Marilyn L. Moy

A pilot study of an Internet walking program and pedometer in COPD

BACKGROUND Higher levels of physical activity are associated with better functional status, fewer hospital admissions, and lower mortality. In this pilot study, we examined the feasibility and safety of a novel program that combines a pedometer with a website to increase walking. METHODS 27 persons with stable COPD wore the Omron HJ-720ITC pedometer and used the website for 90 days. They uploaded step-count data to the study server using their home computer and received an email each week with their individualized step-count goal. The website provided step-count feedback, education, and motivational content. Subjects participated in a monthly semi-structured interview by telephone. Subjects reported changes in medical condition by telephone or on the website. Paired T-tests assessed change in daily step counts. RESULTS Subjects were males, mean age 72 ± 8 years, with moderate COPD, FEV(1) 1.57 ± 0.48 L (55 ± 16% predicted). 87% and 65% reported no problems using the pedometer and website, respectively. At month 3, 96% reported it was true that they knew their step count goal every day, and 52% reported that they were able to reach their goal. 95% of participants said they would recommend the walking program to another person with COPD. Eight subjects experienced breathing problems unrelated to the intervention. In 24 subjects with step counts at baseline and month 3, there was a significant increase of 1263 steps per day (approximately 1.0 km), p = 0.0054. CONCLUSIONS The use of a website and pedometer was feasible and safe, and persons increased their daily walking.

Free-Living Physical Activity in COPD: Assessment with Accelerometer and Activity Checklist

To assess physical activity and disability in chronic obstructive pulmonary disease (COPD), we evaluated the use of an accelerometer and checklist to measure free-living physical activity. Seventeen males with stable COPD completed a daily activity checklist for 14 days. Ten subjects concurrently wore an Actiped accelerometer (FitSense, Southborough, Massachussetts) that records steps per day. Regression models assessed relationships between steps per day, number of daily checklist activities performed, and clinical measures of COPD status. The average steps per day ranged from 406 to 4,856. The median intrasubject coefficient of variation for steps per day was 0.52 (interquartile range [IQR] 0.41-0.58) and for number of daily checklist activities performed was 0.28 (IQR 0.22-0.32). A higher number of steps per day was associated with a greater distance walked on the 6-minute walk test and better health-related quality of life. A higher number of daily checklist activities performed was associated with a higher force expiratory volume in 1 s percent predicted and lowerbody mass index, airflow obstruction, dyspnea, exercise capacity (BODE) index. Prospectively measuring free-living physical activity in COPD using an unobtrusive accelerometer and simple activity checklist is feasible. Low intrasubject variation was found in free-living physical activity, which is significantly associated with clinical measures of COPD status.

Using hierarchical clustering methods to classify motor activities of COPD patients from wearable sensor data

BackgroundAdvances in miniature sensor technology have led to the development of wearable systems that allow one to monitor motor activities in the field. A variety of classifiers have been proposed in the past, but little has been done toward developing systematic approaches to assess the feasibility of discriminating the motor tasks of interest and to guide the choice of the classifier architecture.MethodsA technique is introduced to address this problem according to a hierarchical framework and its use is demonstrated for the application of detecting motor activities in patients with chronic obstructive pulmonary disease (COPD) undergoing pulmonary rehabilitation. Accelerometers were used to collect data for 10 different classes of activity. Features were extracted to capture essential properties of the data set and reduce the dimensionality of the problem at hand. Cluster measures were utilized to find natural groupings in the data set and then construct a hierarchy of the relationships between clusters to guide the process of merging clusters that are too similar to distinguish reliably. It provides a means to assess whether the benefits of merging for performance of a classifier outweigh the loss of resolution incurred through merging.ResultsAnalysis of the COPD data set demonstrated that motor tasks related to ambulation can be reliably discriminated from tasks performed in a seated position with the legs in motion or stationary using two features derived from one accelerometer. Classifying motor tasks within the category of activities related to ambulation requires more advanced techniques. While in certain cases all the tasks could be accurately classified, in others merging clusters associated with different motor tasks was necessary. When merging clusters, it was found that the proposed method could lead to more than 12% improvement in classifier accuracy while retaining resolution of 4 tasks.ConclusionHierarchical clustering methods are relevant to developing classifiers of motor activities from data recorded using wearable systems. They allow users to assess feasibility of a classification problem and choose architectures that maximize accuracy. By relying on this approach, the clinical importance of discriminating motor tasks can be easily taken into consideration while designing the classifier.

