Frailty in people with COPD, using the National Health and Nutrition Evaluation Survey dataset (2003–2006)

Abstract

Background

Little is known about frailty in people with chronic obstructive pulmonary disease (COPD). The purposes of this study were to describe frailty, to identify, which demographic and clinical characteristics contributed to frailty, and to examine the relationship between frailty and health-related outcomes in people with COPD.

Methods

This was a secondary cross-sectional study, using data from the National Health and Nutrition Evaluation Survey. The frailty index and outcome measures were derived primarily from survey responses.

Results

The prevalence of frailty was 57.8%. Multivariate logistic regression showed that individuals with COPD who had self-reported shortness of breath and comorbid diabetes were more likely to be frail than those who did not. Frail people tended to have a greater number of disabilities.

Conclusions

The findings support the importance of frailty in the COPD population. Further study is needed to understand frailty in people with COPD, using objective measures for criteria of frailty.

Introduction

Frailty is associated with the decline of physiologic reserves in multiple systems and the inability to respond to stressful insults.¹ Evidence suggests that frailty contributes to falls, disability, and mortality in the general population of older adults.² Less is known about frailty in people with chronic diseases such as chronic obstructive pulmonary disease (COPD). People with COPD experience marked deficits in muscle strength and mass³ and impaired functional status,⁴ which places them at risk for frailty. No studies to date have described frailty in detail from the viewpoint of people who are living with COPD, although frailty has been shown to have a strong association with COPD as a comorbidity.5, 6, 7

Absent a precise definition or measure of frailty, the condition has been generally viewed in two ways.⁸ One view focuses on frailty's physical aspect, such as the phenotype of frailty introduced by Fried.² The other view defines frailty as a condition that is characterized by multidimensional deficits over time.⁹ For example, Gobbens et al¹⁰ define frailty as “a dynamic state affecting an individual who experiences losses in one or more domains of human functioning (physical, psychological, and social)” (p. 176). It is caused by a range of variables, and increases the risk of adverse outcome. Their definition emphasizes the dynamic nature and multifactorial aspects of frailty. Based on the several analyses of frailty that have been conducted,¹¹ most researchers now agree that the concept of frailty should be multidimensional; it should account for the interrelationship of individual factors (i.e., physical and psychological); and it should acknowledge a person's individual context. Gobben et al's definition incorporates these dimensions. Although several conceptual frameworks for frailty have been advanced,¹² we used Gobbens et al's⁹ frailty model to guide our research (Fig. 1), because it is consistent with our understanding of the phenomenon. In addition to describing a distinct relationship between frailty and adverse outcomes, this model illustrates how frailty and adverse outcomes can be affected by multiple personal characteristics.

Studies have described the factors that contribute to frailty in older people.¹³ Although most studies have used different conceptual frameworks and definitions of frailty, several factors have emerged as significant contributors to the condition. Older age,2, 5, 6, 14, 15, 16 particularly in people aged 85 and older¹⁶; female gender; and race, being an African American, have been related to frailty.2, 6, 16, 17 A lower level of education,2, 5, 15, 17 lower income,2, 6, 18 and poorer health perception have also been associated with frailty.2, 14, 15, 19 Chronic diseases, such as COPD, diabetes, peripheral vascular disease, heart failure, and osteoarthritis, and multimorbidity have been significantly associated with frailty.2, 14, 15, 17, 18, 19 Strawbridge et al¹⁹ and Rome-Ortuno et al¹⁵ found that frail people tended to have more symptoms.

Frailty in the general population has been associated with health-related outcomes. Frail individuals had higher rates of disability than those who were not frail.2, 16, 20 Frailty was significantly associated with impairment in activities of daily living (ADL) and instrumental activities of daily living (IADL) disability.2, 14, 15, 20 Furthermore, one cohort study²¹ found that frail people had a significantly higher risk of developing new-onset dependency for ADL than non-frail people. Frail people were more likely to have visits to the emergency department, admission to the hospital, and more contact with physicians.14, 15 The age-adjusted odds ratio for mortality has been shown to be 4.8 for women and 6.9 for men in a frail group compared with non-frail group.¹⁵

The relationship between frailty and chronic disease is complicated. Research has described frailty from the perspective of people with advanced chronic disease.7, 22, 23 The odds of frailty were substantially higher in people with chronic kidney disease than in those without and frailty was related to the severity of chronic kidney disease.⁷ Cardiovascular disease, particularly congestive heart failure, has been associated with an increased likelihood of frailty.²² In addition, it has been suggested that insulin resistance is associated with frailty.²⁴

Researchers have also reported that one frailty marker, decreased strength, significantly predicted toxicity from cancer treatments, including chemotherapy and radiotherapy, in older people with cancer²⁵ and that preoperative frailty was associated with an increased risk of postoperative complications and length of hospital stay in older patients.²⁶ Death was found to be progressively more prevalent in frail patients with congestive heart disease than in frail people without the disease.²⁷

Chronic obstructive pulmonary disease is an irreversible and progressive disease, and people with COPD will experience intermittent exacerbation, characterized by acute deterioration in chronic dyspnea and functional limitation. As with people who have other advanced chronic diseases, people with COPD are more likely to be frail.5, 6, 7 The current study attempts to better understand frailty in the COPD population, including its contributing factors and outcomes. Its findings will aid the development of a more tailored and effective intervention to delay frailty, thereby improving function and minimizing disability in this population.

The purposes of this study were: (1) to describe frailty, (2) to examine the relative contribution of demographic and clinical characteristics to frailty, and (3) to examine the relationship between frailty and health-related outcomes (e.g., ADL/IADL disability and health care utilization) in people with COPD.