Association of the position of a hospital-acquired condition diagnosis code with changes in medicare severity diagnosis-related group assignment.

Abstract

Incentives to improve quality include paying less for adverse events, including the Centers for Medicare and Medicaid Services' policy to not pay additionally for events classified as hospital-acquired conditions (HACs). This policy is controversial, as variable coding practices at hospitals may lead to differences in the inclusion and position of HACs in the list of codes used for Medicare Severity Diagnosis-Related Group (MS-DRG) assignment. Evaluate changes in MS-DRG assignment for patients with an HAC and test the association of the position of an HAC in the list of International Classification of Diseases, 9th Revision (ICD-9) diagnosis codes with change in MS-DRG assignment. Retrospective analysis of patients discharged from hospital members of the University HealthSystem Consortium's Clinical Data Base between October 2007 and April 2008. Comparisons were made between the MS-DRG assigned when the HAC was not included in the list of ICD-9 diagnosis codes and the MS-DRG that would have been assigned had the HAC code been included in the assignment. Of the 7027 patients with an HAC, 13.8% changed MS-DRG assignment when the HAC was removed. An HAC in the second position versus third position or lower was associated with a 40-fold increase in the likelihood of MS-DRG change. The position of an HAC in the list of diagnosis codes, rather than the presence of an HAC, is associated with a change in MS-DRG assignment. HACs have little effect on reimbursement unless the HAC is in the second position and patients have minor severity of illness.