Standardized Infection Ratio (NHSN, Observed Over Predicted)
The NHSN standardized infection ratio: observed infections divided by the predicted count from the facility's NHSN report.
Open the tool → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Observed infections
- 5
- Predicted infections
- 2.365
Result: SIR 2.114: more infections were observed than predicted (5 observed ÷ 2.365 predicted).
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Observed infections (whole number)
- Predicted infections (from the NHSN report)
How this is calculated
Citation
CDC National Healthcare Safety Network. The NHSN Standardized Infection Ratio (SIR): A Guide to the SIR, updated March 2024: the SIR as observed over predicted infections, and no SIR when fewer than 1.0 infections are predicted. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.