This variable is the dollar amount that the beneficiary paid for the PDE without being reimbursed by a third party.
The amount includes all copayments, coinsurance, deductible, or other patient payment amounts, and comes directly from the source PDE. This amount contributes to a beneficiary's true out-of-pocket (TrOOP) costs, but only if it is for a Part D-covered drug (i.e., spending on non-covered drugs does not count toward the TrOOP amount).
Three other variables measure payments that are made on behalf of the beneficiary and reduce the amount that he/she would normally have to pay for LICS_AMT (amount paid by Part D low-income subsidy), OTHER_TROOP_AMT (other third-party payments that count towards the TrOOP amount), and PLRO_AMT (other third-party payments that do not count towards the TrOOP amount).
If you want to know the beneficiary's total liability for the drug (i.e., the amount that the Part D plan did not cover), you must sum this variable and the 3 variables listed above.