TABLE 3.

Principle variables in 6-min walk test related to a poor prognosis in patients affected by COPD

	Value predictors of a poor prognosis
Distance m	≤334
6MWspeed m·s−1	≤0.8
6MWW m·kg−1	≤20 000
DSP %·m	≤290

6MWspeed: calculated by dividing the 6-min walk distance by the total walking time; 6MWW: 6-min walking work, the product of the 6-min walking distance and the patient weight; DSP: distance saturation product, the product of the 6-min walk distance and the lowest registered arterial oxygen saturation measured by pulse oximetry.