# SIR Presentation

Document Sample

```					   Sharing and explaining the
standardized infection ratio (SIR):
words, colors, and/or δymβφĨs?

Dana Burshell, MPH, CPH, CIC
HAI Epidemiologist
Virginia Department of Health
What is a standardized infection ratio?
• The standardized infection ratio (SIR) is a
summary measure used to track healthcare-
associated infections (HAIs) at a national, state,
or local level over time. The SIR adjusts for
patients of varying risk within each facility.

- The National Healthcare Safety Network (NHSN)
The SIR calculation
• In HAI data analysis, the SIR compares the actual
number of HAIs reported (observed) with the
baseline U.S. experience (expected/predicted),
adjusting for several risk factors that have been
found to be significantly associated with
differences in infection incidence.
SIR = number of observed (O) CLABSIs
number of expected (E) CLABSIs
– NHSN aggregate data are used as the standard
population and considered the baseline U.S. experience
– NHSN baseline data used in an SIR are used to calculate
the expected or predicted number of HAIs adjusting for
the identified risk factors.
What does the SIR number mean?
• Accounting for differences in the types of patient
followed:
– An SIR greater than 1.0 indicates that more HAIs were
observed than predicted.
– An SIR less than 1.0 indicates that fewer HAIs were
observed than predicted.
– An SIR equal to 1.0 indicates the same number of
HAIs were observed than predicted.

• However, the SIR alone does not imply statistical
significance.
Statistical significance of the SIR:
P-value and 95% confidence intervals
• The SIR is only a point estimate and needs additional
information to indicate if it is statistically significantly
different from 1.
• A 95% confidence interval (CI) and a p-value are calculated
by NHSN for each SIR and determines statistical
significance.
– A 95% CI assesses the magnitude and stability of an SIR.
Therefore, a 95% CI is the range of estimated SIR values that
has a 95% probability of including the true SIR for the
population.
– If the 95% CI does not contain the value 1, the SIR is
"statistically significant".
– If the p-value is less than 0.05, the SIR is “statistically
significant".
Explaining and interpreting the SIR: Virginia data
Summary      CLABSIs      CLABSIs      Central line
SIR     p-value     95% CI
Time Period observed (#) expected (#)    days (#)
2011Q3         58          87.323        46,058      0.664   0.0006    0.504, 0.859

• During the third quarter of 2011, there were 58 CLABSIs identified and
46,058 central line days observed in Virginia adult intensive care units.
• Based on the NHSN 2006-2009 baseline data and the composition of
locations in Virginia facilities, 87.323 CLABSIs were expected.
• This result is an SIR of 0.664 (O/E= 58/87.323), signifying that during this
time period, Virginia facilities identified 34% fewer CLABSIs than expected.
• The p-value (0.0006) and 95% confidence (0.504, 0.859) interval indicate
that the number of observed CLABSIs is statistically significantly lower
than the number of expected CLABSIs. (Reminder: If the p-value is less
than 0.05 and the 95% CI does not cross 1, the SIR is statistically
significant.)
What does a significant SIR mean?
• While in many cases, significantly high SIRs may
reflect a need for stronger prevention efforts for
the given type of infection and significantly low
SIRs may support already existing strong
prevention efforts for that infection type, several
other factors such as validation of reported data
may play a role.
• The real measure of success will come when SIRs
can be followed over time to indicate if positive
progress occurs and is sustained. The ultimate
goal is zero HAIs, so efforts are never complete.
Central line-associated bloodstream infection (CLABSI)
standardized infection ratio (SIR) by quarter,
Virginia adult intensive care units, 2009-2011
0.9
Standardized Infection Ratio (SIR)

0.8
using Excel to
0.7                                        visually show
0.6                                        overall decrease
0.5                                        over time
0.4                                          SIR
0.3   Line graph of                          Linear (SIR)
0.2   SIR point
0.1   estimates
0

• Since 2009, Virginia facilities have identified fewer CLABSIs than expected in adult ICUs,
reflecting already existing strong infection prevention efforts.
• Although there is not a consistent decrease in SIR from quarter to quarter, the overall trend
since 2009 has been a downward one.
• Because the ultimate goal is sustaining zero CLABSIs, individual hospitals should continue
effective prevention efforts and identify and address areas for improvement when they occur.
How to generate NHSN SIR outputs
“Analysis” --> “Generate Data Set” --> “Generate New”
(note: this will take some time to load)
3. Click “Analysis” --> “Output Options”
4. On the white screen, click “Device-Associated Module”
--> “Central Line-Associated BSI” --> “CDC Defined
Output” --> “SIR – In-Plan CLAB Data”
5. Select “Run” for data aggregated by 6-month intervals
and CDC location type or select “Modify” to customize
the output
How can I visually display SIR data?
SIR data presentation: Components to consider
Stratification type
Presented data            Format                                  Interpretation
and time period
• # infections        • Format              • Aggregate by        • Cues
• # CL days             • Table               • Hospital            • Color
• Rate                  • Bar graph           • Adult/PICU          • Symbols
• p-value           • Order                   and NICU            • Words
• SIR                   • Alphabetical        • Unit              • SIR Language
• # expected          • By SIR (if same   • Time period           • Expected
• p-value               SIR, by number      • Annual              • Predicted
• 95% CI                of CL days)         • Semi-annual       • SIR language (as
• Comparison        • Considerations        • Quarterly           significantly
• National          • No infections                             related to 1)
• State             • <1 expected                               • Better/lower
• Hospital                                                      • No different/
same/similar
• Historical data
• Worse/higher

Always customize for your audience whenever possible.
The following slides show how some states
have included certain SIR and visual
components for public reporting:

• Which components do you think are
important?

• Which examples would be most useful for you
and the audiences within your settings?
Table (color and words)
New Hampshire

† = Less than 1 HAI expected
Summary table (words)
Maryland
Table (color and symbols)
Maryland: Chosen by and designed for consumers
Horizontal bar graph (color and visual)
Maryland: Chosen by and designed for clinicians
Horizontal bar graph (color, visual)
Tennessee comparison to national and state rates
Horizontal bar graph (color, visual)
Tennessee
Vertical bar graph (visual)
Tennessee

ICU type
Vertical bar graph (visual):
Tennessee comparison to state SIR

ICU type
Horizontal bar graph (color, visual)
Virginia explores the SIR

More infections than expected   Observed number of infections     Fewer infections than expected
(statistically significant)   similar to expected                   (statistically significant)
(not statistically significant)
No infections
Building your SIR report: Choosing components

• Research shows that when healthcare facilities
are aware of their infection issues and implement
concrete strategies to prevent them, rates of
certain hospital infections can be decreased by
more than 70 percent.
• Infection data can give healthcare facilities,
patients, and public health agencies the
knowledge needed to design and implement
prevention strategies that protect patients and
save lives.
Benefits of Data Presentation
• Increase awareness of HAIs
• Feed back data to those who can make a
difference
• Provide benchmark data to support
improvement initiatives
• Keep HAIs in the spotlight
Resources
• CDC's National Healthcare Safety Network
(NHSN) Healthcare-associated Infections
Summary Data Reports Q and A
– http://www.cdc.gov/HAI/surveillance/
QA_statesummary.html

• NHSN e-News: SIRs Special Edition
NHSN_NL_OCT_2010SE_final.pdf
Data quality resources
http://www.cdc.gov/nhsn/PDFs/pscManual/NHSN-

• Helpful Tips for CLABSI Reporting for the Centers for
Medicare and Medicaid Services’ Hospital Inpatient
Quality Reporting Program (CMS Reporting Program)