Clinical documentation
CC vs MCC: How One Diagnosis Changes the MS-DRG (and the Payment)
In the MS-DRG system, two patients with the same principal diagnosis can land in very different payment tiers based on a single secondary diagnosis. That secondary diagnosis — a CC or an MCC — is often the difference between two DRGs whose relative weights differ by nearly 2×.
On this page
What is a CC and an MCC?
Medicare classifies secondary diagnoses by how much extra care they typically require:
- CC — Complication or Comorbidity: a secondary condition that meaningfully raises resource use (for example, many types of acute infection or exacerbated chronic disease).
- MCC — Major Complication or Comorbidity: the most severe tier — conditions such as acute respiratory failure, severe sepsis with septic shock, or acute organ failure.
Most MS-DRG "families" come as a severity split: a base condition divides into a with-MCC, with-CC, and without-CC/MCC DRG. The grouper assigns the highest tier supported by a valid, documented secondary diagnosis.
Worked example: sepsis (FY2026)
Septicemia without mechanical ventilation >96 hours splits into two MS-DRGs by MCC status. Here are the actual FY2026 relative weights:
| MS-DRG | Description | Relative weight |
|---|---|---|
| 872 | Septicemia/severe sepsis without MCC | 1.0233 |
| 871 | Septicemia/severe sepsis with MCC | 1.9425 |
| Impact | 871 ÷ 872 | 1.90× |
When an MCC such as severe sepsis with septic shock (R65.21) or acute respiratory failure is documented and coded, the case groups to DRG 871 — carrying roughly 1.9× the relative weight of DRG 872, and therefore roughly 90% more payment for the same underlying admission. Because a DRG payment is the relative weight × the hospital's IPPS base rate, the exact dollar swing scales with the hospital.
Accuracy, not upcoding. The goal of clinical documentation improvement (CDI) is to capture the severity that is clinically present and documented — not to inflate it. A missed but valid MCC understates the patient's acuity and under-reimburses the care actually delivered; an unsupported one is a compliance risk. The right answer is the DRG the record supports.
Why it matters for accuracy and quality
- Accurate assignment: an unqueried, missing MCC quietly leaves the case in the lower-weighted DRG.
- Severity & mortality profiling: DRG severity feeds risk-adjusted quality metrics; under-coding makes outcomes look worse than they are.
- Auditability: the CC/MCC must be a valid secondary diagnosis supported by the record — and it must survive the POA check.
One important caveat: a CC/MCC only earns the higher DRG if it counts. Under Medicare's Hospital-Acquired Conditions program, a complication that developed during the stay can be stripped out — see POA indicators and MS-DRG reimbursement.