Could peak oxygen uptake be estimated from proposed equations based on the six-minute walk test in chronic heart failure subjects?

The study included only 36 stable adults aged 25 to 59 years with a body mass index under 30 kg/m2, so it may not apply to older, obese, or less stable patients. New York Heart Association class IV patients were excluded, even though the paper says they are the group that would benefit most from an evaluation such as the six-minute walk test. The sample was mostly men, with 29 men and 7 women, so the results may not reflect women with chronic heart failure. The patients had higher left ventricular ejection fraction, measured peak oxygen uptake, and walking distance than the samples used to create equations 1 to 3, which may make those equations less applicable to this group. The number of participants was small for comparing two measurements, and the study could not draw separate conclusions for each New York Heart Association class. One equation was developed in patients with cardiopulmonary disease rather than chronic heart failure specifically.

The authors declare no conflicts of interest.

Do not read equation 1's close average as proof it works for individual patients. The spread of individual errors was large, and the error increased as measured peak oxygen uptake rose.