Daily Step Count Predicts Acute Exacerbations in a US Cohort with COPD

Background COPD is characterized by variability in exercise capacity and physical activity (PA), and acute exacerbations (AEs). Little is known about the relationship between daily step count, a direct measure of PA, and the risk of AEs, including hospitalizations. Methods In an observational cohort study of 169 persons with COPD, we directly assessed PA with the StepWatch Activity Monitor, an ankle-worn accelerometer that measures daily step count. We also assessed exercise capacity with the 6-minute walk test (6MWT) and patient-reported PA with the St. Georges Respiratory Questionnaire Activity Score (SGRQ-AS). AEs and COPD-related hospitalizations were assessed and validated prospectively over a median of 16 months. Results Mean daily step count was 5804±3141 steps. Over 209 person-years of observation, there were 263 AEs (incidence rate 1.3±1.6 per person-year) and 116 COPD-related hospitalizations (incidence rate 0.56±1.09 per person-year). Adjusting for FEV1 % predicted and prednisone use for AE in previous year, for each 1000 fewer steps per day walked at baseline, there was an increased rate of AEs (rate ratio 1.07; 95%CI = 1.003–1.15) and COPD-related hospitalizations (rate ratio 1.24; 95%CI = 1.08–1.42). There was a significant linear trend of decreasing daily step count by quartiles and increasing rate ratios for AEs (P = 0.008) and COPD-related hospitalizations (P = 0.003). Each 30-meter decrease in 6MWT distance was associated with an increased rate ratio of 1.07 (95%CI = 1.01–1.14) for AEs and 1.18 (95%CI = 1.07–1.30) for COPD-related hospitalizations. Worsening of SGRQ-AS by 4 points was associated with an increased rate ratio of 1.05 (95%CI = 1.01–1.09) for AEs and 1.10 (95%CI = 1.02–1.17) for COPD-related hospitalizations. Conclusions Lower daily step count, lower 6MWT distance, and worse SGRQ-AS predict future AEs and COPD–related hospitalizations, independent of pulmonary function and previous AE history. These results support the importance of assessing PA in patients with COPD, and provide the rationale to promote PA as part of exacerbation-prevention strategies.

Use of pedometer and Internet-mediated walking program in patients with chronic obstructive pulmonary disease

We evaluated an Internet-mediated, pedometer-based program to promote walking in chronic obstructive pulmonary disease (COPD). First, we assessed the accuracy of the Omron HJ-720ITC pedometer (OMRON Healthcare, Inc; Bannockburn, Illinois) in 51 persons with COPD. The Bland-Altman plot showed a median difference of 3 steps (5th and 95th quintiles, -8.0 and 145.0, respectively). We calculated percent difference = ([manual - Omron step counts]/manual step counts) x 100. Variability in percent difference occurred at the lowest usual walking speeds. At speeds <or= 0.94 m/s, the mean +/- standard deviation percent difference was 14 +/- 26%. Nevertheless, the Omron captured >80% of the manual step counts in 20 of the 23 persons with walking speed <or= 0.94 m/s. Second, we examined step counts in 24 persons with COPD who used the Omron and an Internet-mediated, 16-week walking program. At baseline, participants with COPD walked an average of 3429 +/- 1502 steps per day. Sixteen participants completed the program with an average increase in daily step count of 988 +/- 1048 steps (p = 0.002). The Omron is accurate in persons with COPD with usual walking speeds > 0.94 m/s. Accuracy is more variable at lower speeds, but the Omron captures more than 80% of manual step counts in most persons.In this preliminary study, an Internet-mediated walking program using the Omron significantly increased step counts in COPD.

