title: Early decline in six-minute walk distance from the time of diagnosis predicts clinical worsening in pulmonary arterial hypertension.
abstract: BACKGROUND
  The six-minute walk distance (6MWD) is commonly used to assess pulmonary arterial hypertension (PAH). However, the role of 6MWD in predicting outcomes in PAH is controversial. Clinical worsening is being increasingly considered as a clinically meaningful end point in PAH.
  
  
  OBJECTIVE
  We aimed to investigate whether early longitudinal changes in 6MWD (Δ6MWD) in meters and percent predicted (%pred) from the time of diagnosis predict clinical worsening of PAH.
  
  
  METHODS
  One hundred patients with group I PAH were retrospectively assessed. 6MWD was calculated using American (%pred US) or Canadian (%pred CAN) reference equations. Δ6MWD at 6 months were recorded. Clinical worsening was defined as either: development of right heart failure, hospital admission for PAH, referral for lung transplantation or initiation of prostanoids after oral therapy failed. Optimal 6-month differences in 6MWD to detect worsening were defined with receiver operating characteristics (ROC) analysis.
  
  
  RESULTS
  Progressors, i.e. patients with clinical worsening, and nonprogressors showed significant differences in Δ6MWD. The most clinically significant declines in 6MWD at 6 months were ≥35 m, ≥8%pred US and ≥6%pred CAN. ROC and Cox proportional hazard analyses showed equivalent results for 6MWD %pred and meters. Six-month declines in 6MWD predicted worsening with a high specificity (94%) but a low sensitivity (33%).
  
  
  CONCLUSIONS
  Early declines in 6MWD (within the first 6 months) predict future clinical worsening of PAH with high specificity. Δ6MWD may still be part of a comprehensive assessment of a patient's clinical status. However, given the poor sensitivity, a decline in 6MWD should be used with other clinical tools to make an appropriate assessment of the progression of PAH.
authors: Southwest Ontario Pulmonary Hypertension Clinic, Division of Respirology, Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, Ont., Canada.
authors: Julie
authors: J
authors: Huang
authors: Sanjay
authors: S
authors: Mehta
authors: Marco
authors: M
authors: Mura
mesh_terms: D018450:Disease Progression; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000209:etiology; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D006976:Hypertension, Pulmonary / Q000150:complications* / Q000401:mortality / Q000628:therapy; D016040:Lung Transplantation; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012017:Referral and Consultation / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016138:Walking