Smith Benjamin M, Hoffman Eric A, Rabinowitz Dan, Bleecker Eugene, Christenson Stephanie, Couper David, Donohue Kathleen M, Han Meilan K, Hansel Nadia N, Kanner Richard E, Kleerup Eric, Rennard Stephen, Barr R Graham
Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, USA Department of Medicine, McGill University, Montreal, Canada.
Departments of Radiology, Medicine and Biomedical Engineering, University of Iowa, Iowa City, Iowa, USA.
Thorax. 2014 Nov;69(11):987-96. doi: 10.1136/thoraxjnl-2014-205160. Epub 2014 Jun 13.
COPD is characterised by reduced airway lumen dimensions and fewer peripheral airways. Most studies of airway properties sample airways based upon lumen dimension or at random, which may bias comparisons given reduced airway lumen dimensions and number in COPD. We sought to compare central airway wall dimensions on CT in COPD and controls using spatially matched airways, thereby avoiding selection bias of airways in the lung.
The Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study and Subpopulations and Intermediate Outcomes in COPD Study (SPIROMICS) recruited smokers with COPD and controls aged 50-79 years and 40-80 years, respectively. COPD was defined by current guidelines. Using CT image data, airway dimensions were measured for all central airway segments (generations 0-6) following 5 standardised paths into the lungs. Case-control airway comparisons were spatially matched by generation and adjusted for demographics, body size, smoking, CT dose, per cent emphysema, airway length and lung volume.
Among 311 MESA COPD participants, airway wall areas at generations 3-6 were smaller in COPD compared with controls (all p<0.001). Among 1248 SPIROMICS participants, airway wall areas at generations 1-6 were smaller (all p<0.001), and this reduction was monotonic with increasing COPD severity (p<0.001). In both studies, sampling airways by lumen diameter or randomly resulted in a comparison of more proximal airways in COPD to more peripheral airways in controls (p<0.001) resulting in the appearance of thicker walls in COPD (p<0.02).
Airway walls are thinner in COPD when comparing spatially matched central airways. Other approaches to airway sampling result in comparisons of more proximal to more distal airways and potentially biased assessment of airway properties in COPD.
慢性阻塞性肺疾病（COPD）的特征是气道管腔尺寸减小和外周气道数量减少。大多数关于气道特性的研究基于管腔尺寸或随机对气道进行采样，鉴于COPD患者气道管腔尺寸减小和数量减少，这可能会使比较产生偏差。我们试图使用空间匹配的气道比较COPD患者和对照组在CT上的中央气道壁尺寸，从而避免肺部气道选择偏差。
动脉粥样硬化多民族研究（MESA）COPD研究以及COPD研究中的亚组和中间结局研究（SPIROMICS）分别招募了年龄在50 - 79岁的COPD吸烟者和年龄在40 - 80岁的对照组。COPD由现行指南定义。利用CT图像数据，沿着5条标准化路径进入肺部，测量所有中央气道节段（0 - 6级）的气道尺寸。病例对照气道比较按级别进行空间匹配，并针对人口统计学、体型、吸烟、CT剂量、肺气肿百分比、气道长度和肺容积进行调整。
在311名MESA COPD参与者中，与对照组相比，3 - 6级气道壁面积在COPD患者中较小（所有p<0.001）。在1248名SPIROMICS参与者中，1 - 6级气道壁面积较小（所有p<0.001），并且这种减小与COPD严重程度增加呈单调关系（p<0.001）。在两项研究中，按管腔直径或随机采样气道会导致COPD中更多近端气道与对照组中更多外周气道进行比较（p<0.001），从而导致COPD中气道壁看起来更厚（p<0.02）。
在比较空间匹配的中央气道时，COPD患者的气道壁更薄。其他气道采样方法会导致更多近端气道与更多远端气道进行比较，并可能使COPD气道特性评估产生偏差。