An Internet-Mediated Pedometer-Based Program Improves Health-Related Quality-of-Life Domains and Daily Step Counts in COPD

BACKGROUND Low levels of physical activity (PA) are associated with poor outcomes in people with COPD. Interventions to increase PA could improve outcomes. METHODS We tested the efficacy of a novel Internet-mediated, pedometer-based exercise intervention. Veterans with COPD (N = 239) were randomized in a 2:1 ratio to the (1) intervention group (Omron HJ-720 ITC pedometer and Internet-mediated program) or (2) wait-list control group (pedometer). The primary outcome was health-related quality of life (HRQL), assessed by the St. Georges Respiratory Questionnaire (SGRQ), at 4 months. We examined the SGRQ total score (SGRQ-TS) and three domain scores: Symptoms, Activities, and Impact. The secondary outcome was daily step counts. Linear regression models assessed the effect of intervention on outcomes. RESULTS Participants had a mean age of 67 ± 9 years, and 94% were men. There was no significant between-group difference in mean 4-month SGRQ-TS (2.3 units, P = .14). Nevertheless, a significantly greater proportion of intervention participants than control subjects had at least a 4-unit improvement in SGRQ-TS, the minimum clinically important difference (53% vs 39%, respectively, P = .05). For domain scores, the intervention group had a lower (reflecting better HRQL) mean than the control group by 4.6 units for Symptoms (P = .046) and by 3.3 units for Impact (P = .049). There was no significant difference in Activities score between the two groups. Compared with the control subjects, intervention participants walked 779 more steps per day at 4 months (P = .005). CONCLUSIONS An Internet-mediated, pedometer-based walking program can improve domains of HRQL and daily step counts at 4 months in people with COPD. TRIAL REGISTRY Clinical Trials.gov; No.: NCT01102777; URL: www.clinicaltrials.gov.

Daily step counts in a US cohort with COPD

BACKGROUND Baseline values for daily step counts in US adults with COPD and knowledge of its accurate measurement, natural change over time, and independent relationships with measures of COPD severity are limited. METHODS 127 persons with stable COPD wore the StepWatch Activity Monitor (SAM) for 14 days, and 102 of them wore it a median 3.9 months later. SAM counts were compared to manual counts in the clinic. We assessed change over time, the effect of season, and relationships with forced expiratory volume in 1 s (FEV(1)) % predicted, 6-min walk test (6MWT) distance, the modified Medical Research Council (MMRC) dyspnea score, and the St. Georges Respiratory Questionnaire Total Score (SGRQ-TS). RESULTS 98% of subjects were males, with mean age 71 ± 8 years and FEV(1) 1.48 ± 0.54 L (52 ± 19% predicted). All 4 GOLD stages were represented, with the most subjects in GOLD II (44%) and GOLD III (37%). The SAM had >90% accuracy in 99% of subjects. Average step count was 5680 steps/day, which decreased with increasing GOLD stage (p = 0.0046). Subjects walked 645 fewer steps/day at follow-up, which was partly explained by season of monitoring (p = 0.013). In a multivariate model, FEV(1) % predicted, 6MWT distance and MMRC score were weakly associated with daily step counts, while SGRQ-TS was not. CONCLUSIONS These findings will aid the design of future studies using daily step counts in COPD. Accurately measured, daily step counts decline over time partly due to season and capture unique information about COPD status.

Multivariate models of determinants of health-related quality of life in severe chronic obstructive pulmonary disease

Persons with severe chronic obstructive pulmonary disease (COPD) and similar levels of forced expiratory volume in 1 second (FEV(1)), exercise capacity, and dyspnea have a wide range of health-related quality of life (HRQL). We identified the independent determinants of HRQL in persons with COPD. Comprehensive assessments of physiological, psychosocial, and clinical variables from the National Emphysema Treatment Trial were used. HRQL was assessed by the Medical Outcomes Study 36-Item Short Form Physical Component Summary (PCS) and Mental Component Summary (MCS) scores and the St. Georges Respiratory Questionnaire total score (SGRQ-TS). In multivariate linear regression models, exercise capacity, dyspnea, age, single-breath diffusing capacity of the lung for carbon monoxide percent predicted, and self-report of being disabled were significant determinants of PCS score. Dyspnea, depression, antidepressant use, daytime sleepiness, and education were significant determinants of MCS score. Prior participation in pulmonary rehabilitation, supplemental oxygen use, and oral corticosteroid use were significant determinants of SGRQ-TS. Although FEV(1), 6-minute walk test distance, and dyspnea significantly correlated with HRQL, their effects on HRQL were reduced when other variables were considered. Greater exercise capacity, prior participation in pulmonary rehabilitation, and use of supplemental oxygen were significantly associated with better HRQL. Self-perception of being disabled, (Abstract continued) depression, dyspnea, oral corticosteroid use, and daytime sleepiness were associated with worse HRQL. To optimize HRQL, clinicians should pay attention to a number of clinical and physiological factors.

