Lettieri Christopher J, Nathan Steven D, Browning Robert F, Barnett Scott D, Ahmad Shahzad, Shorr Andrew F
Pulmonary & Critical Care Medicine, Walter Reed Army Medical Center, 6900 Georgia Ave., NW, Washington, DC 20307, USA.
Respir Med. 2006 Oct;100(10):1734-41. doi: 10.1016/j.rmed.2006.02.004. Epub 2006 Mar 20.
The 6-min walk test (6MWT) has prognostic value in various pulmonary disorders including idiopathic pulmonary fibrosis (IPF). We determined the individual prognostic accuracy of distance walked and oxygen saturation during the 6MWT in patients with IPF. We defined a new composite index, the distance-saturation product (DSP), which is the product of distance walked and lowest oxygen saturation during the 6-min walk test. We compared the performance of the DSP to the individual 6MWT parameters in predicting mortality.
We evaluated pulmonary function tests, 6-min walk parameters and the DSP between survivors and non-survivors. The ability of each measure to discriminate outcomes was determined by receiver operator curves.
81 patients (48 survivors, 33 non-survivors) were included. Pulmonary function tests were similar and did not correlate with survival. Desaturation was greater (89.4% versus 83.7%, P<0.001) and distance walked was lower (406.9 versus 181.3m, P = 0.005) in non-survivors. The DSP was significantly lower among non-survivors (364.8 versus 153.5m%, P < 0.001) and predicted mortality more accurately than either individual 6MWT component (P = 0.035 versus desaturation, P=0.040 versus distance). A DSP <200 m% was associated with a seven-fold greater risk of 12-month mortality and an 18.0% shorter median survival compared with a DSP > 200 m% (P < 0.001).
Each component of the 6-min walk independently predicted mortality in IPF with greater accuracy than spirometry. However, a composite of both parameters, the DSP, provides slightly greater accuracy and represents a novel measure for assessing survival in patients with IPF.
6分钟步行试验（6MWT）在包括特发性肺纤维化（IPF）在内的各种肺部疾病中具有预后价值。我们确定了IPF患者在6MWT期间行走距离和血氧饱和度的个体预后准确性。我们定义了一个新的综合指数，即距离-饱和度乘积（DSP），它是6分钟步行试验期间行走距离与最低血氧饱和度的乘积。我们比较了DSP与6MWT各个参数在预测死亡率方面的表现。
我们评估了存活者和非存活者的肺功能测试、6分钟步行参数和DSP。通过受试者工作特征曲线确定每种测量方法区分结果的能力。
纳入81例患者（48例存活者，33例非存活者）。肺功能测试相似，且与生存率无关。非存活者的血氧饱和度下降更明显（89.4%对83.7%，P<0.001），行走距离更低（406.9对181.3米，P = 0.005）。非存活者的DSP显著更低（364.8对153.5米%，P < 0.001），并且比6MWT的任何一个单独组成部分更准确地预测死亡率（与血氧饱和度下降相比P = 0.035，与行走距离相比P=0.040）。与DSP>200米%相比，DSP<200米%与12个月死亡率高7倍以及中位生存期短18.0%相关（P < 0.001）。
6分钟步行试验的每个组成部分在预测IPF患者死亡率方面比肺活量测定法具有更高的准确性。然而，这两个参数的综合指标DSP提供了略高的准确性，并且代表了一种评估IPF患者生存率的新方法。
