Background: The 6 min walk test (6MWT) provides prognostic information in various respiratory diseases, but limited data exist in cystic fibrosis (CF) adults.
Methods: Consecutive CF adults who performed 6MWT at Cochin Hospital (Paris, France) over 12 years were analyzed. The cut-off 6 min walking distance (6MWD) value that best predicted a combined endpoint (death without transplant or lung transplant) was established using a receiver operating curve. Determinants of low 6MWD or of desaturation (SpO2 ≤ 90%) during 6MWT were examined using multivariate logistic regressions. Prognostic value of these variables was assessed using Kaplan-Meier and Cox analyses.
Results: 6MWT was performed in 286 CF adults (median: age, 28 yr; FEV1, 45% predicted) of whom 14% (n = 40) had lung transplant and 6% (n = 18) died without transplant. 6MWD correlated with FEV1% predicted (r = 0.43; P < 0.001), but markedly differed in subjects within the same range of FEV1. A 6MWD ≤ 475 m predicted death or transplant and was mostly found in patients with FEV1 ≤ 60% predicted. Desaturation during the 6MWT occurred in 29% of patients, exclusively in subjects with FEV1 ≤ 60% predicted. Both 6MWD ≤ 475 m and desaturation during the 6MWT were independent predictors of death or transplant.
Conclusion: The 6MWT provides prognostic information in CF adults, especially in subjects with FEV1 ≤ 60% predicted.
Keywords: 6 min walk test; Adults; Cystic fibrosis; Prognosis.
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