Claudication Distances, the Walking Impairment Questionnaire, and Muscle Heme-Oxygen Saturation Best Describe the Home Daily Activity of Claudicating Patients With Peripheral Artery Disease

There is increasing interest in daily activity as a relevant index of impairment in patients with peripheral artery disease (PAD). However, correlations with other objective and subjective measures of function in PAD are not known. Ninety-six claudicating patients were recruited. Ankle-brachial index resting and with stress was determined, and patients completed the Walking Impairment Questionnaire (WIQ), a 6-minute walk test (6MWT), and a Gardner treadmill test (GTT) with concurrent near-infrared spectroscopy of gastrocnemius heme-oxygen saturation (Sto2). A wearable accelerometer was used to measure total daily steps. Mean daily activity was 4050 ± 2631 steps (n = 96). Peak walking time (r = 0.385), 6MWT (r = 0.53), and WIQ (speed r = 0.370 and distance r = 0.405) correlated with daily activity (P < .001), whereas resting and stress ankle-brachial index did not (P > .05). Three subanalyses were performed. For 6MWT, patients were grouped into those who stopped to rest and those who did not. For the GTT, fuzzy clustering analysis of time to minimum Sto2 of the more symptomatic leg grouped patients into those who reached an Sto2 minimum before (n = 44; 91 ± 12 seconds) and after (n = 12; 625 ± 76 seconds) 5 minutes. Finally, patients were grouped into those who reported bilateral or unilateral intermittent claudication. Our Results (Table) demonstrate less at-home daily activity and less walking distance on average among patients who stop to rest during the 6MWT, reach a minimum Sto2 before 5 minutes during GTT, or experience bilateral claudication. Furthermore, all patients with a time to minimum Sto2 >5 minutes had >5000 steps daily activity. Walking performance and the WIQ (distance and speed subscales) correlated with daily activity, whereas hemodynamics did not. Optimal measures of functional status in PAD need to be further explored so that PAD impairments can be better understood.TableDaily activity subanalysisCategorical groupsDaily activity, steps6-minute walk distance, metersGardner maximum walk time, secondsAnalysis based on 6MWT Rest(s) during 6MWT (n = 40)2490 ± 453237.8 ± 15211.6 ± 37 No rest during 6MWT (n = 52)4706 ± 372339.9 ± 12416.5 ± 28Analysis based on NIRS measurement during GTT Time to minimum Sto2 > 5 minutes (n = 12)7715 ± 1093367.4 ± 21735.2 ± 62 Time to minimum Sto2 < 5 minutes (n = 44)3286 ± 273256.8 ± 20251.0 ± 37Analysis based on claudication symptoms Unilateral symptoms (n = 42)5135 ± 359328.4 ± 12382.9 ± 28 Bilateral symptoms (n = 54)3341 ± 332297.3 ± 9a291.5 ± 22bGTT, Gardner treadmill test; NIRS, near-infrared spectroscopy; 6MWT, 6-minute walk test; Sto2, tissue heme-oxygen saturation.Group differences are significant at P < .001 in all comparisons except where noted.aP < .05.bP < .01. Open table in a new tab