Six-minute walk distance (6MWD) dichotomized over/under 150 feet is one of 15 variables included in the Lung Allocation Score (LAS), however the independent association of 6MWD with waitlist mortality among lung transplant candidates is not well defined. Our objective was therefore to analyze this relationship using a large, national registry.
METHODS: Adult, lung-only candidates per the OPTN/UNOS database from 05/2005-12/2011 were analyzed. Generalized linear models and Cox proportional hazard models were used to determine the association between 6MWD and waitlist mortality after adjusting for potential confounders. Recursive partitioning and receiver operating characteristics (ROC) curve were used to assess optimal cutoff points with respect to 6-month waitlist deaths.
RESULTS: 12,298 patients were included. Overall 6-month waitlist mortality was 8.8%. Increasing 6MWD quartile was associated with significantly improved waitlist survival.
As a continuous variable, increasing 6MWD was associated with significantly lower waitlist mortality at 30-days [adjusted odds ratio (AOR) per 200 feet 0.48, 95% confidence interval (C I) 0.43-0.53], 3-months (AOR 0.60, CI 0.57-0.64), and 6-months (AOR 0.67, CI 0.64-0.70) as well as reduced overall risk of death (adjusted hazard ratio 0.77, CI 0.75-0.79) (p<0.0001 for all). Recursive partitioning of 6MWD by over/under 108 feet provided maximal separation in 6-month censored survival (172 vs 101 days, respectively); however, the 6MWD with optimal sensitivity and specificity for predicting death at 6-months was 550 feet.
CONCLUSIONS: 6MWD as a continuous variable is significantly associated with waitlist mortality. Future iterations of the LAS should consider the full range of 6MWD values in order to minimize waitlist deaths.
To cite this abstract in AMA style:Castleberry A, Englum B, Snyder L, Worni M, Osho A, Pietrobon R, Palmer S, Davis R, Hartwig M. Utility of Six-Minute Walk Distance in Predicting Waitlist Mortality for Lung Transplant Candidates, The [abstract]. Am J Transplant. 2013; 13 (suppl 5). https://atcmeetingabstracts.com/abstract/utility-of-six-minute-walk-distance-in-predicting-waitlist-mortality-for-lung-transplant-candidates-the/. Accessed May 7, 2021.
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