Six-minute walk distance predicting the risk of mortality in lymphangioleiomyomatosis patients

Abstract Background The study aims to explore the value of the six-minute walk test (6MWT) in assessing the severity and prognosis of patients with lymphangioleiomyomatosis (LAM). Methods A retrospective analysis was conducted on 403 LAM patients from the LAM registry study at the Peking Union Medical College Hospital (PUMCH). Survival and progression datasets were constructed. Results: ROC curve analysis established the optimal cut-off value for the six-minute walk distance (6MWD) to predict increased risk of mortality was 425.5 m. The 6MWD low group (6MWD < 425.5 m) exhibited lower SpO₂, higher rates of desaturation, higher post-6MWT Borg dyspnea scale scores, worse pulmonary function indicators (FEV1%pred and DLCO%pred), and poorer quality of life assessments (SGRQ) (P < 0.001). Furthermore, the 6MWD showed a significant positive correlation with baseline FEV1%pred (P < 0.001). Multivariate regression analysis indicated that 6MWD, age, desaturation, and post-6MWT Borg dyspnea scale scores were independently correlated with baseline FEV1%pred (P < 0.001). Progression dataset analysis demonstrated no significant correlation between 6MWT parameters and the annual decline in FEV1. Kaplan-Meier survival curves showed a significantly reduced survival probability for patients with 6MWD < 425.5 m, desaturation, or post-6MWT Borg dyspnea scale≥2. Multivariate Cox regression indicated that 6MWD < 425.5 m (HR = 3.759, P = 0.0375), FEV1%pred < 70% (HR = 12.48, P = 0.0045), and sirolimus (HR = 0.1194, P < 0.001) were independent factors affecting survival in patients. Conclusions 6-minute walk distance effectively reflects the physical condition and prognosis and can be utilized as an important tool for clinical assessment in LAM patients.