no age limit for this intervention.

In addition to the data described above on the social environment, the population of Orcasitas came from a socioeconomic immigration background to the outskirts of large cities in the middle of the last century and lived for many years in substandard housing or shantytowns. These individuals were the first marginal population group to design their own housing for rehousing in the 1970s and 1980s, forming a social group with a markedly vindictive nature that may have generated an important resilience in the face of adversity (37, 38), which could justify the improvement described. On the other hand, the loss of support resources, such as daycare centers or home-help assistants, forced them to carry out activities that they had not previously done, a situation that has been described as increasing resilience (39) and which did not happen in nursing homes (40).

The intervention of protective psychosocial factors acquired prior to exposure to the new stressor posed by the COVID-19 pandemic has already been described in other studies (41) and probably played a relevant role in the fact that the results observed in this study did not describe functional deterioration. This deterioration is usually the predictable outcome when people with frailty are subjected to prolonged stressors and was observed during COVID-19 pandemic confinement in institutionalized individuals or those requiring hospital admissions, including admissions for COVID-19 (2, 27, 32–35, 42, 43). These living situations (nursing home, hospital) generally entail an added dependence on third parties (nursing home staff, health professionals), which can affect the person's own self-concept (43) and the innate resilience or resilience developed over the course of life, making its protective effect less visible or non-existent (44).

The increase in life expectancy has led to the appearance of new factors, which may have influenced the results observed in this study. These factors, such as subjective age (the age the patient feels he or she is), subjective aging (how the individual perceives his or her own aging process), and, in age groups as advanced as this one, the role of the subjective proximity of death (45, 46) probably play a role in the life history observed.

However, the data obtained also show that not all the dependent population behaved in the same way in the face of the stressor event of the COVID-19 pandemic, and these differences could be based on Antonovsky's theory of salutogenesis (47, 48), with implications in relation to survival. Beyond the classic coping strategies, part of this population, due to their origins, their life history (poverty at birth, emigration, living in substandard housing, unemployment, low or no education, low income), and their constant struggle to get by, would have developed a chronic adaptive resilience—resilience that they applied daily to survive in permanent adverse living conditions. This vital evolution would have generated psychosocial resources and even biological and material resources not studied (subsistence economy), which would be included within the so-called General Resilience Resources of Antonovsky and would have ended up giving a Sense of Coherence to their lives even in adversity. These resources would remain active or latent, depending on the person's basal state and degree of dependence, and the COVID-19 pandemic brought them to light. Its effect would be reflected in the person's capacity to make the necessary changes to improve his or her functionality, trying to survive the pandemic, changes that were recorded in this study employing the Barthel index, and for which age was not a limiting factor. However, this response showed that these changes had a result not only in terms of functionality but also in terms of survival, so those who made the changes were more likely to stay alive in the long term. This situation was observed in this study not only among women with moderate dependency, who improved their functional capacity during confinement and significantly increased their survival, but also in the observation that those who had the capacity to make positive changes and did make them, had a higher representation among those who survived to 3 years.

Functional dependence is a progressive process clearly associated with high mortality. The COVID-19 pandemic was relevant enough to motivate these people to face it within the “sense of coherence” proposed by Antonovsky. These people, despite their dependence, had the capacity to rearrange themselves again to survive. This capacity for improvement was independent of age, previous disease burden, and the presence of polypharmacy and was observed at all levels of functional dependence. These changes not only had short-term but also long-term effects. For instance, it implied that people who were functionally dependent before the pandemic ceased to be so with the pandemic and maintained this change over time, some of them being functionally independent 3 years later. All of this was in a context with a mean age of 86 years.

This functional improvement at the cohort level allowed them to gain time as the group currently has slightly better functionality than in 2020, even though almost half of the cohort died in this triennium.

In this line, the mean age of this cohort was advanced, and a high abandonment rate was to be expected due to the mere fact of natural deaths due to age (at the end of the study, the mean age, if no one had died, would have been 89 years, well-above life expectancy in Spain). However, among the non-dependent population over 80 years of age, the same abandonment rate was not observed, so being over 80 years of age and being functionally dependent was probably a risk factor for mortality. This cannot be confirmed in this study because the abandonment rate in the non-dependent population includes both deaths and changes of residence outside the Orcasitas neighborhood.

Mortality was higher in men, and although at the general population level, men have a lower life expectancy than women (49), other causes cannot be ruled out for the different mortality by gender observed in the dependent population. As expected, mortality was also higher in persons with greater functional dependence.

For non-institutionalized dependent patients, being included as a total dependent is equivalent to being placed on the threshold of death. The final causes of this mortality, its evolutionary course, and the actions developed by the different agents involved in its follow-up have been the subject of few studies. Moreover, this high mortality rate is not usually made visible by society, which associates it with aging itself, favoring ageism that increases social inequalities (7).

Although the percentage of non-institutionalized older persons with functional dependence might not seem to be high compared to the general population of the same age, the high mortality rate observed in this group makes it advisable to implement changes in health planning to address this problem. This problem, although not strictly health-related, form part of the holistic care that Primary Health Care should provide citizens to maintain equity in care. Above all, an environment where the aging of the population is likely to increase in functional dependence, justifies these actions.

Suggested changes to the current model of care for older persons with functional dependence are supported by the evidence observed in this study that there is room for improvement, there is no age limit for improvement, and this improvement influences long-term survival. Other studies also observe positive changes in long-term functional dependence through proactive actions in these persons (50).

