title: Prognostic value of desaturation during a 6-minute walk test in idiopathic interstitial pneumonia.
abstract: Exercise-induced hypoxia is an index of the severity of interstitial lung disease. We hypothesized that desaturation during a 6-minute walk test would predict mortality for patients with usual interstitial pneumonia (n = 83) and nonspecific interstitial pneumonia (n = 22). Consecutive patients with biopsy-proven disease performed a 6-minute walk test between January 1996 and December 2001. Desaturation was defined as a fall in oxygen saturation to 88% or less during the 6-minute walk test. Desaturation was common (44 of 83 usual interstitial pneumonia and 8 of 22 nonspecific interstitial pneumonia; chi square, p = 0.39). Patients with usual interstitial pneumonia or nonspecific interstitial pneumonia who desaturated had a significantly higher mortality than patients who did not desaturate (respective log-rank tests, p = 0.0018, p = 0.0089). In patients with usual interstitial pneumonia, the presence of desaturation was associated with an increased hazard of death (hazard ratio, 4.2; 95% confidence interval, 1.40, 12.56; p = 0.01) after adjusting for age, sex, smoking, baseline diffusion capacity for carbon monoxide, FVC, and resting saturation. We conclude that knowledge of desaturation during a 6-minute walk test adds prognostic information for patients with usual interstitial pneumonia and nonspecific interstitial pneumonia.
authors.affiliation: Department of Radiology, University of Michigan Health System, University of Michigan School of Public Health, Ann Arbor, MI 48109-0360, USA.
authors.forename: Vibha N
authors.initials: VN
authors.lastname: Lama
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Flaherty
authors.forename: Galen B
authors.initials: GB
authors.lastname: Toews
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Colby
authors.forename: William D
authors.initials: WD
authors.lastname: Travis
authors.forename: Qi
authors.initials: Q
authors.lastname: Long
authors.forename: Susan
authors.initials: S
authors.lastname: Murray
authors.forename: Ella A
authors.initials: EA
authors.lastname: Kazerooni
authors.forename: Barry H
authors.initials: BH
authors.lastname: Gross
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Lynch
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Martinez
mesh_terms: D015331:Cohort Studies; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000097:blood / Q000401:mortality / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010108:Oxyhemoglobins / Q000378:metabolism; D011379:Prognosis; D016138:Walking / Q000502:physiology*
chemical_list: D010108:Oxyhemoglobins