In this study comprising the noninstitutionalized elderly Brazilian population, the prevalences of moderate and severe dependence for BADL were 10.2% (95% CI, 9.6–10.7) and 4.8% (95% CI, 4.4–5.2), respectively. For IADL dependence, the prevalences were 13.8% (95% CI, 13.1–14.4) and 15.6% (95% CI, 14.9%–16.2) in moderate and severe dependence, respectively.
The studied chronic diseases demonstrated an important association with dependence on both BADLs and IADLs. Elderly individuals with three or more coexisting chronic diseases were 78% more likely (95% CI, 1.14–2.78) to be severely dependent on BADLs and 70% (95% CI, 1.27–2.26) more likely to be dependent on IADLs compared with their peers without chronic diseases. The same was observed for moderate dependence, and for BADLs and IADLs, the prevalences were approximately 2.06 (95% CI, 1.44–2.95) and 1.62 (95% CI, 1.20–2.19), respectively.
Of particular relevance are chronic diseases, such as other mental illnesses and stroke, as they are more disabling conditions that deserve special attention because of their potential to result in severe dependence. Both situations expose the extent to which chronic diseases can affect skills that involve cognitive capacity with regard to the intentionality of performing motor activities and decision-making for autonomy and independence.
Chronic diseases significantly affect the lives of the elderly. The implications of functional decline from the simultaneous occurrence of chronic diseases may be related to the emerging concept of treatment burden, as elderly individuals with multiple chronic diseases are more likely to use several healthcare providers simultaneously and undergo complex treatments than those without multiple chronic diseases31. Discriminating the association between chronic diseases and the state of dependence described in this study reveals the urgency in prioritizing primary health actions, aiming to maintain the functional capacity of this population for as long as possible, corroborating the perspective of the concept of healthy aging32.
Mental alterations with cognitive impairment increase the risk of severe disability with little chance of recovery, further increasing the possibility of death, with a small difference between sexes. In the presence of cognitive impairment, few disability recoveries are observed, especially in severe disabilities, regardless of the presence or absence of another chronic disease33.
These findings corroborate the argument for improving preventive care with special attention to the strong association between functionality and cognition and with greater attention paid to those with cognitive impairment. It is necessary to conduct large cohort studies to better understand the association among population aging, dementia, depression, and disability34,35.
The findings of this study demonstrate that cognitive impairment is the most disabling condition, confirming its importance as a primary determinant of disability. Thus, preventive care should be a priority for the elderly at greater risk of loss of functionality from cognitive impairment, using recognition of physical capacity status, which may result in an opportunity for earlier intervention that would delay the onset of significant disability, preventing the progression of functional impairment12,33,36.
When analyzing the condition of severe dependence for both activities studied (BADLs and IADLs), an inversion of the probabilities of higher values of the factors associated with the occurrence of the severe outcome is obtained compared with the moderate dependence; that is, the chronic disease of the stroke type appears with greater probabilities, with other mental illnesses soon after.
In this study, stroke demonstrated how impactful its occurrence was for an unfavorable outcome both for severe dependence on BADLs and IADLs, overcoming for these stratum situations that, although also harmful, similar with other mental illnesses, translate into evidence of its burden in the development of severe dependence in both activities.
Globally, elevated systolic blood pressure is the single greatest risk factor for stroke (contributing 79.6 million disability-adjusted life years [DALYs] (7.7–90.8) or 55.5% (48.2–62.0) of the total DALY of stroke)37. Hypertension is a multifactorial chronic disease that is related to different outcomes, among which stroke is recognized as one of the main outcomes38. The Global Burden of Disease (GBD) estimates that stroke overload in the elderly is expected to increase by 44% from 2004 to 203039.
In 2019, 89% of the stroke burden was related to developing countries. In addition, more than 12.2 million new stroke cases are reported annually. Globally, one in four people aged > 25 years experiences a stroke in their lifetime. More than 143 million years of healthy life is lost annually due to stroke, death, and disability40.
In developing countries, acute stroke requires greater investment in specialized units for better management, including rehabilitation with physiotherapy and speech and occupational therapies, in addition to counseling, with the aim of reducing deaths, disabilities, and the need for long-term institutional care41.
