The Utility of Preoperative Six-Minute-Walk Distance in Lung Transplantation

Abstract

Rationale: The use of 6-minute-walk distance (6MWD) as an indicator of exercise capacity to predict postoperative survival in lung transplantation has not previously been well studied.Objectives: To evaluate the association between 6MWD and postoperative survival following lung transplantation.Methods: Adult, first time, lung-only transplantations per the United Network for Organ Sharing database from May 2005 to December 2011 were analyzed. Kaplan-Meier methods and Cox proportional hazards modeling were used to determine the association between preoperative 6MWD and post-transplant survival after adjusting for potential confounders. A receiver operating characteristic curve was used to determine the 6MWD value that provided maximal separation in 1-year mortality. A subanalysis was performed to assess the association between 6MWD and post-transplant survival by disease category. Measurements and Main Results:A total of 9,526 patients were included for analysis. The median 6MWD was 787 ft (25th-75th percentiles = 450-1,082 ft). Increasing 6MWD was associated with significantly lower overall hazard of death (P , 0.001). Continuous increase in walk distance through 1,200-1,400 ft conferred an incremental survival advantage. Although 6MWD strongly correlated with survival, the impact of a single dichotomous value to predict outcomes was limited. All disease categories demonstrated significantly longer survival with increasing 6MWD (P < 0.009) except pulmonary vascular disease (P = 0.74); however, the low volume in this category (n = 312; 3.3%) may limit the ability to detect an association.Conclusions: 6MWD is significantly associated with posttransplant survival and is best incorporated into transplant evaluations on a continuous basis given limited ability of a single, dichotomous value to predict outcomes.Keywords: lung transplantation; exercise tolerance; patient outcome assessment The numbers of lung transplantations performed in the United States continue to increase, with more than 1,800 transplants performed in 2011 (1); however, 200-400 deaths continue to occur each year for those with end-stage pulmonary disease awaiting lung transplant (2). Given the scarcity of lung allografts (3), identifying measures to risk-stratify potential transplant recipients based on expected outcome following lung transplantation is of critical importance.Six-minute-walk distance (6MWD) is a commonly used and reproducible measure to evaluate exercise capacity in patients with severe cardiac or pulmonary disease (4). This metric has been shown to accurately predict survival in several pulmonary diseases including chronic obstructive pulmonary disease (5, 6), idiopathic pulmonary fibrosis (7), and primary In accordance with the United Network of Organ Sharing and U.S. Lung Allocation score metrics, distances are quantified in feet. The conversion from feet to meters is 3.28 ft = 1 m.

Safety and efficacy of bridging to lung transplantation with antifibrotic drugs in idiopathic pulmonary fibrosis: a case series

“…As they may attenuate disease progression, these antifibrotics may thus allow for valuable added time on the LTx waiting list. Next to FVC, 6MWT has also been shown to be a valid outcome measure, both in IPF, in whom the clinically important difference in 6MWT distance is reported to be 24–45 m [3–5] and in whom 6MWT is associated with changes in pulmonary function and quality-of-life [16]; and in patients awaiting LTx, in whom it is associated with post-transplant survival [17]. A reduction of the decline in 6MWT was also observed in treated patients compared to placebo in pooled analyses of IPF trials [3–5], which may partly explain why 6MWT overall remained relatively stable during treatment in our cohort, next to the obvious beneficial effects of cardio-pulmonary rehabilitation is some patients.…”

Frailty in Pulmonary and Critical Care Medicine

“…In addition, lower preoperative 6-minute-walk distance and serum albumin (potentially reflecting malnutrition) is associated with mortality after lung transplantation across disease types (59,60).…”

Older candidates for kidney transplantation: Who to refer and what to expect?

“…We are not aware of any studies to date that have measured physical performance and correlated these with outcomes in kidney transplant patients. In other solid organ transplant candidates, particularly in lung transplant, the six-minute walk test (6MWT)[21] has been used routinely in pre-transplant evaluations and has been shown to be a predictor of morbidity and mortality[22,23]. The 6MWT measures the distance that a patient can quickly walk on a flat, hard surface in a period of 6 min.…”