Duncan Michael J, Mota Jorge, Carvalho Joana, Nevill Alan M
Centre for Applied Biological and Exercise Science, Coventry University, Coventry, United Kingdom.
University of Porto, Faculty of Sports/Research Centre in Physical Activity, Health and Leisure-CIAFEL, Porto, Portugal.
PLoS One. 2015 Sep 29;10(9):e0139629. doi: 10.1371/journal.pone.0139629. eCollection 2015.
This study compared actual 6 minute walk test (6MWT) performance with predicted 6MWT using previously validated equations and then determined whether allometric modelling offers a sounder alternative to estimating 6MWT in adults aged 50-80 years.
We compared actual 6MWT performance against predicted 6MWT in 125 adults aged 50-85 years (62 male, 63 female). In a second sample of 246 adults aged 50-85 years (74 male, 172 female), a new prediction equation for 6MWT performance was developed using allometric modelling. This equation was then cross validated using the same sample that the other prediction equations were compared with.
Significant relationships were evident between 6MWT actual and 6MWT predicted using all of the commonly available prediction equations (all P<0.05 or better) with the exception of the Alameri et al prediction equation (P>0.05). A series of paired t-tests indicated significant differences between 6MWT actual and 6MWT predicted for all available prediction equations (all P<0.05 or better) with the exception of the Iwama et al equation (P = .540). The Iwama et al equation also had similar bias (79.8m) and a coefficient of variation of over 15%. Using sample 2, a log-linear model significantly predicted 6MWT from the log of body mass and height and age (P = 0.001, adjusted R2 = .526), predicting 52.6% of the variance in actual 6MWT. When this allometric equation was applied to the original sample, the relationship between 6MWT actual and 6MWT predicted was in excess of values reported for the other previously validated prediction equations (r = .706, P = 0.001). There was a significant difference between actual 6MWT and 6MWT predicted using this new equation (P = 0.001) but the bias, standard deviation of differences and coefficient of variation were all less than for the other equations.
Where actual assessment of the 6MWT is not possible, the allometrically derived equation presented in the current study, offers a viable alternative which has been cross validated and has the least SD of differences and smallest coefficient of variation compared to any of the previously validated equations for the 6MWT.
本研究将6分钟步行试验（6MWT）的实际表现与使用先前验证过的方程预测的6MWT进行比较，然后确定异速生长模型是否为估算50至80岁成年人的6MWT提供了更可靠的替代方法。
我们将125名年龄在50至85岁之间的成年人（62名男性，63名女性）的6MWT实际表现与预测的6MWT进行了比较。在第二个由246名年龄在50至85岁之间的成年人（74名男性，172名女性）组成的样本中，使用异速生长模型开发了一个新的6MWT表现预测方程。然后使用与其他预测方程进行比较的相同样本对该方程进行交叉验证。
使用所有常用的预测方程，6MWT实际值与预测值之间存在显著关系（所有P<0.05或更佳），但阿拉梅里等人的预测方程除外（P>0.05）。一系列配对t检验表明，除岩间等人的方程外（P = 0.540），所有可用预测方程的6MWT实际值与预测值之间均存在显著差异（所有P<0.05或更佳）。岩间等人的方程也有类似的偏差（79.8米），变异系数超过15%。使用样本2，对数线性模型通过体重、身高和年龄的对数显著预测了6MWT（P = 0.001，调整后R2 = 0.526），预测了实际6MWT中52.6%的方差。当将这个异速生长方程应用于原始样本时，6MWT实际值与预测值之间的关系超过了其他先前验证过的预测方程所报告的值（r = 0.706，P = 0.001）。使用这个新方程预测的6MWT实际值与预测值之间存在显著差异（P = 0.001），但其偏差、差异标准差和变异系数均小于其他方程。
在无法进行6MWT实际评估的情况下，本研究中通过异速生长得出的方程提供了一种可行的替代方法，该方程已经过交叉验证，与任何先前验证过的6MWT方程相比差异标准差最小，变异系数最小。
