Clinical research study
COPD as a Systemic Disease: Impact on Physical Functional Limitations

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Abstract

Purpose

Although chronic obstructive pulmonary disease (COPD) has a major impact on physical health, the specific impact of COPD on physical functional limitations has not been characterized clearly. We aimed to elucidate the physical functional limitations that are directly attributable to COPD compared to a matched referent group without the condition.

Methods

We used the Function, Living, Outcomes, and Work (FLOW) cohort study of adults with COPD (n=1202) and referent subjects matched by age, sex, and race (n=302) to study the impact of COPD on the risk of a broad array of functional limitations using validated measures: lower extremity function (Short Physical Performance Battery [SPPB]), submaximal exercise performance (Six Minute Walk Test [SMWT]), standing balance (Functional Reach Test), skeletal muscle strength (manual muscle testing with dynamometry), and self-reported functional limitation (standardized item battery). Multivariate analysis was used to control for confounding by age, sex, race, height, educational attainment, and cigarette smoking.

Results

COPD was associated with poorer lower extremity function (mean SPPB score decrement for COPD vs referent −1.0 points; 95% CI, −1.25 to −0.73 pts) and less distance walked during the SMWT (−334 feet; 95% CI, −384 to −282 ft). COPD also was associated with weaker muscle strength in every muscle group tested, including both the upper and lower extremities (P<.0001 in all cases) and with a greater risk of self-reported functional limitation (OR 6.4; 95% CI, 3.7 to 10.9).

Conclusions

A broad array of physical functional limitations were specifically attributable to COPD. COPD affects a multitude of body systems remote from the lung.

Section snippets

Overview

The Function, Living, Outcomes, and Work (FLOW) study of COPD is an ongoing prospective cohort study of adult members of an integrated health care delivery system with a physician's diagnosis of COPD and a matched referent group without COPD. At baseline assessment, we conducted structured telephone interviews that ascertained COPD status, health status, self-reported functional limitations, sociodemographic characteristics, and physician-diagnosed comorbidities. Subjects then underwent a

Characteristics of Subjects With and Without COPD

By design, subjects with and without COPD were similar in age, sex, and race-ethnicity (P>.20 in all cases) (Table 1). The prevalence of lifetime smoking was much higher among those with COPD (87%) than in the referent group (48%) (P<.0001). Persons with COPD also had lower social class, as evidenced by lower educational attainment and household income. As expected, pulmonary function was markedly poorer in the COPD group (Table 2). The prevalence of cardiovascular disease (22 vs 3%) and

Discussion

COPD was related to a broad array of physical functional limitations compared to a matched referent group without the disease, including lower extremity functioning, exercise performance, skeletal muscle strength, and self-reported limitation in basic physical actions. These physical functional limitations are directly attributable to COPD, because patients with and without COPD were recruited from the same source population of managed care patients and were matched by age, sex, and race. For

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  • Cited by (0)

    Funded by: NHLBI/NIH R01HL077618.

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