Oxygen desaturation during a 4-minute step test: predicting survival in idiopathic pulmonary fibrosis
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Data
2007-03-01
Autores
Stephan, Samia
Pereira, Carlos Alberto de Castro
Coletta, Ester Martins
Ferreira, Rimarcs Gomes
Otta, Jaquelina Sonoe
Nery, Luiz Eduardo
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Background and aim: PaO2 during exertion is a significant predictor of IPF survival. The aim of study was to assess oxygen desaturation for predicting survival in IPF patients at the end of a 4-minute step test. Methods: A longitudinal study was done in 59 patients with IPF from February 1998 to January 2005. Upon initial examination, lung function testing was performed, as were 4-minute step tests, in which patients stepped up and down on a 20-cm single step at a self-paced rate. In the final minute, oxygen saturation by pulse oximetry (SpO(2),) was measured. Results: Median survival was 58 months. SpO(2), at rest and during stepping, dyspnea score, as well as FVC% and DLCO% were found to be significant predictors of mortality. Desaturation to 89% or less correlated with a hazard ratio of 2.39 for IPF mortality (95% CI, 1.16-3.63; p < 0.0001). In patients with such desaturation, four-year survival was 39%, compared to 96% in those with no desaturation. In a multivariate Cox analysis, only SPO2 during stepping remained significant (p < 0.0001). A DLCO < 45% of predicted (n=40 patients) correlated with a hazard ratio of 2.23 for mortality (95% CI, 0.73-3.71; p < 0.0001). When the analysis was repeated including DLCO, SPO2 and DLCO remained significant (p < 0.05). Conclusion: Desaturation to 89% or less in a 4-minute step test is a strong predictor of mortality in IPF patients.
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Sarcoidosis Vasculitis And Diffuse Lung Diseases. Milano: Fondazione Pneumologia U I P Onlus, v. 24, n. 1, p. 70-76, 2007.