Volumetric Outcome

Definition / Explanation

Formula

Other terms for this outcome in the included studies

Lymphedema Volume

The excess volume in the limb. The volume is measured in milliliters (mL). It is called ‘lymphedema volume’ because it is the amount of the limb volume that is attributed to lymphedema. Lymphedema volume is NOT the total volume of the limb. To calculate the lymphedema volume, you have to compare the affected limb to the unaffected limb by subtracting. In this review, we are interested in the lymphedema volume (or excess volume) that remains in the limb after treatment.

Post‐treatment total volume of the affected arm minus post‐treatment total volume of the unaffected arm.

Lymphedema volume

has also been called absolute lymphedema volume, post‐intervention volume (McNeely 2004), and excess limb volume (Williams 2002)

Volume Reduction

An estimate of how much the limb has been reduced (in ml) presumably from the treatment.

Lymphedema volume at baseline minus the lymphedema volume after treatment.

OR

Excess volume before treatment minus the excess volume after treatment.

Volume reduction

has also been called the mean lymphedema volume reduction (Johansson 1998; Johansson 1999) and mean change lymphedema volume (McNeely 2004)

Per cent Reduction

The decrease in excess volume relative to the amount of excess volume at baseline. Both the lymphedema volume and the volume reduction are considered absolute values not relative values. However, when absolute values are used, a person with a large excess limb volume might get a 2% reduction, but the amount can look large because the beginning volume was large. By contrast, a person with a small beginning volume, can get a 30% reduction, and it can look small in absolute terms. Thus, it is valuable to have a third way to think about lymphedema outcomes, and that is to look at the per cent change because that is a relative value.

Difference Test A – Difference Test B

____________________________________ x 100

Difference Test A

Where difference is the affected arm volume minus the unaffected arm volume (McNeely 2004)

Another way to think of per cent reduction is this formula:

Excess volume at baseline – Excess volume post‐treatment

______________________________________________x100

Excess volume at baseline

Per cent Reduction has also been called the percentage lymphedema reduction (Johansson 1998; Johansson 1999), per cent change, per cent reduction in lymphedema volume (McNeely 2004), percentage change in excess limb volume (Sitzia 2002)