{
  "abstract": "Background Change in 6-min walk distance (6MWD) over time serves as a measure of change in functional exercise performance. We analysed a large cohort of current or former tobacco smokers over a 5-year period to identify correlates of 6MWD decline.Methods A total of 4734 participants with normal spirometry or spirometric evidence of chronic obstructive pulmonary disease (COPD) who completed a 5-year follow-up in the COPDGene study were included. Baseline and 5-year assessments included 6MWD, spirometry, St. George’s Respiratory Questionnaire (SGRQ), gender, race and CT measures of emphysema, gas trapping and airway wall thickness. 6MWD decline correlates relative to baseline and 5-year changes were examined using univariate and multivariate linear regression.Results At baseline, 2573 had normal spirometry; 487 were classified as GOLD1, 1044 as GOLD2, 514 as GOLD3 and 116 as GOLD4. Average 5-year decline in 6MWD was 35.6±101.7 (SD) metres (p<0.001). COPD participants experienced greater 6MWD decline (44.1±101.9 m, p<0.001) compared with those with normal spirometry (28.5±101.0 m, p<0.001). Only baseline 6MWD and study site accounted for appreciable fractions of 6MWD decline variance (R 2=12.1% and 9.1%, respectively). 5 year change in variables assessed (including FEV1 and SGRQ) explained only small fractions of 6MWD decline variance (each R2≤5%).Conclusion 6MWD declined significantly, but with high variability; spirometry, CT, health status, demographic and anthropometric measures accounted for only small portions of this variance. Our findings suggest that a meaningful decline in 6MWD observed over 5 years in COPD patients is in large part related to factors other than decline in pulmonary structure or function.",
  "authors": [
    {
      "affiliations": [
        "Department of Medicine, Section of Pulmonary, Critical Care, and Sleep Medicine, Baylor College of Medicine, Houston, Texas, USA"
      ],
      "name": "Aladin M Boriek"
    },
    {
      "affiliations": [
        "Respiratory Research Center, Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA",
        "Division of Respiratory and Critical Care Physiology and Medicine, Harbor-UCLA Medical Center, Torrance, California, USA"
      ],
      "name": "Joseph Gordon"
    },
    {
      "affiliations": [
        "Department of Biostatistics, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, USA"
      ],
      "name": "Yeongjin Gwon"
    },
    {
      "affiliations": [
        "Respiratory Research Center, Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA",
        "Department of Kinesiology, College of Health Sciences, University of Rhode Island, Kingston, Rhode Island, USA"
      ],
      "name": "Alessandra Adami"
    },
    {
      "affiliations": [
        "Respiratory Research Center, Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA",
        "Division of Respiratory and Critical Care Physiology and Medicine, Harbor-UCLA Medical Center, Torrance, California, USA"
      ],
      "name": "Janos Porszasz"
    },
    {
      "affiliations": [
        "Respiratory Research Center, Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA",
        "Division of Respiratory and Critical Care Physiology and Medicine, Harbor-UCLA Medical Center, Torrance, California, USA"
      ],
      "name": "Harry B Rossiter"
    },
    {
      "affiliations": [
        "Internal medicine, Interventional cardiology, WellMed Medical Management, San Antonio, San Antonio, Texas, USA"
      ],
      "name": "Mehdi Rambod"
    },
    {
      "affiliations": [
        "Department of Medicine, Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA"
      ],
      "name": "Divay Chandra"
    },
    {
      "affiliations": [
        "Division of Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital, Harvard Medical School, Brigham and Women’s Hospital, Boston, Massachusetts, USA"
      ],
      "name": "Alejandro A Diaz"
    },
    {
      "affiliations": [
        "Department of Epidemiology, Colorado School of Public Health, University of Colorado Denver, Aurora, Colorado, USA"
      ],
      "name": "Greg L Kinney"
    },
    {
      "affiliations": [
        "Department of Medicine, National Jewish Health, Denver, Colorado, USA"
      ],
      "name": "Barry J Make"
    },
    {
      "affiliations": [
        "Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham Health System, Birmingham, Alabama, USA"
      ],
      "name": "Merry-Lynn N McDonald"
    },
    {
      "affiliations": [
        "Department of Medicine, National Jewish Health, Denver, Colorado, USA"
      ],
      "name": "Elizabeth A Regan"
    },
    {
      "affiliations": [
        "Department of Medicine, University of Nebraska Medical Center, Omaha, Nebraska, USA"
      ],
      "name": "Stephen Rennard"
    },
    {
      "affiliations": [
        "Edinburgh Imaging, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, UK"
      ],
      "name": "Edwin J R van Beek"
    },
    {
      "affiliations": [
        "Respiratory Research Center, Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA",
        "Division of Respiratory and Critical Care Physiology and Medicine, Harbor-UCLA Medical Center, Torrance, California, USA"
      ],
      "name": "Richard Casaburi"
    }
  ],
  "title": "Correlates of 5-year decline in 6-min walk distance in the COPDGene cohort",
  "uid": "c3a9d58c-a9c8-57d3-bd73-36bb152419c9"
}