Rationale and Hypothesis: Idiopathic pulmonary fibrosis is a fatal
disease with a variable rate of progression. We hypothesized that
changes in distance walked and quantity of desaturation during a
six-minute-walk test (6MWT) would add prognostic information to
changes in FVC or diffusing capacity for carbon monoxide.
Methods: One hundred ninety-seven patients with idiopathic pulmonary
fibrosis were evaluated. Desaturation during the 6MWT was
associated with increased mortality even if a threshold of 88%
was not reached. Baseline walk distance predicted subsequent walk
distance but was not a reliable predictor of subsequent mortality
in multivariate survival models. The predictive ability of serial
changes in physiology varied when patients were stratified by the
presence/absence of desaturation 88% during a baseline 6MWT.
For patients with a baseline saturation 88% during a 6MWT,
the strongest observed predictor of mortality was serial change in
diffusing capacity for carbon monoxide. For patients with saturation
88% during their baseline walk test, serial decreases in FVC
and increases in desaturation area significantly predicted subsequent
mortality, whereas decreases in walk distance and in diffusing
capacity for carbon monoxide displayed less consistent statistical
evidence of increasing mortality in our patients.
Conclusion: These data highlight the importance of stratifying patients
by degree of desaturation during a 6MWT before attributing
prognostic value to serial changes in other physiologic variables.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91940/1/2006 AJRCCM Idiopathic pulmonary fibrosis - Prognostic value of changes in physiology and six minute hallwalk.pd