Community walking speed, sedentary or lying down time, and mortality in peripheral artery disease

Abstract

We studied whether slower community walking speed and whether greater time spent lying down or sleeping were associated with higher mortality in people with lower extremity peripheral artery disease (PAD). Participants with an ankle-brachial index (ABI) < 0.90 were identified from Chicago medical centers. At baseline, participants reported their usual walking speed outside their home and the number of hours they spent lying down or sleeping per day. Cause of death was adjudicated using death certificates and medical record review. Analyses were adjusted for age, sex, race, comorbidities, ABI, and other confounders. Of 1314 PAD participants, 189 (14.4%) died, including 63 cardiovascular disease (CVD) deaths. Mean follow-up was 34.9 months ± 18.1. Relative to average or normal pace (2-3 miles/hour), slower walking speed was associated with greater CVD mortality: no walking at all: hazard ratio (HR) = 4.17, 95% confidence interval (CI) = 1.46-11.89; casual strolling (0-2 miles/hour): HR = 2.24, 95% CI = 1.16-4.32; brisk or striding (>3 miles/hour): HR = 0.55, 95% CI = 0.07-4.30. These associations were not significant after additional adjustment for the six-minute walk. Relative to sleeping or lying down for 8-9 hours, fewer or greater hours sleeping or lying down were associated with higher CVD mortality: 4-7 hours: HR = 2.08, 95% CI = 1.06-4.05; 10-11 hours: HR = 4.07, 95% CI = 1.86-8.89; ⩾ 12 hours: HR = 3.75, 95% CI = 1.47-9.62. These associations were maintained after adjustment for the six-minute walk. In conclusion, slower walking speed outside the home and less than 8 hours or more than 9 hours lying down per day are potentially modifiable behaviors associated with increased CVD mortality in patients with PAD.

Keywords: cardiovascular mortality; cardiovascular risk factors; intermittent claudication; modifiable behaviors; peripheral artery disease; physical activity; sedentary; six-minute walk test.

Figure 1

Summary of included participants from three observational cohorts. (WALCS, Walking and Leg Circulation Study.)

Figure 2

Associations of participant-reported community-based walking speed with (A) all-cause mortality and (B) cardiovascular disease mortality in peripheral artery disease participants. (Models are adjusted for age, sex, race, BMI, smoking status, comorbidities, study cohort, and ankle–brachial index. *Pairwise p-values based on group comparison with referent: average or normal walking speed.)

Figure 3

Associations of total lying down or sleeping time with (A) all-cause mortality and (B) cardiovascular disease mortality in peripheral artery disease. (Models are adjusted for age, sex, race, BMI, smoking status, comorbidities, study cohort, and ankle–brachial index. *Pairwise p-values based on group comparison with referent: 8–9 hours.)