Activity Lowers Death Risk from Peripheral Arterial Disease

CHICAGO, July 6 - Patients with peripheral arterial disease who remain active in daily tasks such as shopping and walking have a third the risk of dying compared with those who are more sedentary.

That's the word from Mary M. McDermott, M.D., of Northwestern here, and colleagues, reporting in the online edition of Circulation.

The investigators followed men and women in their 60s and 70s who had peripheral arterial disease of the lower extremities, and found that those who were the least active in their daily activities had about a 3.5-fold risk for dying compared with the most active group.

"Anything patients with peripheral arterial disease can do in their daily life to be more active may help them live longer," said Dr. McDermott.

The investigators conducted an observational study of 460 men and women, mean age 71.9 (+ 8.4) years who were followed for nearly 5 years.

The participants were interviewed at baseline about their physical activities, including how far they walked (in blocks) each week, and how many flights of stairs they climbed.

In addition to demographic data, the authors collected information on the participants' race, body mass index, hypertension, smoking, comorbidities, total cholesterol, HDL cholesterol, leg symptoms, and ankle-brachial index.

Participants also performed a 6-minute walk test, and 225 of the 460 wore vertical accelerometers for seven days.

At the 57-month follow-up, 134 people in the cohort (29%) had died, including 75 of the 225 (33%) who had worn accelerometers at study initiation.

The investigators found that participants with higher activity levels at baseline on accelerometry had a lower all-cause mortality rate (P for trend = 0.003).

Compared with patients in the highest fourth of total activity, those in the lowest fourth had a significantly higher all-cause mortality risk (hazard ratio 3.48, 95% confidence interval 1.23 to 9.87, P=0.019).

In covariate analysis, diabetes and pulmonary disease were also significantly associated with increased risk of death (P= 0.002 and 0.035, respectively).

The least active participants at baseline (among those who wore accelerometers) also had about twice the risk for the combined endpoint of cardiovascular events or cardiovascular mortality as the most active participants (hazard ratio for inactivity, 2.10, 95% CI, 1.06 to 4.14, P=0.033).

Better six-minute walk test performance at baseline was a predictor for lower mortality at followup after adjustment of the data for age, gender, race, ankle-brachial index, BMI, smoking, comorbidities, total cholesterol, HDL, and leg symptoms.

For each standard deviation increment increase of walk test performance, there was a 0.76 drop in hazard ratio for death, the authors found.

The authors noted that their findings were limited by the observational design of the study, and the fact that only about half of the patients at baseline had objective accelerometer measures of activity, due to a shortage of the measurement devices.

They also acknowledged that their findings could have been due to the higher general mortality risk among patients with peripheral arterial disease, although when they conducted an analysis excluding deaths that occurred during the first two years of followup, there was no change in the results, they pointed out.

"Peripheral arterial disease patients with higher levels of physical activity during daily life have reduced mortality rates," Dr. McDermott and colleagues wrote. "Future study with a clinical trial is necessary to determine whether interventions that increase physical activity levels during daily life reduce mortality in patients with PAD. In the meantime, the present findings suggest that clinicians should encourage patients with PAD to increase their physical activity during daily life."