Change in MS-DRG assignment and hospital reimbursement as a result of Centers for Medicare & Medicaid changes in payment for hospital-acquired conditions: is it coding or quality?

Context: In October 2008, the Centers for Medicare & Medicaid Services reduced payments to hospitals for a group of hospital-acquired conditions (HACs) not documented as present on admission (POA). It is unknown what proportion of Medicare severity diagnosis related group (MS-DRG) assignments will change when the International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM) diagnosis code for the HAC is not taken into account even before considering the POA status.

Objectives: The primary objectives were to estimate the proportion of cases that change MS-DRG assignment when HACs are removed from the calculation, the subsequent changes in reimbursement to hospitals, and the attenuation in changes in MS-DRG assignment after factoring in those that may be POA.