In this study, depression was highlighted as a factor significantly associated with moderate dependence in IADLs. Assessing the degree of dependence better distinguishes the reality of the functional decline experienced by the elderly, whose increase is related to higher rates of depression and decreased life satisfaction42,43.
In population studies, important cognitive impairments, such as depression, dementia, and Alzheimer’s disease, contribute to the occurrence of disability and different states of functional dependence, with an emphasis on dependence on instrumental activities44,45.
Gill et al. observed that in the trajectory of mental disability, it was possible to verify that among individuals with advanced stages of dementia, depression, and/or cognitive impairment, approximately 67.9% of the elderly had persistent severe disability46. Another study demonstrated that the elderly with mental problems and cognitive deficits immediately transitioned to a disabled status and later died47.
The elderly population needs screening mechanisms for the discovery of mild cognitive impairment and should be considered a “high-risk” population worthy of greater attention, in view of what has been demonstrated and the rapid progression of cognitive impairment to disability48,2.
Kidney failure was highlighted in association with moderate dependence on IADLs, emphasizing that the implications of this chronic disease for dependence are intrinsically associated with the routine activities performed by the patient, considering that the disease itself has several limitations, which may be related to complications of diabetes, other mental health problems, and stroke. This chronic disease is even more closely related to the outcome of severe dependence on IADLs, reflecting its degree of interference in activities that require greater involvement in both motor and cognitive skills.
However, the prevalence of chronic kidney disease in Brazil remains unclear. More recent population estimates reveal approximately 1.5% of self-reported kidney diseases49. This statistic indicates that the negative effects of chronic kidney disease on independence can be cumulative, causing injuries that increase a person’s suffering, especially when requiring dialysis care, imposing various restrictions and limitations on the patient, requiring the permanent help of others50,51.
Hospitalization, incapacity to work, and loss of independent living are more common among patients with chronic kidney failure than in the general population52. Multimorbidity requires effective management beyond kidney failure itself53,54.
In the condition of severe dependence on BADLs, diabetes advanced as an important condition when the probability for the occurrence of the outcome increased, previously occupied by chronic back problems in moderate dependence. Diabetes in moderately dependent IADLs is probably also related to limitations imposed by the disease. This is because care for the elderly with diabetes requires considerable vigilance and quality monitoring, given the need to use specific medications, with previous blood glucose measurement, balanced dosage, and maintenance of an adequate diet. These can provide the elderly with appropriate living conditions without greater risks of discomfort, such as hypoglycemia, which can precede falls and other complications. In contrast, uncontrolled glycemic control can evolve into systemic problems, including kidney failure and blindness, worsening functional dependence54.
By 2040, diabetes will be the third leading cause of death in Brazil, and hyperglycemia will be the third leading cause of death. According to the GBD 2017 data for diabetes, premature deaths from diabetes considerably increased from 27.4 to 31.6%, disability due to diabetic neuropathy increased from 14.5 to 18.5%, and living with diabetes increased from 4.4 to 5.1%55.
The detection and management of diabetes in the elderly is suboptimal. The prevalence of diabetes (diagnosed and undiagnosed) increases markedly with age, from approximately 2.4% in individuals aged 20–39 years to 21.6% in individuals aged > 65 years39.
Diabetes had the highest risk of incident disability in men (hazard ratio [HR], 3.0; 95% CI, 2.4–3.8) and women (HR, 1.7; 95% CI, 1.3–2.2). Both sexes have a considerable risk of disability47.
In a Peruvian study, the prevalences of severe functional dependence in patients with and without diabetes were 7.1% (95% CI, 5.5–9.0%) and 5.8 (95% CI, 5.0–6.6%), respectively. Similarly, the prevalences of moderate functional dependence were 15.6% (95% CI, 12.7–18.9%) and 12.4% (95% CI, 11.5–13.3%) in patients with and without diabetes, respectively. Thus, 22.6% (95% CI, 19.4–26.2%) of patients with diabetes had some degree of functional dependence compared with 18.1% (95% CI, 16.9–19.4%) of patients without diabetes56.
Chronic diseases, such as COPD, directly interfere with IADL development, as instrumental activities have several characteristics, in addition to requiring greater ability to solve more complex situations from a cognitive point of view. This, in unsuccessful situations, can lead to anxiety, with respiratory repercussions, and requires cardiorespiratory conditioning that is compatible with the degree of demand of the activity, such as locomotion on different planes, climbing obstacles, and balance, which demands an efficient respiratory system from the elderly, capable of initiating and finishing activities, which are rarely observed in cases of COPD, even mild cases.
