The Part D Prescriber National Summary Report, Calendar Year 2018 provides information on prescription drugs prescribed by individual physicians and other health care providers and paid for under the Medicare Part D Prescription Drug Program. The Part D Prescriber National Summary Report is based on information from CMS’s Chronic Conditions Data Warehouse, which contains Prescription Drug Event records submitted by Medicare Advantage Prescription Drug (MAPD) plans and by stand-alone Prescription Drug Plans (PDP). For each drug, the dataset includes the total number of prescriptions that were dispensed, which include original prescriptions and any refills, and the total drug cost. The total drug cost includes the ingredient cost of the medication, dispensing fees, sales tax, and any applicable administration fees and is based on the amount paid by the Part D plan, Medicare beneficiary, government subsidies, and any other third-party payers.