A Review of the Six-Minute Walk Test: Its Implication as a Self-Administered Assessment Tool

I read with interest the review article by Du and colleagues published in the European Journal of Cardiovascular Nursing in July 2008. The concept that the six-minute walk test (6-MWT) could be adapted as a patient-reported outcome measure of functional capacity is interesting and the authors should be congratulated for pursuing this line of enquiry. However, after reading the manuscript I felt compelled to write this letter to highlight a number of inaccuracies and omissions that pervade the article. The authors claim in the preamble that the 6-MWT “has been devised as a practical sub-maximal walk test”. Whilst it is true that the 6-MWT is self-paced and may be submaximal in some patients (dependent upon age, sex, type and severity of co-morbidities, and degree of cardiac dysfunction, among others), a number of studies have indicated that it is a maximal test in some patients with chronic heart failure (CHF), left ventricular assist devices, and coronary artery disease [1–5]. This means that patients would be exercising above their anaerobic threshold during the completion of the 6-MWT. In Part 2 of their review the authors discuss data from two studies yet fail to report this crucial finding. Ingle and colleagues [6] reported that in elderly patients with left ventricular systolic dysfunction (LVSD) and in another cohort of patients with no major structural heart disease (MSHD), the 6-MWT should not be considered a maximal test of exercise capacity but rather a test of submaximal exercise performance. This study demonstrated that the 6-MWT takes place at a higher proportion of peak oxygen uptake in patients with LVSD compared to those with no MSHD, and may be one reason why fatigue is a more prominent symptom in these patients.