Six-minute-walk distance predicts waiting list survival in idiopathic pulmonary fibrosis

Am J Respir Crit Care Med. 2006 Sep 15;174(6):659-64. doi: 10.1164/rccm.200604-520OC. Epub 2006 Jun 15.

Abstract

Rationale: Functional studies may be useful to predict survival in idiopathic pulmonary fibrosis (IPF). Various cutoffs of 6-min-walk distance (6MWD) have been suggested to identify patients at a high risk of death.

Objectives: To examine the association between 6MWD and survival in patients with IPF listed for lung transplantation, and to identify sensitive and specific cutoffs for predicting death at 6 mo.

Methods: We performed a retrospective cohort study of 454 patients classified as having IPF listed for lung transplantation with the United Network for Organ Sharing between June 30, 2004 and July 22, 2005.

Measurements and main results: Lower 6MWD was associated with an increased mortality rate (p value for linear trend < 0.0001). Patients with a walk distance less than 207 m had a more than fourfold greater mortality rate than those with a walk distance of 207 m or more, despite adjustment for demographics, anthropomorphics, FVC % predicted, pulmonary hypertension, and medical comorbidities (adjusted rate ratio, 4.7; 95% confidence interval, 2.5-8.9; p < 0.0001). 6MWD was a significantly better predictor of 6-mo mortality than was FVC % predicted (c-statistic = 0.73 vs. 0.59, respectively; p = 0.02).

Conclusions: Lower 6MWD was strongly and independently associated with an increased mortality rate for wait-listed patients classified as having IPF. 6MWD was a better predictor of death at 6 mo than was FVC % predicted.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Exercise Test / methods
  • Female
  • Follow-Up Studies
  • Humans
  • Lung Transplantation*
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Prognosis
  • Pulmonary Fibrosis / mortality*
  • Pulmonary Fibrosis / physiopathology*
  • Pulmonary Fibrosis / surgery
  • Pulmonary Wedge Pressure
  • ROC Curve
  • Retrospective Studies
  • Survival Rate / trends
  • Time Factors
  • Waiting Lists*
  • Walking / physiology*