Association Between Physical Activity and Mortality in Patients With Claudication

Andrew W. Gardner; Odessa Addison; Leslie I. Katzel; Polly S. Montgomery; Steven J. Prior; Monica C. Serra; John D. Sorkin

Disclosures

Med Sci Sports Exerc. 2021;53(4):732-739. 

In This Article

Abstract and Introduction

Abstract

Purpose: This study aimed to determine the association between light-intensity physical activity and the incidence of all-cause and cardiovascular mortality in patients with peripheral artery disease (PAD) limited by claudication followed for up to 18.7 yr.

Methods: A total of 528 patients with PAD and claudication were screened in Baltimore between 1994 and 2002, and 386 were deemed eligible for the study. At baseline, patients were classified into three physical activity groups: 1) physically sedentary, 2) light intensity, and 3) moderate to vigorous intensity based on a questionnaire. All-cause and cardiovascular mortality of patients through December 2014 was determined using the National Death Index and the U.S. Department of Veterans Affairs and the U.S. Department of Defense Suicide Data Repository.

Results: Median survival time was 9.9 yr (interquartile range, 4.9–15.7 yr; range, 0.38–18.7 yr). During follow-up, 257 patients (66.6%) died, consisting of 40/48 (83.3%) from the sedentary group, 135/210 (64.3%) from the light-intensity group, and 82/128 (64.0%) from the moderate- to vigorous-intensity group. For all-cause mortality, light-intensity activity status (hazard ratio [HR] = 0.523, P = 0.0007) and moderate- to vigorous-intensity status (HR = 0.425, P < 0.0001) were significant predictors. During follow-up, 125 patients died because of cardiovascular causes (32.4%), in which light-intensity activity status (HR = 0.511, P = 0.0113) and moderate- to vigorous-intensity activity status (HR = 0.341, P = 0.0003) were significant predictors.

Conclusions: Light-intensity physical activity is associated with nearly 50% lower risk of all-cause and cardiovascular mortality in high-risk patients with PAD and claudication. Furthermore, moderate- to vigorous-intensity physical activity performed regularly is associated with 58% and 66% lower risk of all-cause and cardiovascular mortality, respectively. The survival benefits associated with light-intensity physical activity make it a compelling behavioral intervention that extends beyond improving ambulation.

Introduction

Peripheral artery disease (PAD) is highly prevalent[1,2] and costly,[3,4] and it is associated with increased risk for mortality.[5] PAD affects 12%–22% of Americans over 65 yr of age,[6] and the annual Medicare costs for PAD are $3.9 billion in the United States alone.[3] PAD is a strong prognostic indicator of poor long-term survival,[7] as the relative risks for all-cause and cardiovascular mortality are approximately three times higher in patients with PAD than in individuals without PAD. The prognosis worsens as the severity of the PAD increases; relative risk for all-cause and cardiovascular mortality progressively increases with a decrease in the ankle/brachial index (ABI).[7]

The primary symptom of PAD is claudication, resulting from inadequate blood flow to the exercising musculature. Claudication leads to poor health-related quality of life due to ambulatory dysfunction,[8,9] impaired physical function,[9] and lower physical activity.[10,11] Ambulation is necessary to perform many activities of daily living, and it is not surprising that individuals with PAD and claudication adopt an extremely sedentary lifestyle because of pain with ambulation.[12] Low physical activity contributes to higher mortality risk in patients with PAD. Patients with claudication who regularly performed moderate- to vigorous-intensity physical activities had a lower risk of all-cause mortality than less active patients followed for up to 8.5 yr.[13] In PAD patients who primarily have atypical leg pain symptoms or who are asymptomatic, higher levels of self-reported and monitored physical activity were associated with lower risk of all-cause mortality and a combined measure of cardiovascular events and cardiovascular mortality.[14] Furthermore, in PAD patients defined by an ABI < 0.90, a decrease in the number of blocks walked during the preceding week at baseline was associated with higher risk of ischemic heart disease events.[15] Slow walking speed, a surrogate measure of physical activity, was also associated with greater unadjusted risk of cardiovascular mortality,[16] as well as showing a trend of association with cardiovascular mortality after adjustment for 6-min walk distance.[16] These studies point toward a dose response between lower levels of physical activity and higher risk of mortality and cardiovascular events. However, none have addressed whether benefits are seen with lower-intensity physical activity levels, and whether these benefits are evident in patients exclusively with claudication.

Updated physical activity guidelines for U.S. adults provide compelling evidence for the overall health benefits of performing even low amounts of moderate- to vigorous-intensity physical activity.[17] Adults who engage in only minimal moderate- to vigorous-intensity physical activity have nearly a 20% reduction in risk of all-cause mortality compared with those who are completely inactive.[18] Current guidelines by the American College of Sports Medicine also recommend patients with PAD perform moderate-intensity exercise 3–5 d·wk−1.[19] However, many patients with PAD are not capable of engaging in any moderate- to vigorous-intensity physical activity because of functional limitations imposed by claudication, but nearly all patients can at least perform light-intensity physical activity.[20] It is not clear whether engaging in light-intensity physical activity confers survival benefits that are seen with higher intensities of physical activity in patients with claudication. The current investigation is focused to addresses this knowledge gap.

The primary aim of this study was to determine the association between light-intensity physical activity and the incidence of all-cause and cardiovascular mortality in patients with PAD limited by claudication followed for up to 18.7 yr. We hypothesized that light-intensity physical activity would be associated with lower incidence of all-cause and cardiovascular mortality, independent of ABI and comorbid conditions, and that participating in moderate- to vigorous-intensity physical activity would be associated with even lower incidences.

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