Clinical Takeaway
- CMS SEP-1 still uses SIRS-based criteria for sepsis and defines septic shock without requiring vasopressors.
- Sepsis-3 and SSC 2021 define sepsis as infection with organ dysfunction and septic shock as hypotension requiring vasopressors plus lactate >2 despite fluids.
- This mismatch explains why patients may meet CMS criteria yet not align with current consensus definitions, creating challenges in both bedside care and reporting.
| Category | Sepsis-2 (2001) | CMS SEP-1 (2015 – still active) | Sepsis-3 (2016) | SSC 2021 |
|---|---|---|---|---|
| Sepsis | Suspected infection plus ≥2 SIRS criteria | Suspected infection plus ≥2 SIRS criteria | Suspected infection plus organ dysfunction (SOFA ≥2) | Same as Sepsis-3; emphasizes early recognition as a medical emergency |
| Severe Sepsis | Sepsis plus organ dysfunction, hypoperfusion, or hypotension | Sepsis with organ dysfunction (examples: lactate >2, creatinine >2, bilirubin >2, platelets <100k, INR >1.5) | Eliminated (organ dysfunction included under “sepsis”) | Still eliminated |
| Septic Shock | Sepsis with hypotension persisting after fluids, with perfusion abnormalities | Hypotension not responsive to fluids, or lactate ≥4 mmol/L (vasopressors not required) | Vasopressors required to maintain MAP ≥65 mmHg and lactate >2 mmol/L despite fluids | Same as Sepsis-3; urgency emphasized |
| Screening Tools | SIRS | SIRS (per quality reporting) | SOFA/qSOFA focus; qSOFA has limited sensitivity | Recommends against qSOFA alone; favors SIRS, NEWS, or MEWS |
| Notes | Introduced SIRS into sepsis definitions | Federal quality measure (pay-for-reporting in 2015; moving to pay-for-performance in 2026) | International consensus redefining sepsis | Clarified screening, fluids, vasopressors, and antibiotic timing |
Although Sepsis-3 redefined sepsis as infection with organ dysfunction and removed the term severe sepsis, the CMS SEP-1 quality measure continues to use older SIRS-based language. This misalignment has created ongoing confusion for clinicians, since CMS definitions remain tied to reimbursement and performance metrics. For example, under CMS, any infection with organ dysfunction or lactate >2 mmol/L qualifies as severe sepsis, and septic shock may be diagnosed with hypotension unresponsive to fluids or lactate ≥4 mmol/L, even if vasopressors are not required. In contrast, Sepsis-3 and the 2021 Surviving Sepsis Campaign emphasize organ dysfunction, recognize sepsis as a medical emergency, and define septic shock by vasopressor requirement plus elevated lactate despite resuscitation. These differences highlight why patients may meet CMS criteria while not fulfilling Sepsis-3 definitions, and why bedside management and regulatory reporting can feel out of step.
Further Reading
Updates and Controversies in the Early Management of Sepsis and Septic Shock August, 2025
Sam Ashoo, MD, FACEP, is board certified in emergency medicine and clinical informatics. He serves as EB Medicine’s editor-in-chief of interactive clinical pathways and FOAMEd blog, and host of EB Medicine’s EMplify podcast. Follow him below for more…