An Index of Daily Step Count and Systemic Inflammation Predicts Clinical Outcomes in Chronic Obstructive Pulmonary Disease

BACKGROUND Identification of persons with chronic obstructive pulmonary disease (COPD) at risk for acute exacerbations (AEs) targets them for close monitoring. OBJECTIVES We examined the ability of a novel index combining physical activity and systemic inflammation to identify persons at risk for AEs. METHODS In an observational cohort study of 167 persons with COPD, we assessed daily step count, a direct measure of physical activity, with the StepWatch Activity Monitor and measured plasma C-reactive protein (CRP) and IL-6 levels. AEs and COPD-related hospitalizations were assessed prospectively over a median of 16 months. Predictors of AEs and COPD-related hospitalizations were assessed using negative binomial models. MEASUREMENTS AND MAIN RESULTS Median daily step count was 5,203 steps (interquartile range, 3,627-7,024). Subjects with daily step count ≤ 5,203 and CRP > 3 mg/l had an increased rate of AEs (rate ratio [RR], 2.06; 95% confidence interval [CI], 1.30-3.27) and COPD-related hospitalizations (RR, 3.51; 95% CI, 1.73-7.11) compared with subjects with daily step count > 5,203 and CRP ≤ 3 mg/l, adjusting for FEV1% predicted and prednisone use for AE in the previous year. Similarly, subjects with daily step count ≤ 5,203 and IL-6 > 2 pg/ml had an increased rate of AEs (RR, 2.04; 95% CI, 1.14-3.63) and COPD-related hospitalizations (RR, 4.27; 95% CI, 1.56-11.7) compared with subjects with daily step count > 5,203 and IL-6 ≤ 2 pg/ml. CONCLUSIONS An index combining daily step count and systemic inflammation can predict AEs and COPD-related hospitalizations. A validation study in a separate cohort is needed to confirm the utility of the proposed index as a clinical tool to risk stratify persons with COPD.

Daily Step Count Is Associated With Plasma C-Reactive Protein and IL-6 in a US Cohort With COPD

BACKGROUND Physical activity is an important clinical marker of disease status in COPD. COPD is also characterized by low-grade systemic inflammation. However, the relationship between physical activity and systemic inflammation in COPD is unclear. METHODS We monitored daily step count, a directly measured physical activity, using the StepWatch Activity Monitor, an ankle-worn accelerometer, in 171 people with stable COPD. Exercise capacity was assessed with the 6-min walk test (6MWT). We measured plasma C-reactive protein (CRP) and IL-6 levels. Linear regression models examined the cross-sectional associations of daily step count and 6MWT distance with CRP and IL-6 levels. RESULTS Subjects had a mean age 72±8 years and mean FEV1 1.5±0.57 L (54±20% predicted). Median daily step count was 5,203 (interquartile range [IQR], 3,627-7,024], CRP level was 2.4 mg/L (IQR, 1.2-5.0), and IL-6 level was 2.9 pg/mL (IQR, 2.0-5.1). Each 1,000-step increase in daily step count was associated with a 0.94 mg/L and 0.96 pg/mL decrease in CRP (P=.020) and IL-6 (P=.044) levels, respectively, adjusting for age, FEV1 % predicted, pack-years smoked, cardiac disease, current statin use, history of acute exacerbations, and season. There was a significant linear trend of increasing daily step count by quartiles and decreasing CRP (P=.0007) and IL-6 (P=.023) levels. Higher 6MWT distance was also significantly associated with lower CRP and IL-6 values. CONCLUSION People with COPD who walked the most had the lowest plasma CRP and IL-6 levels. These results provide the conceptual basis to study whether an intervention to promote walking will reduce systemic inflammation in people with COPD.