The MS-DRG methodology was implemented in 1983 as the first version of prospective payment methodology.  Because the amount of money that was to be impacted by the implementation of ICD-10 was a large and very real worry.  

One concern since the implementation of ICD-10 was the Medicare Severity Diagnosis Related Group (MS-DRGs) reimbursement methodology and the ICD-10 version of the methodology.  

This change was the largest change since 2007 when the Centers for Medicare and Medicaid (CMS) adopted MS-DRGs.    Hospitals were concerned if their case mix index (CMI) would significantly change or if the level of reimbursement would change. Anecdotally, hospitals have been reporting an increase in CMI.   


First, there have been changes in the Official Coding and Reporting Guidelines. If a patient has anemia due to a malignancy, the malignancy is now coded first.  Instead of a code for admission for physical therapy (ICD-9-CM V57.1 or V57.89), the condition is now reported as the principal diagnosis due to no code in ICD-10-CM for admission for or encounter for physical therapy.

Second, there are some issues with the ICD-10 version of the MS-DRG algorithm for v33. Some procedures that were not DRG operating room procedures in ICD-9-CM are now impacting the DRG assignment. One example: suture of the nose.    This procedure did not impact the DRG assignment in ICD-9-CM, but is impacting the DRG assignment in some situations under ICD-10. Issues were reported with v32 of the grouper and CMS has corrected the errors. One issue under v32 was the insertion of Cervidil to induce labor was impacting DRG assignment. The error was corrected for v33. It is a safe assumption CMS will continue to make updates that correct some problems with the methodology under ICD-10.

Third, there have been some MS-DRG methodology changes. An example of this change is the requirement of coding rehabilitation procedures (F section) to obtain the DRG 945 or 946 (Rehabilitation with or without CC). Another change is some diagnoses can act as a CC or MCC for itself when it is the principal diagnosis. Two examples of diagnoses that act as their own CC or MCC are third stage pressure ulcer of the elbow (MCC) or coronary artery disease with unstable angina (CC). This situation was never true under ICD-9-CM. 

Fourth, many organizations have focused on documentation education for their providers. It seems that this effort is paying off for many organization. Continued documentation education is encouraged as we continue under ICD-10.

How has your CMI has been impacted by the implementation of ICD-10? Have you noticed any errors in the methodology? The proposed rule for v34 should be released soon so the industry will be anxiously anticipating more changes to this reimbursement methodology.

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