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Six minute walk distance (6MWD) is routinely used as part of the assessment process for lung transplant recipients. However, there is a paucity of data supporting the impact of baseline 6MWD on transplant outcomes in advanced lung diseases.
In this study, clinical information was prospectively collected over a 28-month period from 376 patients with diverse lung diseases awaiting lung transplantation at two centres. Investigators compared data before transplantation, after transplantation and during the overall study period, with death as the primary end point.
In each analysis every 500 foot increase in the baseline 6MWD was found to be a significant predictor of survival. No other variables such as age, body mass index, forced expiratory volume in 1 s, waiting list times and native lung disease were significantly associated with survival. There was no significant interaction between the effects of 6MWD and the underlying lung disease.
The authors conclude that 6MWD is an important tool for assessing survival in lung transplant recipients for all native lung diseases. However, the study was underpowered to assess mortality in the individual lung diseases and is not generalisable to all patient populations with end stage disease. Furthermore, they do not report on any co-morbidities or physical disability which could affect 6MWD. More research is required in assessing 6MWD to determine if a single baseline measurement or subsequent measurements over time offer a better prognostic tool in lung transplant candidates. The authors also suggest that rehabilitative measures that improve 6MWD may, in turn, affect survival following lung transplantation. This requires further study.
▸ Martinu T, Babyak MA, O’Connell CF, et al, for the INSPIRE investigators. Baseline 6-min walk distance predicts survival in lung transplant candidates. Am J Transplant 2008;8:1–8