Correlates of physical activity in chronic obstructive pulmonary disease.

BACKGROUND: Physical activity is a key dimension of functional status in people with chronic obstructive pulmonary disease (COPD), and the central target of interventions in this group. OBJECTIVES: To determine the relationships among functional performance measured as physical activity, functional capacity, symptom experiences, and health-related quality of life in people with COPD. METHOD: Cross-sectional, descriptive study. Convenience sample of 63 outpatients with COPD studied prior to entry into a pulmonary rehabilitation program. RESULTS: Daily physical activity, as measured by an accelerometer, was strongly associated with maximal distance walked during a 6-minute walk test (r = .60, p < .00), level of airway obstruction (r = .37, p < .01), walking self-efficacy (r = .27, p < .05), and physical health status (r = .40, p < .01). Physical activity was not correlated with self-report of functional status. The only predictor of physical activity was the 6-minute walk test. CONCLUSIONS: Accelerometer measurement of functional performance was most significantly related to walking abilities. This methodology represents a novel approach to measuring an important dimension of functional status not previously well quantified.

Quantitating physical activity in COPD using a triaxial accelerometer.

STUDY OBJECTIVE: To determine the reliability, validity, and stability of a triaxial accelerometer for walking and daily activity measurement in a COPD sample. DESIGN: Cross-sectional, correlational, descriptive design. SETTING: Outpatient pulmonary rehabilitation program in a university-affiliated Veterans Affairs medical center. PARTICIPANTS: Forty-seven outpatients (44 men and 3 women) with stable COPD (FEV(1), 37% predicted; SD, 16%) prior to entry into a pulmonary rehabilitation program. MEASUREMENTS AND RESULTS: Test-retest reliability of a triaxial movement sensor (Tritrac R3D Research Ergometer; Professional Products; Madison, WI) was evaluated in 35 of the 47 subjects during three standardized 6-min walks (intraclass correlation coefficient [rICC] = 0.84). Pearson correlations evaluated accelerometer concurrent validity as a measure of walking (in vector magnitude units), compared to walking distance in all 47 subjects during three sequential 6-min walks (0. 84, 0.85, and 0.95, respectively; p < 0.001). The validity of the accelerometer as a measure of daily activity over 3 full days at home was evaluated in all subjects using Pearson correlations with other indicators of functional capacity. The accelerometer correlated with exercise capacity (maximal 6-min walk, r = 0.74; p < 0.001); level of obstructive disease (FEV(1) percent predicted, r = 0.62; p < 0.001); dyspnea (Functional Status and Dyspnea Questionnaire, dyspnea over the past 30 days, r = - 0.29; p < 0.05); and activity self-efficacy (Activity Self-Efficacy Questionnaire, r = 0.43; p < 0.01); but not with self-report of daily activity (Modified Activity Recall Questionnaire, r = 0.14; not significant). Stability of the accelerometer to measure 3 full days of activity at home was determined by an rICC of 0.69. CONCLUSIONS: This study provides preliminary data suggesting that a triaxial movement sensor is a reliable, valid, and stable measure of walking and daily physical activity in COPD patients. It has the potential to provide more precise measurement of everyday physical functioning in this population than self-report measures currently in use, and measures an important dimension of functional status not previously well-described.

A new self-administered questionnaire to monitor health-related quality of life in patients with COPD. Ambulatory Care Quality Improvement Project (ACQUIP) Investigators.

STUDY OBJECTIVE: To develop and validate a brief, computer-scannable, self-administered questionnaire to monitor health-related quality of life in patients with COPD. The Seattle Obstructive Lung Disease Questionnaire (SOLQ) consists of 29 items measuring four health dimensions: physical function, emotional function, coping skills, and treatment satisfaction. METHODS: A series of studies was performed to assess reliability, validity, and responsiveness. Internal consistency was measured using a cross-sectional survey of 203 COPD patients. Reproducibility was tested over a 4-month interval among 97 patients with self-reported stable conditions. To assess construct validity, SOLQ scales were correlated with corresponding Chronic Respiratory Disease Questionnaire (CRDQ) scales, the COPD Self-Efficacy Scale (CSES), percent predicted FEV1, and 6-min walk test. Treatment satisfaction scores of 920 subjects were correlated with a general measure of patient satisfaction. Baseline and follow-up scores of subjects were compared to assess treatment responsiveness. RESULTS: SOLQ scales were reliable (Cronbach's alpha 0.79 to 0.93, and intraclass correlation coefficients 0.64 to 0.87). Change in SOLQ scores correlated with corresponding CRDQ scales: dyspnea, r=0.42; emotional burden, r=0.49; mastery, r=0.36. Coping skills correlated highly with CSES, r=0.93. Treatment satisfaction correlation was r=0.54. Significant changes occurred in all three scales postintervention. CONCLUSION: The SOLQ is a reliable, valid, and responsive measure of physical and emotional function, coping skills, and treatment satisfaction. Brief, self-administered, and computer scannable, it is useful in monitoring long-term outcomes among large groups of COPD patients.

The safety of transdermal nicotine as an aid to smoking cessation in patients with cardiac disease.

BACKGROUND: Transdermal nicotine therapy is widely used to aid smoking cessation, but there is uncertainty about its safety in patients with cardiac disease. METHODS: In a randomized, double-blind, placebo-controlled trial at 10 Veterans Affairs medical centers, we randomly assigned 584 outpatients (of whom 576 were men) with at least one diagnosis of cardiovascular disease to a 10-week course of transdermal nicotine or placebo as an aid to smoking cessation. The subjects were monitored for a total of 14 weeks for the primary end points of the study (death, myocardial infarction, cardiac arrest, and admission to the hospital due to increased severity of angina, arrhythmia, or congestive heart failure); the secondary end points (admission to the hospital for other reasons and outpatient visits necessitated by increased severity of heart disease); any side effects of therapy; and abstinence from smoking. RESULTS: There were 48 primary and 78 secondary end points noted in a total of 95 subjects. At least one of the primary end points was reached by 5.4 percent of the subjects in the nicotine group and 7.9 percent of the subjects in the placebo group (difference, 2.5 percent; 95 percent confidence interval, -1.6 to 6.5 percent; P=0.23). In the nicotine group, 11.9 percent of the subjects had at least one of the secondary end points, as compared with 9.7 percent in the placebo group (difference, 2.2 percent; 95 percent confidence interval, -2.2 to 7.4 percent; P= 0.37). After 14 weeks the rate of abstinence from smoking was 21 percent in the nicotine group, as compared with 9 percent in the placebo group (P=0.001), but after 24 weeks the abstinence rates were not significantly different (14 percent vs. 11 percent, P= 0.67). CONCLUSIONS: Transdermal nicotine does not cause a significant increase in cardiovascular events in high-risk outpatients with cardiac disease. However, the efficacy of transdermal nicotine as an aid to smoking cessation in such patients is limited and may not be sustained over time.