COPD is the third leading cause of death worldwide, causing 3.23 million deaths in 2019. Nearly 90% of COPD deaths in individuals aged < 70 years occur in low- and middle-income countries57.
Studies have presented results that explicitly state that the greater the impairment of lung function, the more impaired the functional capacity of individuals with COPD. The greater the degree of lung capacity impairment, the greater its influence on an individual’s functional capacity58–60.
More than three-quarters of the global COPD cases occur in low- and middle-income countries. Addressing this chronic disease is a major and growing challenge for healthcare systems in these locations. In the absence of population-wide efforts and health system reforms in these countries, where several countries have limited resources, achieving a substantial reduction in the global burden of COPD may remain difficult61.
Brazilian estimates indicate that respiratory diseases, such as asthma and COPD, have a higher prevalence than other chronic respiratory diseases62,63, which is similar to the data from other countries57,64.
In this study, RA remained in the same order of importance when comparing moderate and severe dependence status for BADLs. The same did not occur for IADL outcomes.
RA is a chronic systemic autoimmune condition that primarily affects synovial joints, causing inflammation (synovitis), joint erosion, and cartilage damage. This results in a reduced functional status and disability in several patients. RA can also manifest as an extra-articular disease that affects most organs in the body, leading to higher mortality and morbidity65.
RA is one of the main contributors to functional dependence and loss of independence in the elderly, causing difficulties in maintaining their activities of daily living66. Data from the GBD Project identify common causes of years of healthy life lost due to disability in individuals aged > 60 years and identify osteoarthritis as one of the 10 most relevant causes of disability in this population67.
Diseases such as RA have been described as being diseases of long-term addiction, reflecting the low lethality and high disabling effect, with worse scenarios for elderly women with diabetes as well47,68.
Owing to the health emergency in the last 3 years, it is important to mention the synergistic interaction between chronic diseases, which was moderately evidenced in the factor analysis in the present study, which, with the emergence of coronavirus disease 2019 (COVID-19), worsened in the presence of chronic non-communicable diseases (CNCDs). In one of the first published meta-analyses on this subject, Wang et al. (69)found a significant increase in the risk of worsening the new coronavirus disease among patients with multimorbidities. Studies have identified hypertension, COPD, and cardiovascular and cerebrovascular diseases as independent risk factors for COVID-1970.
One of the first evidence identified in the pandemic was that the magnitude and severity of cases were intensified because of other pre-existing chronic diseases. As a syndemic, COVID-19 interacts, aggravates, and is aggravated by CNCDs and existing social conditions71.
Economically underserved populations and ethnic minority groups have higher rates of nearly all clinical risk factors that increase the severity and mortality of COVID-19 (71). A meta-analysis study revealed the high prevalence of multimorbidities among fatal and severe cases resulting from COVID-1972.
Although the biological repercussions of the disease are not fully understood, respiratory, neurological, musculoskeletal, and mental health problems have affected infected individuals. Thus, health systems should expand and facilitate access to specialized outpatient and physiotherapy services and psychosocial care networks. Additionally, it is important to integrate these services with primary health care to guarantee integrated and longitudinal care73.
Limitations
The study data were almost entirely self-reported; therefore, there was a potential information bias. Nevertheless, the use of self-reported information has been widely used and previously validated in relation to studies with laboratory tests and objective examinations. Moreover, in population-based studies, it has been widely used to provide information about the severity and type of limitations experienced in different situations and contexts with a good degree of reliability74–77.
Strengths
This is one of the rare studies in an elderly population in a developing country that examined the particularities of the relationship between chronic diseases in isolation and multimorbidity in relation to the outcome status of the severity of functional dependence, making it possible to analyze this outcome in a more detailed and gradual manner. Thus, considering moderate and severe dependence and comparing it with elderly individuals without dependence, it is possible to establish dependence gradients and associate them with the demands and rehabilitation actions to be offered to these vulnerable populations, which require more specific care.
In view of this, the option for measuring functional dependence, characterizing it as mild, moderate, and severe, aimed to better express the functional reality of the elderly, subject providing information, and opting for a sensitive but not less specific criterion.