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Highlights from Proposed Changes to MS-DRG Classifications in the FY 2022 IPPS Proposed Rule

Published on 

Wednesday, May 19, 2021

 | Billing 
 | Coding 
 | Quality 

CMS issued the FY 2022 IPPS Proposed Rule (CMS-1762-IFC) on Tuesday April 27, 2021. You can find a high level review of what is being proposed in a related MMP article (link). This article focuses on two topics in section D, Proposed Changes to Specific MS-DRG Classifications, of the Proposed Rule. Each topic synopsis also includes the potential financial impact if the proposal is finalized.

In the proposed rule, CMS acknowledges the impact that the COVID-19 Public Health Emergency (PHE) had during FY 2020. Subsequently, they have proposed to use FY 2019 data to approximate the expected FY 2022 inpatient hospital utilization.

Calculating the potential financial impact of proposals was accomplished through a collaboration with RealTime Medicare Data (RTMD). RTMD’s database currently includes Medicare Fee-for-Service paid claims data for all U.S. states and territories except Kentucky and Ohio. The potential financial impacts noted in this article represent FY 2019 Medicare Fee-for-Service claims data for all 48 states in RTMD’s footprint collectively.

Type II Myocardial Infarction

“Type 2 myocardial infarction (myocardial infarction due to demand ischemia or secondary to ischemic imbalance) is assigned to code I21.A1, Myocardial infarction type 2 with the underlying cause coded first.”

Source: ICD-10-CM Official Guidelines for Coding and Reporting FY 2021 (link)

A requestor noted that when a type 2 Myocardial infarction (MI) is coded and the principal diagnosis is in MDC 5 (Diseases and Disorders of the Circulatory System), the Grouper logic assigns the MI to the following MS-DRGs:

  • MS-DRGs 280, 281 & 282: Acute Myocardial Infarction, Discharged Alive with MCC, with CC, and without CC/MCC, respectively, and
  • MS-DRGs 283, 284 & 285: Acute Myocardial Infection, Expired with MCC, with CC, and without CC/MCC, respectively.

The requestor asked if this Grouper logic is appropriate. Through analysis and consultation with their clinical advisors, CMS determined that the current Grouper logic is correct and no proposal for change was made.

During their analysis, CMS did note an issue with a Type 2 MI and the Grouper logic for MS-DRGs 222 and 223 (Cardiac Defibrillator Implant with Cardiac Catheterization with AMI, HF, or Shock with and without MCC, respectively). Currently, Type 2 MI is one of the listed principal diagnosis codes in the logic for this DRG pair. However, Type 2 MI as a secondary diagnosis is not recognized.

Simply put, this means that currently an encounter for a patient undergoing a cardiac defibrillator implant with cardiac catheterization and a Type 2 MI sequences to MS-DRGs 224 and 225 (Cardiac Defibrillator Implant with Cardiac Catheterization without AMI, HF, or Shock with and without MCC).

Clinical advisors recommended, and CMS is proposing to add special logic in MS-DRGs 222 and 223 “to allow cases reporting diagnosis I21.A1…as a secondary diagnosis to group to MS-DRGs 222 and 223 when reported with a listed procedure code for clinical consistency with the other MS-DRGs describing acute myocardial infarction.”

Potential Impact of Type II MI Proposal

Across the RTMD footprint, in FY 2019:

  • 208 claims with a secondary diagnosis of type 2 MI grouped to MS-DRG 224 (Cardiac Defibrillator Implant with Cardiac Catheterization without AMI, HF, or Shock with MCC),
  • CMS paid $10,938,624.59 to hospitals for MS-DRG 224 claims.
  • In FY 2019, the national average payment for the Cardiac Defibrillator MS-DRG with AMI (MS-DRG 222), was $3,967.69 more than MS-DRG 224.
  • The national average difference in payment multiplied by the volume of MS-DRG 224 claims equates to an underpayment amount to hospitals of $825,279.52.

Viral Cardiomyopathy

There are five ICD-10-CM diagnosis codes in the Viral Carditis subcategory B33.2. Currently, four of the codes are assigned to the Circulatory MDC 05:

  • B33.20: Viral carditis, unspecified,

  • B33.21: Viral endocarditis,
  • B33.22: Viral myocarditis, and
  • B33.23: Viral pericarditis.

However, the remaining code, B33.24 (Viral cardiomyopathy) is assigned to MDC 18 (Infectious and Parasitic Diseases, Systemic of Unspecified Sites). A requestor noted this “discontinuity” and stated that it would be “clinically appropriate” for all five diagnosis be assigned to MDC 05.

CMS agreed with the requestor and has proposed to reassign ICD-10-CM diagnosis code B33.24 from MDC 18 MS-DRGs 865 and 866 (Viral Illness with and without MCC, respectively) to MDC 05 in MS-DRGs 314, 315, and 316 (Other Circulatory System Diagnoses with MCC, with CC, and without CC/MCC, respectively).

Potential Impact of Viral Cardiomyopathy Proposal

In FY 2019, CMS paid sixteen claims with viral cardiomyopathy (B33.24) coded as the principal diagnosis. Specifically, CMS paid:

  • $109,042.08 for 13 MS-DRG 865 (Viral Illness with MCC) claims, and
  • $12,218.67 for 3 MS-DRG 866 (Viral Illness without MCC) claims.

As noted above, CMS’ proposal would move Viral cardiomyopathy from a DRG pair (MS-DRGs 865 and 866) with a two way severity split (with and without MCC) to a MS-DRG Group (MS-DRGs 314, 315, and 316) with a three way severity split (with MCC, with CC, and without CC/MCC). To estimate the financial impact, I took the conservative approach to calculate the difference in payment for the three MS-DRGs without MCC as if they also did not have a CC. Based on the national average payment, the shift in DRG assignment would equate to a net increase in payment for these sixteen claims of $34,535.43.

Note, there are several other changes being proposed, for example:

  • A proposal related to surgical ablations for Atrial fibrillation (AF) to revise the surgical hierarchy in MDC 05 to sequence MS-DRGs 231-236 (Coronary Bypass) above MS-DRGs 228 and 229 to enable a more appropriate MS-DRG assignment for these cases, and

    • A proposal to add three procedure code combinations describing removal and replacement of the right knee joint that were inadvertently omitted to the MS-DRGs that the same procedure combinations currently sequence to for the left knee (MS-DRGs 461, 462, 466, 467, and 468 in MDC 08 and MS-DRGs 628, 629, and 630 in MDC 10).

      I encourage key stakeholders take the time to review the proposed rule and remember that CMS is accepting comments on the proposed rule through 5 p.m. EDT on June 28, 2021.

      • CMS FY 2022 IPPS Proposed Rule CMS Fact Sheet:(link)
      • CMS FY 2022 Proposed Rule web page: (link)
Article Author: Beth Cobb, RN, BSN, ACM, CCDS
Beth Cobb, RN, BSN, ACM, CCDS, is the Manager of Clinical Analytics at Medical Management Plus, Inc. Beth has over twenty-five years of experience in healthcare including eleven years in Case Management at a large multi-facility health system. In her current position, Beth is a principle writer for MMP’s Wednesday@One weekly e-newsletter, an active member of our HIPAA Compliance Committee, MMP’s Education Department Program Director and co-developer of MMP’s proprietary Compliance Protection Assessment Tool.

This material was compiled to share information.  MMP, Inc. is not offering legal advice. Every reasonable effort has been taken to ensure the information is accurate and useful.