Background:

The 6 minute walk is an inexpensive, low-technology test for measuring a patient's functional capacity and overall fitness. The utility of 6 minute walk test (6MWT) in kidney transplant evaluation and its associations with post-transplant clinical outcomes have not been described.

Methods:

We performed a retrospective study of kidney transplant recipients at one large center (2000 to 2014) who underwent 6MWT before transplantation. A questionnaire administered during the evaluation asked candidates “How far can you walk without difficulty?” Patients with answers indicating limited ability were further evaluated by the 6MWT. Associations between walking distance and post-transplant graft failure and patient death were examined by Cox regression including adjustment for recipient, donor and transplant factors.

Results:

During the study period, 489 recipients underwent 6MWT and were categorized according to quartile of walking distance as: short walk (n=123) (<1101 feet), medium walk (n=246, middle quartiles) (1101-1414 feet), and long walk (n=121) (>1414 feet).

Compared to long walk distance, short 6MWT distance was not associated with increased risk for graft failure or patient death at 1, 3, and 5 years post-transplant after covariate adjustment. However, at 10 years, short 6MWT distance was independently associated with increased risk of graft failure (aHR 4.2, CI 1.84–9.57). To a lesser degree, medium 6MWT distance was also associated with higher risk of graft failure (aHR 2.22, CI 1.03–4.8) compared to the short walk distance. No significant differences were noted in risks of post-transplant mortality according to 6MWT level.

Conclusion:

Results of a 6MWT correlated with long-term but not short-term graft outcomes after kidney transplantation. This observation may reflect selection bias for other favorable characteristics predicting excellent 5 year outcomes among candidates with short walk capacity chosen for transplantation. Further work should examine the implications of 6MWT for access to transplantation and waitlist survival.

CITATION INFORMATION: Alhamad T, Lentine K, Anwar S, Maw T, Horwedel T, Peng J, Saffaf K, Hagopian J, Delos Santos R, Malone A, Brennan D. Functional Capacity Pre-Transplantation Measured by 6 Minute Walk Test and Clinical Outcomes. Am J Transplant. 2016;16 (suppl 3).

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