Final answer:
TrOOP, or True Out-Of-Pocket costs, is a term used by Medicare to track a member's actual expenses for medications. These costs influence when members transition between stages of their Medicare prescription drug plan.
Step-by-step explanation:
TrOOP stands for True Out-Of-Pocket costs. In the context of Medicare prescription drug coverage, this term refers to the actual expenses that a member incurs for their medications, which can include deductibles, coinsurance, and co-payments. Medicare tracks TrOOP costs to determine when a member moves between stages of their prescription drug plan, such as from the initial coverage stage to the coverage gap (also known as the 'donut hole') and then into catastrophic coverage. Specifically, it's the total amount that matters for progressing through these phases, which in turn affects the cost-sharing responsibilities of the member.