Nunes Flavia S, Pastre Jean, Brown Anne W, Shlobin Oksana A, King Christopher, Weir Nargues A, Nathan Steven D
Inova Advanced Lung Disease and Transplant Program, Inova Fairfax Hospital, Falls Church, VA, USA.
Sarcoidosis Vasc Diffuse Lung Dis. 2021;38(1):e2021005. doi: 10.36141/svdld.v38i1.9258. Epub 2021 Mar 31.
The six-minute walk test (6MWT) is a readily available tool used to evaluate functional capacity in patients with idiopathic pulmonary fibrosis (IPF). However, it is often logistically challenging to perform in the context of a busy clinical practice. We sought to investigate if the 1MWT distance (1MWD) predicts the 6MWT distance (6MWD), and if an abbreviated walk could accurately predict outcomes in IPF patients.
Baseline demographics and pulmonary function testing of IPF patients evaluated at a tertiary referral center between 2010 and 2017 were collected. 6MWT variables at baseline as well as 1 and 6 minutes were collected. Time to death, lung transplantation, or most recent follow-up was ascertained.
There were 177 patients, the majority of whom (80%) were male. The mean age was 67 ± 9 years and mean FVC was 64 ± 18% predicted. Forty eight (27%) patients used oxygen supplementation during the 6MWT. The median 6MWD was 366 meters (IQR: 268-471) while the median 1MWD was 65 meters (IQR: 46-81). Stratified by the median, 89 patients were "High Walkers" based on the 6MWD ≥ 366m (HW) and 88 patients were "Low Walkers" (LW). HW had a higher FVC% (70 ± 15 vs 57 ± 18, p= 0.001), higher DLCO% (45 ± 12 vs 34 ± 14, p= 0.001) and higher 1MWD (83 ± 28 vs 47 ± 16, m p= 0.001). Median transplant-free survival was better in HW vs LW (27 ± 16 vs 22 ± 18 months, log rank p= 0.018). There was a strong correlation between the 1MWD and the 6MWD (r= 0.91, Spearman's correlation, p < 0.0001). Also, the transplant-free survival curves stratified by 1MWD were very similar to the curves for 6MWD, showing a lower survival in the LW cohort (log rank p= 0.009).
The 1MWD obtained during the first minute of a 6MWD shows a strong correlation to total 6MWD and retains its ability to predict transplant-free survival. 1MWT may serve as a practical substitute for the more cumbersome 6MWT. Our findings require further validation prospectively in larger cohorts of IPF patients.
六分钟步行试验（6MWT）是一种可用于评估特发性肺纤维化（IPF）患者功能能力的现成工具。然而，在繁忙的临床实践中进行该试验往往存在后勤方面的挑战。我们试图研究1分钟步行距离（1MWD）是否能预测6分钟步行距离（6MWD），以及缩短的步行试验能否准确预测IPF患者的预后。
收集2010年至2017年在一家三级转诊中心接受评估的IPF患者的基线人口统计学数据和肺功能测试结果。收集基线时以及步行1分钟和6分钟时的6MWT变量。确定患者的死亡时间、肺移植时间或最近一次随访时间。
共有177例患者，其中大多数（80%）为男性。平均年龄为67±9岁，平均用力肺活量（FVC）为预计值的64±18%。48例（27%）患者在6MWT期间使用了氧疗。6MWD的中位数为366米（四分位间距：268 - 471），而1MWD的中位数为65米（四分位间距：46 - 81）。按中位数分层，基于6MWD≥366米，89例患者为“高步行者”（HW），88例患者为“低步行者”（LW）。HW组的FVC%更高（70±15 vs 57±18，p = 0.001），一氧化碳弥散量（DLCO）%更高（45±12 vs 34±14，p = 0.001），1MWD更高（83±28 vs 47±16，米，p = 0.001）。HW组的无移植生存期中位数优于LW组（27±16 vs 22±18个月，对数秩检验p = 0.018）。1MWD与6MWD之间存在很强的相关性（r = 0.91，Spearman相关性，p < 0.0001）。此外，按1MWD分层的无移植生存曲线与6MWD的曲线非常相似，LW组的生存率较低（对数秩检验p = 0.009）。
在6MWD的第一分钟测得的1MWD与总的6MWD显示出很强的相关性，并保留了其预测无移植生存期的能力。1MWT可以作为更繁琐的6MWT的一种实用替代方法。我们的研究结果需要在更大规模的IPF患者队列中进行前瞻性进一步验证。
