Does the shuttle walk test correlate with postoperative morbidity in lung surgery? Free

We read with interest Win and colleagues' article [1] on the evaluation of shuttle walk testing and correlation with postoperative morbidity in lung surgery. We are puzzled as to why the authors attempted to compare the mean shuttle walk distance (SWD) between the ‘good outcome group’ with the ‘poor outcome group’. Such a comparison is both statistically and clinically irrelevant and puts the cart before the horse instead of the other way round. It would be more appropriate to attempt to identify a cutoff shuttle walk distance which could separate the ‘good outcome group’ from the ‘poor outcome group’. If they had identified a distance of say, 250m, and analysed the postoperative outcome to see whether it predicted morbidity, it would have made a useful contribution. In their own study, the poor outcomes were considerably more in patients with a SWD less than 250m (8/12 patients, 66%) compared to those with a SWD more than 250m (26/91 patients, 29%). With a cutoff of 300m, the difference in postoperative poor outcome would be 51% (18/35 patients) vs. 24% (16/68 patients). Though only a detailed analysis of the individual patient data would identify statistical significance in these values, it does seem to be a clinically significant difference. Most studies [2–4] have shown exercise testing to be a useful tool in identifying patients with poor postoperative outcome and the results of this study do not mandate a change from this view.

References