Is asymptomatic peripheral arterial disease associated with walking endurance in patients with COPD?

The Comorbidity of Chronic Obstructive Pulmonary Disease and Peripheral Artery Disease - A Systematic Review

The comorbidity of peripheral arterial disease (PAD) and chronic obstructive pulmonary disease (COPD) is obvious from a clinical point of view, especially as smoking is an important risk factor for both. Another factor connecting these two clinical conditions is chronic inflammation, which plays a crucial role in their pathophysiology. The aim of this study was to present the prevalence of COPD in patients with PAD, as well as the prevalence of PAD in COPD patients confirmed in all patients by two reliable methods: spirometry and ankle-brachial index (ABI), respectively. The MEDLINE, EMBASE, and Cochrane Database of Systematic Reviews were searched to identify the potentially eligible publications from the previous 10 years. The published characteristics of different PAD and COPD populations were analyzed. A database search identified 894 records. Reliable criteria of both COPD and PAD diagnosis were used only in seven publications. The prevalence of PAD among patients with COPD ranged from 8.5 to 81.4%. The severity of the disease and the exclusion of nonsmokers or symptomatic patients from the analyses were important factors affecting this parameter. The prevalence of COPD in patients with PAD was measured reliably only in one study and assessed as 27.2%. The comorbidity of COPD and PAD is a relatively common occurrence. There are very few publications addressing this issue based on reliable diagnostic criteria, especially in the field of PAD. In the case of COPD and PAD patients, spirometry and ABI measurements are worth considering as noninvasive screening tests for COPD and PAD, respectively.

Does peripheral arterial occlusive disease influence muscle strength and exercise capacity in COPD patients?

Background

The pathophysiology of chronic obstructive pulmonary disease (COPD) is complex and understanding of it has been changing in recent years, with regard to its multisystemic manifestations, especially peripheral dysfunction and its influence on intolerance to exercise.

Objectives

To evaluate the relationship between peripheral arterial occlusive disease (PAOD) and peripheral muscle strength and exercise capacity in COPD patients.

Methods

We conducted a cross-sectional study of 35 patients with COPD who were evaluated with the Ankle-Brachial Index, handgrip strength test, 1 repetition maximum (1RM) of knee extensors and flexors, and distance covered in the incremental shuttle walking test (dISWT).

Results

COPD patients with coexisting PAOD had lower dominant handgrip strength test results (33.00 vs. 26.66 kgf, p = 0.02) and worse performance in the dISWT (297.32 vs. 219.41 m, p = 0.02) when compared to the COPD patients without PAOD. Strong correlations were found between the result of the handgrip strength test and both the dISWT (r = 0.78; p < 0.001) and the 1RM/knee extension (r = 0.71; p = 0.03); and also between the dISWT and both the 1RM/knee extension (r = 0.72; p = 0.02) and the 1RM/knee flexion (r = 0.92; p < 0.001). The linear regression model showed that the dISWT variable alone explains 15.3% of the Ankle-Brachial Index result (p = 0.01).

Conclusion

COPD patients with PAOD exhibit reduced muscle strength and lower exercise capacity than COPD patients without PAOD.

Systematic review of the association between exercise tests and patient-reported outcomes in patients with chronic obstructive pulmonary disease

Introduction

Chronic obstructive pulmonary disease (COPD) is an increasingly common cause of death worldwide. Its cardinal symptoms include breathlessness and severely reduced exercise capacity. Several patient-reported outcome (PRO) measures are used to assess health-related quality of life (HRQoL), functional performance, and breathlessness in patients with COPD. Exercise testing is employed to measure functional performance objectively, which is generally believed to impact on overall HRQoL. However, the extent to which commonly used laboratory- and field-based exercise test results correlate with PROs has not been systematically assessed.

Materials and methods

A search of Embase, MedLine, and the Cochrane Library identified primary publications in English that reported data on the correlations (Pearson’s r or Spearman’s ρ) between the outcomes of exercise tests and HRQoL and breathlessness PROs. Studies reporting on the following tests were included: 6-minute walk test (6MWT), 12MWT, incremental and endurance shuttle walk tests, incremental and endurance cycle ergometer tests, and treadmill tests.

Results

Of 3,205 articles screened, 28 were deemed eligible for inclusion. The most commonly reported HRQoL PRO measure was the St George’s Respiratory Questionnaire (13 studies), and the most commonly reported breathlessness PRO measure was the Baseline Dyspnea Index (six studies). The St George’s Respiratory Questionnaire appears to correlate very weakly to moderately with the 6MWT, and breathlessness PROs appear to be moderately to strongly associated with 6MWT outcomes. Across all studies, the 6MWT was the most commonly reported exercise test. Very few publications reporting associations between other exercise tests and PRO measures were found.

Conclusion

This review found evidence to support the association of 6MWT outcomes with HRQoL and breathlessness PROs. There were limited data showing correlations with the outcomes of other exercise tests. Further work is required to examine the associations between these PROs and exercise test outcomes.

Prediction of 6-minute walk performance in patients with peripheral artery disease

BACKGROUND

Peripheral artery disease (PAD) is a highly prevalent disease that impairs walking ability. Walking tests, such as the 6-minute walk test (6MWT) and 4-meter walk test, are commonly used to assess exercise endurance and ambulatory function over a short distance, respectively. The 6MWT performance is predictive of PAD severity and disease outcomes, but it is not feasible in many clinical settings because it requires a long walkway to serve as the test route and lengthens clinic visits. As an alternative, the 4-meter walk test is convenient, inexpensive, and repeatable, but whether it accurately predicts endurance performance in the long-distance 6MWT is not known. The goal of this study was to develop a statistical model to predict 6MWT gait speed from 4-meter walk test results and clinical characteristics among patients with PAD.

METHODS

Measures of 6MWT gait speed were derived from 183 patients with symptomatic PAD who were evaluated at the University of Oklahoma Health Sciences Center (2004-2012). The testing procedures and research personnel remained constant throughout the duration of the study. Independent variables included demographic and clinical information and 4-meter walk test gait speed. Fivefold cross validation and manual backward selection were used for model selection. Adjusted R² and corrected Akaike information criterion were applied to quantify the predictive performance of the regression models.

RESULTS

A total of 183 people (54% male; mean age, 65 [standard deviation (SD), 10] years) with moderate PAD severity (ankle-brachial index [ABI]; mean, 0.72 [SD, 0.24]) performed the walking tests. Participants covered an average distance of 335 (SD, 97) m distance in the 6MWT. The 4-meter walk gait speed, ABI, and dyspnea were independent predictors of 6MWT speed in the multivariate model (adjusted R² = 0.55). The model resulted in 95% prediction interval widths of 30 m for mean and 260 m for individual predicted 6MWT distance measures.

CONCLUSIONS

Slower 4-meter walking speed, lower ABI, and presence of dyspnea all predict slower 6MWT gait speed, which corresponds to shorter 6MWT distance. Prediction of group means is reasonably precise; however, prediction of individual patient 6MWT performance is imprecise relative to between-group differences that are clinically important.