Reading a standardized infection ratio
Infection measures are not reported as a raw count or a simple percentage. CMS publishes a standardized infection ratio (SIR), which compares the infections a hospital actually had with the number that would be expected given its patient mix, the devices it uses and the procedures it performs.
- 1.00 — exactly as many infections as expected.
- Below 1.00 — fewer infections than expected. 0.50 means half as many.
- Above 1.00 — more than expected. 2.00 means twice as many.
The adjustment matters. A large teaching hospital running many ICU central lines will see more infections in absolute terms than a small community hospital, and comparing raw counts would punish it for treating sicker patients. The SIR is what makes the comparison fair.
Why small hospitals often show no infection data
A hospital that placed twelve central lines in a year cannot produce a meaningful infection ratio — a single infection would swing it wildly. CMS suppresses these results rather than publish noise, which is why so many smaller hospitals show "not reported" here.
The measures in this category
These are the measures CMS publishes in this category, with the national median across all reporting hospitals for context.
| Measure | Better is | National median |
|---|---|---|
| Bloodstream infections (CLABSI) Infections entering the blood through a central line. Reported as a ratio: 1.0 means as many infections as expected for this hospital's patient mix, below 1.0 means fewer. | Lower | 0.48 |
| Urinary tract infections (CAUTI) Infections linked to urinary catheters, as a ratio to the number expected. Below 1.0 is better than expected. | Lower | 0.40 |
| Surgical infections — colon surgery Infections at the surgical site after colon surgery. | Lower | 0.72 |
| Surgical infections — hysterectomy Infections at the surgical site after abdominal hysterectomy. | Lower | 0.81 |
| MRSA blood infections Bloodstream infections from MRSA, a staph bacteria resistant to common antibiotics. | Lower | 0.60 |
| C. diff infections Clostridioides difficile, an intestinal infection that often follows antibiotic treatment. | Lower | 0.28 |
| Hip/knee replacement complications Serious complications within 90 days of elective hip or knee replacement, such as infection or the need for a repeat operation. | Lower | 4.1% |
| Serious complications (composite) A combined score covering bedsores, falls with injury, collapsed lung, blood clots after surgery, and other avoidable harms. | Lower | Not enough hospitals report it |
Medians calculated by hospiguide.org from the current CMS release, across hospitals that reported each measure. We use the median rather than the mean because these measures are skewed — a handful of outliers pull an average far from the typical hospital.
Where to go next
Browse hospitals by state to see these measures for a specific hospital, or compare two hospitals side by side. For the official source, see Medicare.gov Care Compare.