Surgical Site Infection (SSI)
A Surgical Site Infection (SSI) is an infection occurring after surgery in the part of the body where surgery took place, classified by CDC/NHSN as superficial incisional, deep incisional, or organ/space, and tracked as a CMS hospital-acquired condition affecting Medicare payment.
What is a Surgical Site Infection?
The CDC and NHSN define SSIs across three depth classifications: superficial incisional (skin and subcutaneous tissue), deep incisional (fascia and muscle layers), and organ/space (any part of the anatomy opened or manipulated during surgery). NHSN mandates SSI surveillance reporting for specific high-volume procedure categories: colon surgeries (COLO), abdominal hysterectomy (HYST), knee arthroplasty (KNEO), hip arthroplasty (HPRO), and cesarean section (CSEC). Performance is measured via the Standardized Infection Ratio (SIR) — observed SSIs divided by predicted SSIs based on the NHSN national risk model. An SIR below 1.0 indicates better-than-average performance. Key modifiable risk factors include diabetes with A1C above 7.5 (doubling SSI risk), obesity with BMI above 35, smoking, and immunosuppression. Prevention protocols target prophylactic antibiotic administration within one hour before incision, appropriate skin prep, normothermia maintenance, and perioperative glucose control.
Why It Matters for Healthcare Analytics
Each SSI adds an average of $20,000–$30,000 to episode cost through extended hospital stays, reoperation, and readmissions. SSI SIR contributes to Domain 2 of the CMS HAC Reduction Program score, meaning hospitals in the bottom quartile nationally face a 1% Medicare payment reduction on all inpatient claims. Identifying procedure-level SIR outliers and correlating them with surgeon technique, antibiotic timing compliance, and patient risk factors is essential for targeted quality improvement.
How Vizier Tracks SSIs
Upload your NHSN SSI surveillance data and surgical case records, then ask "What is our COLO SSI SIR compared to the national benchmark this quarter?" — Vizier calculates SIR by procedure type, identifies surgeon-level outliers, and flags antibiotic timing compliance gaps driving elevated infection rates.