18. Why should the weight loss of the last month be used, if the weight loss of the last 6 months is also available?
Throughout the use of the PG-SGA© or the Pt-Global app/web tool©, it is important to think of the patient in terms of whether the patient is anabolic or catabolic. Lean tissue/non-fluid weight increase tends to represent anabolism (positive nitrogen balance) whereas lean tissue/non-fluid weight decrease may represent catabolism in an ill patient.
Weight information is addressed along a continuum – 6 months (chronic), 1 month (intermediate), and past two weeks (acute) change. For example, if the patient’s weight is 100 lbs or 100 kg at 6 months and then decreased by 10% or increased by 10% (e.g., from 100 lbs/kg to 90 lbs/kg or 110 lbs/kg, respectively), the weight that is more recent lets you know what is going on more recently in terms of the patient metabolically in an intermediate setting.
If weight decreased, perhaps that is related to treatment or poor symptom control. If increased, perhaps it was excellent intervention by the professional to stop what had previously been uncontrolled disease or treatment related weight loss. The previous two weeks is a gauge of what is going on in the patient now metabolically or physiologically.
One uses the 1 month weight, if available, since it represents the intermediately chronic situation for which there are data regarding the prognostic implications.