Six Minutes Walking to Predict Lung Disease Death

Idiopathic pulmonary fibrosis patients who walked farther in six minute test less likely to die

(RxWiki News) Idiopathic pulmonary fibrosis is a condition for which the cause is not known. Seeing how far a person can walk in six minutes may help doctors and patients understand the condition better.

A recent study found that distance walked during a six-minute walk test was a significant predictor of death by any cause in patients with idiopathic pulmonary fibrosis (scarring or thickening of the lungs without known cause).

The researchers found that age, hospitalizations and maximum amount of air breathed out of the lungs were also predictors of death by any cause.

"Ask your doctor about the risks and benefits of the six-minute walk test."

The lead author of this study was Roland M. du Bois, MD, from Imperial College in London, United Kingdom.

This study included 748 people with idiopathic pulmonary fibrosis (IPF) who took part in a previous study.

The average age of the participants in the current study was 66 years old. A total of 72 percent of the participants were male and 94 percent were white.

None of the participants were on the waiting list for a lung transplant, or had any heart, nerve or blood issues within the six months prior to the study.

Participants were eligible for the current study if they gave an interview at baseline and at 24 weeks in the original study.

The researchers assessed the participants' forced vital capacity (FVC) (the maximum amount of air that can be breathed out of the lungs) , dyspnea (shortness of breath), health-related quality of life and exercise capacity at baseline and after multiple 24-week periods.

Exercise capacity was measured using the 6-minute walk test (6MWT). The researchers measured how far a participant could walk during six minutes.

Risk factors associated with death were assessed during two 24-week periods.

These researchers found that there were a total of 79 deaths. Of these deaths, 67 were IPF-related.

The findings showed that the participants who lost more than 50 meters during the 6MWT between baseline and 24 weeks were 2.73 times more likely to die from any cause compared to the participants who lost 25 meters or fewer.

The participants who lost between 26 and 50 meters on their 6MWD between baseline and 24 weeks were 2.94 times more likely to die from any cause compared to participants who lost 25 meters or fewer.

The researchers also found that going fewer than 250 meters during the baseline 6MWT was associated with 2.12 times increased risk of death by any cause compared to being able to walk 350 meters or more during the baseline 6MWT.

Participants who walked between 250 and 349 meters during the baseline 6MWT were 28 percent more likely to have died due to any cause compared to the participants who walked 350 meters or more.

Having a previous respiratory hospitalization resulted in an increased risk of death by any cause by 3.54 times compared to not having a previous hospitalization.

The findings also revealed that participants who had 50 percent or less FVC at baseline were 6.86 times more likely to die from any cause compared to participants who had 80 percent or more FVC at baseline.

FVCs of 51 to 65 percent and 66 to 79 percent at baseline were associated with an increased risk of all-cause death by 2.92 times and 2.17 times, respectively.

The researchers determined that the participants who experienced a decrease in FVC of 10 percent or less at the end of 24 weeks were 5.86 times more likely to die by any cause, and participants who had a 5 to 9.9 percent decrease in FVC were 2.74 times more likely to die by any cause compared to participants who experienced a decrease in FVC of 5 percent or less after 24 weeks.

Lastly, participants 70 years old and older and those between 60 and 69 years old were 2.35 and 2.29 times more likely to die by any cause.

The authors mentioned a few limitations of their study. First, the sample size was small. Second, the researchers analyzed already recorded data. Third, the study excluded people who could not do the 6MWT without supplemental oxygen.

This study was published online ahead-of-print on December 5 in the European Respiratory Journal.

InterMune, Inc. provided funding for this research.

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Review Date: 
December 31, 2013