Prognostic value of variables derived from the six-minute walk test in patients with COPD: Results from the ECLIPSE study

• Published in: Respiratory medicine 2015-09, Vol.109 (9), p.1138-1146
• Main Authors: Andrianopoulos, Vasileios, Wouters, Emiel F.M, Pinto-Plata, Victor M, Vanfleteren, Lowie E.G.W, Bakke, Per S, Franssen, Frits M.E, Agusti, Alvar, MacNee, William, Rennard, Stephen I, Tal-Singer, Ruth, Vogiatzis, Ioannis, Vestbo, Jørgen, Celli, Bartolome R, Spruit, Martijn A
• Format: Article
• Language: English
• Subjects: Adult; Aged; Body mass index; COPD; Exercise physiology; Exercise Test - methods; Exercise testing; Female; Follow-Up Studies; Forced Expiratory Volume - physiology; Health risk assessment; Hospitalization; Hospitalization - statistics & numerical data; Humans; Kaplan-Meier Estimate; Male; Middle Aged; Mortality; Prognosis; Prognostic markers; Prospective Studies; Pulmonary Disease, Chronic Obstructive - diagnosis; Pulmonary Disease, Chronic Obstructive - mortality; Pulmonary Disease, Chronic Obstructive - physiopathology; Pulmonary/Respiratory; Severity of Illness Index; Studies; Vital Capacity - physiology; Walking - physiology
• ISSN: 0954-6111; 1532-3064
• DOI: 10.1016/j.rmed.2015.06.013

Abstract In addition to the six-min walk distance (6 MWD), other six-min walk test (6 MWT) derived variables, such as mean walk-speed (6MWSpeed), 6-min walk-work (6 MWW), distance-saturation product (DSP), exercise-induced oxygen desaturation (EID), and unintended stops may be useful for the prediction of mortality and hospitalization in patients with chronic obstructive pulmonary disease (COPD). We studied the association between 6 MWT-derived variables and mortality as well as hospitalization in COPD patients and compared it with the BODE index. A three-year prospective study (ECLIPSE) to evaluate the prognostic value of 6 MWT-derived variables in 2010 COPD patients. Cox's proportional-hazard regressions were performed to estimate 3-year mortality and hospitalization. During the follow-up, 193 subjects died and 622 were hospitalized. An adjusted Cox's regression model of hazard ratio [HR] for impaired 6 MWT-derived variables was significant referring to: mortality (6 MWD ≤334 m [2.30], 6MWSpeed ≤0.9 m/sec [2.15], 6 MWW ≤20000  m kg [2.17], DSP ≤290 m% [2.70], EID ≤88% [1.75], unintended stops [1.99]; and hospitalization (6 MWW ≤27000  m kg [1.23], EID ≤88% [1.25], BODE index ≥3 points [1.40]; all p ≤ 0.05). The 6 MWT-derived variables have an additional predictive value of mortality in patients with COPD. The 6 MWW, EID and the BODE index refine the prognosis of hospitalization.