Division of Allergy, Pulmonary, and Critical Care Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, USA.
Respir Med. 2020 Apr-May;165:105933. doi: 10.1016/j.rmed.2020.105933. Epub 2020 Mar 19.
The 6-min walk test (6MWT) is a commonly used clinical assessment of exercise capacity in patients with cardiopulmonary or neuromuscular disease, but normal values are lacking for young adults, who are frequent subjects of testing.
In a two-center study, 272 young adults, ages 18-50, underwent American Thoracic Society protocolized 6-min walk testing, and 56 underwent repeat testing. A linear regression model was developed based on anthropomorphic data. This model was compared to existing prediction equations.
Median 6MWD for the cohort was 637 m (IQR 584-686 m) and was not significantly impacted by age. This is in contrast to existing equations extrapolated from older subjects that predict increasing 6MWD in younger subjects. We found weak correlation of 6MWD with height, weight, BMI, and resting heart rate. Heart rate at completion correlated most strongly with 6MWD (rho 0.53 p < 0.0001). Repeat 6MWD was surprisingly variable, with a median difference between tests of 32.5 ± 31.9 m. Established reference equations performed poorly in this population, largely because age has much less effect on 6MWD in this group than in older adults.
Established reference equations should be reconfigured to include data from young adults, as age has minimal effect on 6MWD in this population. Heart rate response may be a valuable measure of effort in normal subjects. Six-minute walk distance, as with pulmonary function and exercise testing, should have predictive equations across the spectrum of age to allow for accurate assessment of exercise limitation.
6 分钟步行测试（6MWT）是一种常用于心肺或神经肌肉疾病患者运动能力评估的临床测试方法，但缺乏年轻人的正常值，而年轻人是测试的常见对象。
在一项两中心研究中，272 名年龄在 18-50 岁的年轻人接受了美国胸科学会制定的 6 分钟步行测试，其中 56 人接受了重复测试。根据人体测量数据建立了一个线性回归模型。将该模型与现有的预测方程进行了比较。
该队列的中位 6MWD 为 637m（IQR 584-686m），与年龄无关。这与从老年人推断的现有预测方程形成对比，这些方程预测年轻人的 6MWD 会增加。我们发现 6MWD 与身高、体重、BMI 和静息心率的相关性较弱。完成时的心率与 6MWD 相关性最强（rho 0.53 p<0.0001）。重复 6MWD 差异很大，两次测试之间的中位差异为 32.5±31.9m。现有的参考方程在该人群中的表现不佳，主要是因为年龄对该组 6MWD 的影响远小于老年人。
应该重新配置现有的参考方程，纳入年轻人的数据，因为年龄对该人群 6MWD 的影响很小。心率反应可能是正常受试者努力程度的一个有价值的衡量标准。与肺功能和运动测试一样，6 分钟步行距离应该在整个年龄范围内有预测方程，以准确评估运动受限。
