title: Impact of the transition to ICD-10 on Medicare inpatient hospital payments.
abstract: OBJECTIVE
  On October 1, 2013, the reporting of diagnoses and procedures in the U.S. will transition  from the clinical modification of the ninth revision of the International Classification of Diseases (ICD-9-CM) to the  tenth revision (ICD-10). We estimate the impact of conversion to ICD-10 on Medicare MS-DRG payments to hospitals using  2009 Medicare data.
  
  
  METHODS
  Using the ICD-9-CM MS-DRG v27 (FY 2010), the converted ICD-10 MS-DRG v27, and the ICD-10  to ICD-9-CM Reimbursement Map for fiscal year 2010, we estimate the impact on aggregate payments to hospitals and the  distribution of payments across hospitals.
  
  
  RESULTS
  Although the transition from the ICD-9-CM to the ICD-10 version of  MS-DRGs resulted in 1.68 percent of the patients being assigned to a different MS-DRG, payment increases and decreases  due to the changes in MS-DRG assignment essentially netted out, resulting in a minimal impact on aggregate payments to  hospitals (+0.05 percent) and on the distribution of payments across hospital types (-0.01 to +0.18 percent). Mapping  ICD-10 data back to ICD-9-CM, and using the ICD-9-CM MS-DRGs, resulted in 3.66 percent of patients being assigned to a  different MS-DRG, a modest decrease in aggregate payments to hospitals (-0.34 percent), and modest changes in the  distribution of payments across hospital types (-0.14 to -0.46 percent).
  
  
  CONCLUSIONS
  As demonstrated by MS-DRGs, a direct  conversion of an application to ICD-10 can produce consistent results with the ICD-9-CM version of the application.  However, the use of mappings between ICD-10 and ICD-9-CM will produce less consistent results, especially if the mapping  is not tailored to the specific application.
authors.affiliation: 3M Health Information Systems, Wallingford, Connecticut 06492, USA.
authors.forename: Ronald E
authors.initials: RE
authors.lastname: Mills
authors.forename: Rhonda R
authors.initials: RR
authors.lastname: Butler
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: McCullough
authors.forename: Mona Z
authors.initials: MZ
authors.lastname: Bao
authors.forename: Richard F
authors.initials: RF
authors.lastname: Averill
mesh_terms: D003953:Diagnosis-Related Groups / Q000191:economics / Q000458:organization & administration / Q000706:statistics & numerical data; D004469:Economics, Hospital / Q000458:organization & administration* / Q000706:statistics & numerical data; D006801:Humans; D007297:Inpatients / Q000706:statistics & numerical data; D038801:International Classification of Diseases / Q000458:organization & administration; D006278:Medicare / Q000191:economics / Q000458:organization & administration* / Q000706:statistics & numerical data; D012051:Reimbursement Mechanisms / Q000191:economics / Q000458:organization & administration / Q000706:statistics & numerical data; D014481:United States