Physical activity and longitudinal change in 6-min walk distance in COPD patients (original) (raw)

2014, Respiratory Medicine

Background: The 6-min walk distance (6MWD) is widely used to evaluate functional capacity in patients with chronic obstructive pulmonary disease (COPD). Aim: To examine predictors for longitudinal change in 6MWD including self-reported physical activity, smoking habits, body composition, exacerbations, comorbidity and lung function. Methods: The cohort included 389 patients aged 44e75 years, with clinically stable COPD in GOLD stages IIeIV. The follow-up time was 3 years. Measurements included 6MWD, spirometry, fat and fat free mass index (FMI and FFMI), and assessment of physical activity, smoking habits, comorbidities and exacerbations by questionnaires. Generalized estimating equations (GEE) regression analyses were used to analyze predictors for the change in 6MWD. Results: There was a reduction in 6MWD from baseline to 3 years for patients in GOLD stages III and IV (B Z À36 m, 95% CI Z À51 to À7, p Z 0.009 and B Z À79 m, CI Z À125 to À20, p Z 0.007). The unadjusted GEE analysis demonstrated that baseline self-reported physical activity level, forced expiratory volume in one second (FEV 1 ), forced vital capacity, FFMI, GOLD stages and age predicted change in 6MWD, but in the adjusted GEE analysis only self-reported physical activity level (p Z 0.001) and FEV 1 (p Z 0.019) predicted change over time.