Original Article
Disability, more than multimorbidity, was predictive of mortality among older persons aged 80 years and older

https://doi.org/10.1016/j.jclinepi.2009.09.007Get rights and content

Abstract

Objective

In this study, we evaluate the impact of disability and multimorbidity on the risk of all-cause death in a population of frail older persons living in community.

Study Design and Setting

We analyzed data from the Aging and Longevity Study in the Sirente geographic area, a prospective cohort study that collected data on all subjects aged 80 years and older (n = 364). The main outcome measure was all-cause mortality over 4-year follow-up.

Results

A total of 150 deaths occurred. Sixty-seven subjects (44.6%) died in the nondisabled group compared with 83 subjects (55.3%) in the disabled group (P < 0.01). Thirty-nine subjects (31.7%) died among subjects without multimorbidity compared with 111 subjects (46.0%) with two or more diseases (P < 0.01). When examining the combined effect of multimorbidity and disability, the effect of disability on the risk of death was higher than that of multimorbidity. After adjusting for potential confounders, relative to those without disability and multimorbidity, disabled subjects showed an increased risk of death when multimorbidity was associated (hazard ratio [HR] = 3.91; 95% confidence interval [CI] = 1.53–10.00) and in absence of multimorbidity (HR = 2.36; 95% CI = 0.63–8.83).

Conclusion

Our results show that disability exerts an important influence on mortality, independently of age and other clinical and functional variables.

Introduction

Advancing age is associated with increased vulnerability to chronic health problems. In late years of life, physiological decrements, chronic diseases, and other health problems tend to accumulate and complicate individuals' health status and quality of life.

The presence of multimorbidity, defined as the concomitant presence of multiple diseases in the same individual [1], is a major issue in geriatrics and will have increased importance in the future [2], [3]. The prevalence of multimorbidity increases with age, mostly because of the high frequency of individual chronic conditions in advanced age. Comorbidity affects the progression of concurrent disease [4], [5], [6], decreases quality of life [7], and increases the risk and severity of disability [8], [9] and death [7]. However, the association between multimorbidity and survival in old age is still controversial.

Disability is often considered an interaction between features of the person and features of the context in which the person lives (interaction between disease and environment) [10]. Physical disability in late life results from the combined effect of diseases and physiological alterations related to aging. The impact of these underlying causes is modified by social, economic, and behavioral factors and access to medical care. Although disability itself is an adverse health outcome, it is also a risk factor for other adverse events. Indeed, disability, independent of its causes, may predict subsequent difficulty in instrumental and basic activities of daily living (ADL) [11], [12], and it has been associated with an increased risk of death [13], hospitalization [14], need for long-term care [14], and higher health care expenditures [15].

The transition from a “young” to an “old” population has been followed by an increased prevalence of chronic diseases and functional impairments. In a recent study of 21 family practices in Canada, the prevalence of multimorbidity was higher among elderly than young individuals, and the number of chronic conditions varied from 2.8 in the youngest to 6.4 in the oldest [16]. Understanding the biological, clinical, and environmental factors that facilitate successful aging may represent a new way of limiting disabilities and functional impairments in the extreme confines of life. Octogenarians and nonagenarians are an ideal model to explore biological and nonbiological determinants of aging and longevity. Studies in specific and well-defined geographic areas can further help in interpreting and disentangling all the complex interactions between aging and environment.

Several observational studies have evaluated the impact of multimorbidity and disability on mortality in persons aged 70 years and older [17]. Nonetheless, few previous cohort studies have investigated the interaction between multimorbidity and disability on all-cause mortality in the very old and frail populations. Finally, most epidemiological research and clinical practice are still based on the single-disease paradigm, which may not be appropriate for subjects with overlapping and complex health problems [18].

In the present study, we evaluate the impact of disability and multimorbidity on all-cause mortality in a large population of frail octogenarians and nonagenarians living in community, enrolled in the “Invecchiamento e Longevità nel Sirente” (Aging and Longevity in the Sirente geographic area—ilSIRENTE) Study.

Section snippets

Methods

The ilSIRENTE Study is a prospective cohort study performed in the mountain community living in the Sirente geographic area (L'Aquila, Abruzzo) in Central Italy. This study was designed by the Department of Gerontology, Geriatrics, and Physiatric Medicine of the Catholic University of Sacred Heart (Rome, Italy) and developed by the teaching nursing home, Opera Santa Maria della Pace (Fontecchio, L'Aquila, Italy), in partnership with local administrators and primary care physicians of Sirente

Results

The mean age of 364 subjects participating in the study was 85.9 (SD = 4.9) years, and 244 (67.0%) were women. Characteristics of the study population according to the presence of disability are summarized in Table 1. Compared with disabled participants, those without disability were younger, more likely to live alone with no caregiver support, and had a lower prevalence of cognitive (CPS score) impairment, depressive symptoms, sensory impairments, number of diseases, and medications. Subjects

Discussion

The evaluation of the impact of disability and several co-occurring diseases on survival among frail elderly subjects is an important and intricate issue. In the present study, we explored the association of disability and multimorbidity with 4-year mortality in a sample of community-dwelling subjects aged 80 years or older. Our findings show that disability exerts an important influence on mortality in older adults living in the community, independently of age and other clinical and functional

Acknowledgments

The “Invecchiamento e Longevità nel Sirente” (ilSIRENTE) Study was supported by the “Comunità Montana Sirentina” (Secinaro, L'Aquila, Italy). We thank all the participants for their enthusiasm in participating in the project and their patience during the assessments. We are grateful to all the persons working as volunteers in the “Protezione Civile” and in the Italian Red Cross of Abruzzo Region for their support. We sincerely thank the “Comunità Montana Sirentina” and, in particular, its

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