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Background: The six-minute walk test (6MWT) is an established measure of functional exercise capacity associated with clinical prognosis in Chronic Heart Failure (CHF). The aim of this study is to evaluate the employment of tele-accelerometry for the remote assessment of 6MWT in CHF., Methods: 155 patients were subjected to tele-accelerometry in form of monthly 6MWTs in their home surroundings. Accelerometer output included steps/6 min and walking speed. Data was directly transferred via mobile network to the Telemedicine Centre subsequent to test completion. 6MWT distance was measured by hand wheel and steps were counted with a digital hand-counter at baseline (Test 1) and at 12 months follow-up (Test 2)., Results: Accelerometer accuracy was within the 99th percentile. There was a significant correlation between step count, walking speed and measured 6MWT distance (Test 1: steps: r=0.80, P<0.001; Test 2: steps: r=0.90, P<0.001 and Walking Speed Test 1: r=0.80, P<0.001; Walking Speed Test 2: r=0.86, P<0.001). The reproducibility of tele-accelerometry was within 95% margin for all performance parameters, which showed stronger associations to quality of life questionnaire (Short Form - 36) Physical Component Score (PCS) than New York Heart Association (NYHA) functional class., Conclusion: Tele-accelerometry is feasible in patients with CHF and output parameters are indicative of exercise capacity. The benefit of this approach lies in its simplicity under every day circumstances by enabling routine performance testing to assess patients' functional status., (© 2013.)

Background: The prevalence of cardiovascular mortality is high in Chronic Obstructive Pulmonary Disease (COPD) and the identification of clinical parameters to improve risk stratification is of great interest., Objectives: This study aims to assess the predictive strength of daily walking activity on expression of cardiac biomarkers in patients with COPD., Methods: One hundred and five patients with COPD (66.1 ± 8.7 years of age) were prospectively analyzed. Daily walking activity was measured by means of accelerometry. Stepwise multivariate regression analyses were employed with either midregional proatrial natriuretic peptide (MRproANP) or plasma proadrenomedullin (MRproADM) as dependent variables, and age, age-adjusted Charlson score, Modified Medical Research Council Dyspnea Scale (MMRC), Saint Georges Respiratory Questionnaire total score and either total walk, steps per day or fast walk as covariates., Results: Independent predictors of MRproANP included age (p = 0.015) and either total walk or steps per day (both p < 0.0001). Total walk or steps per day were the only independent predictors of MRproADM (p < 0.0001). There was a significant negative correlation between fast walk and MMRC (R = -0.70; p < 0.001) and fast walk was only independently predictive of MRproANP but not MRproADM once MMRC was excluded from the list of covariates (p = 0.023 and p = 0.057, respectively)., Conclusions: Daily walking activity independently predicts levels of circulating MRproANP and MRproADM in stable COPD patients, two prognostic biomarkers of cardiac distress associated with long-term survival upon exacerbation of COPD. Employing activity monitors in the stable state might simplify risk stratification in daily living., (Copyright © 2012 S. Karger AG, Basel.)

Purpose: This study aimed to assess independent predictors of quality of life (QOL) in patients with chronic obstructive pulmonary disease, in particular, to evaluate the relationship between QOL and functional exercise capacity measured with an activity monitor., Methods: Functional exercise capacity was measured with an accelerometer-based walking intensity. QOL was assessed by Short Form-36 and Saint Georges Respiratory Questionnaire. Stepwise multivariate regression analyses were used to identify significant independent predictors of health-related QOL., Results: Daily walking intensity (fast walk) was the only significant independent predictor of the Short Form-36 domains "physical function" (P = 0.002) and "role physical" (P = 0.034). Age and depression were significant independent predictors of the domain "social functioning" (P = 0.035 and P = 0.002, respectively). Age and fast walk were significant independent predictors of the domain "mental health" (P = 0.006 and P = 0.017, respectively). Percent predicted forced expiratory volume in 1 s and fast walk were both significant independent predictors of the domains "general health" (P = 0.04 and P = 0.02, respectively) and "physical component score" (P = 0.038 and P = 0.017, respectively). In terms of the Saint Georges Respiratory Questionnaire, fast walk was a significant independent predictor of "activity score" (P = 0.001), "impact score" (P = 0.022), and "total score" (P = 0.01)., Conclusions: QOL is an important aspect to be integrated into long-term disease management and the assessment of daily walking intensity using accelerometry can provide additional information about the patient's functional status and well-being during a certain period.

