Transcript Standardized Infection Ratio

STANDARDIZED INFECTION RATIO
SIMPLIFIED
Laurie Fish, RN, BSN, CIC
Standardized Infection Ratio
• The SIR is a summary measure used to compare
the HAI experience among one or more groups of
patients to that of a standard population.
• Groups can be in various units of measure (unit,
hospital, state or country)
• The data in the group is aggregated into a
summary measure and then compared to the
standard population
Definition of SIR
The number of observed infections in
an index group divided by the number
of infections expected in that group,
based on a standard population.
This is the number
of HAIs in your
hospital
This is the estimated
number for your
hospital based on
standard population
Observed (O) HAIs
Expected (E) HAIs
= SIR
Standard Population
Standard Population for
CLABSI is 2006-2008
Standard Population for
CAUTI is 2009
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How does my facilities performance
compare?
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Making Comparisons
Your expected is
determined using the
following formula:
standard population
rate/1000 X your device
days= Expected
Your actual
(observed)
number is then
divided by your
expected= SIR
How is the CLABSI SIR calculated?
The national rate of CLABSI
for a teaching medical
surgical unit is 2.1/1000 cath
days
Hospital A Data:
Org
id
Location
Summary
Yr/Half
Months
Infcount
Number
expected
1001
8
ICU
2009H1
3
2
1.785
Central
line
days
850
SIR
SIR P
Value
1.12
0.532
7
95%
Confidence
Interval
0.199-3.527
The E for ICU = (2.1/1000) X 850 = 1.75
SIR = 2/1.785 = 1.12
Expected less than 1
If the expected is less that 1, a SIR will not
be calculated.
If the expected is less than 1 your denominator is too
low to calculate a precise SIR
How is SIR Calculated at hospital level?
Type of ICU
# of
# of
CLABSI central
line days
CLABSI
Rate
NHSN
Rate
p value
Expected
# of
CLABSI
Medical Cardiac
2
380
5.26
2.0
0.09
0.76
Medical
1
257
3.89
2.6
0.15
0.67
Med/Surgical
3
627
4.78
1.5
0.11
0.94
Neurosurgical
2
712
2.81
2.5
0.32
1.78
Total
8
1976
4.05
4.15
Overall CLABSI SIR= Observed/Expected= 8/4.15=1.93
Interpretation of the SIR
• During the first 6 months of 2012, there was 1 CLABSI identified in our facility
and we observed 2945 catheter days.
• Based on the 2006-2008 data we expected 4.442 CLABSIs
• This results in a SIR of 0.225 (almost 80% better than expected)
• The p value and 95% confidence interval indicates the number of observed is
not significantly lower that expected.
Interpretation of statistical tests
• p value: <0.05 is
considered
statistically
significant
• Confidence Interval:
if the range between
the 2 numbers does
not contain 1 the
value is considered
statistically
significant.
SIR Value of 1
0.5-1.5
1.2-2.0
0.7-1.5
0.1-0.5
0.5-1.2
Risk Adjustment: CLABSI and CAUTI
Population level risk
adjustment:
1. Patient mix by type of
unit location
2. Hospital affiliation
with a medical school
3. Bed size for the
patient care location
Risk Adjustment for Surgical Site Infection
Includes only deep and organ space and are
detected through readmission to the same
hospital
• Colon: Age, ASA, duration, endoscope, medical
school affiliation, bed size, wound class
• Abdominal hysterectomy: Age, ASA, duration of
procedure, hospital bed size
The SIR is not….
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Questions?