Six-minute walk distance and survival time in patients with idiopathic pulmonary fibrosis in Brazil

• Published in: Jornal brasileiro de pneumologia Vol. 44; no. 4; pp. 267 - 272
• Main Authors: Mancuzo, Eliane Viana, Soares, Maria Raquel, Pereira, Carlos Alberto de Castro
• Format: Journal Article
• Language: English
• Published: Brazil Sociedade Brasileira de Pneumologia e Tisiologia 01.07.2018
• Subjects: Brazil; Doenças pulmonares intersticiais; Exercise Test - methods; Female; Fibrose pulmonar, Tolerância ao exercício; Humans; Idiopathic Pulmonary Fibrosis - mortality; Idiopathic Pulmonary Fibrosis - prevention & control; Male; Original; Physical Therapy Modalities; RESPIRATORY SYSTEM; Retrospective Studies; ROC Curve; Survival Rate; Walk Test; Brazil; Exercise tolerance; Pulmonary fibrosis; Fibrose pulmonar, Tolerância ao exercício; Doenças pulmonares intersticiais; Lung diseases, interstitial
• ISSN: 1806-3713; 1806-3756; 1806-3756
• DOI: 10.1590/s1806-37562018000000049

To determine the cut-off point for the six-minute walk distance (6MWD) that indicates lower survival time in patients with idiopathic pulmonary fibrosis (IPF) in Brazil. This was retrospective study carried out in two referral centers for IPF. The 6MWT was performed twice, considering the highest value of the 6MWD. Various cut-off points were estimated, in absolute values and in percentage of predicted values, using ROC curves, the Kaplan-Meier method, and data from other studies. The sample comprised 70 patients with IPF. The mean age was 71.9 ± 6.4 years, and 50 patients (71.4%) were male. The mean FVC was 76.6 ± 18.2% of predicted value. The mean SpO2 at rest before and after 6MWT were 93.8 ± 2.5% and 85.3 ± 6.5%, respectively. The median survival time was 44 months (95% CI: 37-51 months). The mean 6MWD was 381 ± 115 m (79.2 ± 24.0% of predicted). After the analyses, the best cut-off points for estimating survival were 6MWD < 330 m and < 70% of predicted. The median survival time of patients with a 6MWD < 330 m was 24 months (95% CI: 3-45 months), whereas that of those with a 6MWD ≥ 330 m was 59 months (95% CI: 41-77 months; p = 0.009). Similarly, the median survival times of those with a 6MWD < 70% and ≥ 70% of predicted, respectively, were 24 months (95% CI: 13-35 months) and 59 months (95% CI: 38-80 months; p = 0.013). Cox multivariate regression models including age, sex, smoking status, SpO2 at the end of the 6MWT, and FVC% showed that 6MWD remained significantly associated with survival (p = 0.003). Values of 6MWD < 330 m and < 70% of predicted value were associated with lower survival time in IPF patients in Brazil.