The Barthel index is a simple method of assessment and, as confirmed by this study, it allows easy discrimination of population risk (19, 26, 42), being a good predictor of medium- and long-term mortality (27, 51, 52) and justifying its use to discriminate at-risk populations in health planning (19, 26, 41). In this study, we used two methods for assessing the Barthel index: the classic method, which consists of four levels of dependence, and the method that establishes two levels of dependence, with a cutoff point at Barthel 40. The justification for this approach is 2-fold: on the one hand, to favor comparison of the results of this study with those of other studies, and, on the other hand, to allow health planning to benefit from this double criterion to establish the appropriate indicator in relation to survival.

This study unified the risk levels “total dependence” and “severe dependence” into a single level of severe dependence with a cutoff point of 40 on the Barthel index. This showed greater discrimination in terms of the risk of death. This result, supported by the guidelines of some health systems (23, 51, 53), allows us to recommend using this criterion in medium- and long-term health planning to obtain better health results. The discriminative power of the Barthel index as a test seems to increase as the cohort follow-up is prolonged, as in parallel, each of the items that make up the scale.

A limitation of this study is that the sample size and follow-up time did not allow us to reach greater statistical significance. This could perhaps be present in larger samples or over longer times. Another limitation of the study is that non-parametric estimates of the AUC tend to be underestimated when data from discrete rating scales are used, such as those included in the Barthel index (54).

Evaluating the Barthel index, the pre-confinement level prior to March 2020 was taken as a reference to avoid the biases of the pandemic, the loss of attendant care for domestic work, and the high variability of care of non-cohabitating children toward their parents in this phase. These factors caused a “storm” among dependents, and their effect on the items comprising the Barthel index was not predictable.

The time variable had its effect on this baseline state, “filtering” in terms of survival of those items that are most related to it and highlighting those on which health planning should have an impact to minimize its impact and improve the quality of life of these people. As the components of this population died, this filter effect on the time variable showed its potential, allowing us to detect new questions about the indisputable value of the Barthel index, such as the extent to which the loss of mobility is the factor that leads to this higher mortality among people with functional dependence.

The role of each item of the Barthel index in identifying the most vulnerable patients should be established. Furthermore, items that assess instrumental ADLs should be integrated to provide more individualized care to provide equivalent care for non-institutionalized people with dependency and those in institutionalized care (54).

In summary, unexpected confinement that was forced on this cohort did not have the same effect on functional deterioration as that produced by other sudden events, such as hospital admission (3, 18) or institutionalization (16). Nor was it associated with progressive deterioration associated with age and comorbidities (9, 10), social isolation (20, 27, 55), or the situation of loneliness that affects many of our older people (56). A stressful situation, such as a pandemic, triggers response mechanisms to ensure survival—mechanisms that are present in all individuals, regardless of their level of dependence (35). The results for the Orcasitas cohort, in line with what is proposed in Antonovsky's theory of salutogenesis (57, 58), indicate a resilient population that shows strength in an unforeseen situation and attempts to give the best of itself to be able to move forward (38). Longitudinal studies are needed to analyze the characteristics of the non-institutionalized functionally dependent population and establish policies to improve the quality of life of this population group (54, 59) and to move away from the stereotypical image of dependent persons who consume many resources without contributing anything, promoting their integration in the face of growing social discrimination based on ageism (60).

The functionally dependent population that is not institutionalized in nursing homes and remains in the community is a group that is, to some extent, invisible in epidemiological studies. Advanced age, and especially very advanced age, such as that of this cohort, predisposes us to assimilate that mortality is part of the normal evolutionary course. Similarly, we assimilate the loss of functional capacities as normal. However, accepting these premises should not imply doing nothing to improve the quality of life of these people. Perhaps the main result of this study has been to show that there is a capacity for improvement at any age. And that this capacity for improvement is maintained at all levels of functional dependence. Stereotypes and labels can be a source of inequalities. Against ageism, integration, the promotion of the maintenance of social roles, and the development of activities that encourage the maintenance or recovery of functional capacities may be the appropriate strategies to maintain equity in the care of our older people.

The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding author.

The studies involving humans were approved by Center Local Research Commission of the Primary Care Management of Madrid (reference number 16/20-C-Bis) on June 29, 2020. The Ethics Committee of the Hospital provided approval by resolution CEIm 23/501 dated September 26, 2023. The studies were conducted in accordance with the local legislation and institutional requirements. Written informed consent for participation in this study was provided by the participants' legal guardians/next of kin.

VM: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. MM: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. MF: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. AM: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. MB: Conceptualization, Data curation, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. HA: Conceptualization, Formal analysis, Project administration, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. EP: Conceptualization, Data curation, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. LC: Conceptualization, Data curation, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. SG: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. ESá: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. ESe: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. IS: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. MR: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. JH: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing. IL: Conceptualization, Formal analysis, Methodology, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing.

Vicente Martín Moreno, Orcasitas Health Care Center and i+12 Research Institute of the Doce de Octubre hospital; GIDO group co-director, Madrid, Spain; María Inmaculada Martínez Sanz, Orcasitas Health Care Center; GIDO group co-director, Madrid, Spain; Miriam Fernández Gallardo, María Palma Benítez Calderón, Helena Alonso Samperiz, Elena Pérez Rico, Laura Calderón Jiménez, Sara Guerra Maroto, Elena Sánchez Rodríguez, Eva Sevillano Fuentes, Irene Sánchez González, Julia Herranz Hernando, and Irene León Saiz, Orcasitas Health Care Center, Madrid, Spain; Amanda Martín Fernández, Polibea Concert, Madrid, Spain; Miguel Recuero Vázquez, Orcasitas Health Care Center and Nursing Home Care Unit of the Center Assistance Directorate, Madrid, Spain.