Purpose: The purpose of this study was to assess whether daily walking activity is indicative of disease severity in patients with COPD., Methods: Daily activity was measured by accelerometry in 107 COPD: GOLD II (N=28), GOLD III (N=51), and GOLD IV (N=25). Steps per day and times (min/day) spent passively, actively, walking (WLK, 0-5 km/h), and fast walking (FWLK, >5 km/h) were analyzed. Total walking time (TWT) was computed., Results: Times spent WLK (P=0.031), FWLK (P=0.001), TWT (P=0.021), and steps per day (P=0.013) differed significantly between GOLD stages. There was a significant negative correlation between TWK and GOLD stage (R=-0.35; P<0.0001), BODE index (R=-0.58; P<0.0001), and MMRC dyspnea scale (R=-0.65; P<0.0001). Logistic regression analysis showed that both TWT and FWLK were independently and significantly associated with BODE index ≥ 6 (P=0.029 and P=0.040, respectively). The corresponding AUC-value with 95% CI for TWT was 0.80 (95% CI: 0.70 to 0.90) and 0.87 (95% CI: 0.81 to 0.94) for FWLK. The corresponding optimal cut-off value for TWT was 33.3 min/day (sensitivity: 86%; specificity 70%) and FWLK was 0.10 min/day (sensitivity: 93%; specificity 76%)., Conclusion: Daily walking activity, in particular walking intensity, is significant predictor of disease severity in patients with COPD. Objective measures of habitual activity might provide additive value in assessing the likelihood of poor prognosis in this patient cohort., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

This study assesses the accuracy of the Omron HJ-720ITC pedometer at low walking intensities in patients with chronic heart failure. Step accuracy was assessed by visual observation on the treadmill and during free walking at 40, 50, 60, 70, 80 m/min, as well as during self paced walking using the 6 min walk test. A total of ninety-seven patients with heart failure (mean age: 61+/-13, NYHA I, N=30; NYHA II, N=32; NYHA III, N=35) participated in the study. At predefined walking speeds, a statistically significant % error in pedometer accuracy was evident at 60 m/min (p=0.039), and% error increased markedly below this threshold. Highest% error in pedometer accuracy was seen at 40 m/min (mean bias (% error): 28.3+/-9.0%; 95% CI: 21.8-34.7; p<0.001). During self paced walking (6MWT) the absolute% error in pedometer readings was largest in patients with strongest functional limitations and 6 MWT distances <400 m (mean bias (% error): 10.7+/-13.6%; CI 5.6-15.4, p<0.001). The Omron HJ-720ITC pedometer is accurate for monitoring activity in individuals with normal walking behaviour, but seems unsuitable for chronically ill patients characterised by slow walking gaits., (Georg Thieme Verlag KG Stuttgart.New York.)

Background: Distance walked in the 6-minute walk test (6MWT) is an important prognostic parameter used clinically to assess functional status in patients with chronic heart failure (CHF). In this study, we investigated if alternative performance parameters with similar prognostic value can be gained from accelerometers., Methods and Results: Fifty CHF patients (age, 60.9 +/- 14.0 years) were asked to perform a 6MWT while wearing 2 accelerometers and 1 pedometer. Total 6MWT step frequency (SF) and activity counts (VMU) were correlated to 6MWT distance. The accelerometer was highly accurate at quantifying SF (detected vs. observed: r = 0.99; P < .001), whereas the pedometer was unreliable below 50 m/min. VMU increased linearly with walking speed (r = 0.99), and both SF and VMU correlated strongly with 6MWT distance (VMU: r = 0.91; SF: r = 0.87, respectively; P < .001) and each other (r = 0.80, P < .001)., Conclusions: Accelerometers are reliable in measuring physical performance during the 6MWT in CHF patients. Besides the simple acquisition of 6MWT distance currently used for patient assessment, accelerometers provide new data that might be useful to evaluate exercise performance during the 6MWT. This allows for routine assessment of exercise capacity in a home-based setting in the context of telemedicine.

Purpose: The purpose of this study was to use an accelerometer to measure daily walking performance in patients with chronic heart failure (CHF) to investigate if this parameter is a determinant of New York Heart Association class and indicative of maximal and functional exercise capacity., Methods: Fifty patients with CHF were instructed to wear an accelerometer for 7 consecutive days while going about their daily business. Maximal and functional exercise capacity was assessed by cardiopulmonary (VO(2peak)) and 6-minute walk testing, respectively., Results: Patients in New York Heart Association I, II, and III reached an average total walking time (TWT) of 160.6 +/- 35.8 minutes, 133.9 +/- 59.0 minutes, and 76.1 +/- 22.5 minutes per day of which 19%, 19%, and 9% where spent in the fast walking mode (>83 m/minute), respectively. The TWT correlated strongly with VO(2peak) (r = 0.72; P <.001) and 6-minute walk testing distance (r = 0.68; P <.001). The TWT and time spent in fast walking mode were the strongest determinants in discriminating moderate CHF., Conclusion: Daily walking performance is a clear determinant of maximal and functional exercise capacities in patients with CHF. Walking intensity in particular is an independent predictor in discriminating patients with advanced heart failure. Monitoring of daily walking performance might aid in detecting disease progression and improve clinical outcome.