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The Standardized Infection Ratio The Standardized Infection Ratio

The Standardized Infection Ratio - PowerPoint Presentation

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The Standardized Infection Ratio - PPT Presentation

Steven P Hudson MBA MA Statistician Health Care Excel Inc Objectives Describe what the Standardized Infection Ratio SIR is and how it is calculated   Explain how to generate and interpret a report utilizing the SIR ID: 559915

number sir infection data sir number data infection expected observed population nhsn risk national hais standard infections predicted ssis

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Slide1

The Standardized Infection Ratio

Steven P Hudson, MBA, MA

Statistician

Health Care Excel, IncSlide2

Objectives

Describe what the Standardized Infection Ratio (SIR) is and how it is calculated.

 

Explain how to generate and interpret a report utilizing the SIR.

 

 Slide3

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) Slide4

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.

number of

observed (O) number of expected (E)NHSN aggregate data are used as the standard population and considered the baseline U.S. experienceNHSN baseline data used in a SIR are used to calculate the expected or predicted number of HAIs adjusting for the identified risk factors.

SIR=Slide5

What does the SIR number mean?

Accounting for differences in the types of patient followed:

A SIR

greater than 1.0

indicates that

more

HAIs were observed than predicted.

A SIR less than 1.0 indicates that fewer HAIs were observed than predicted.A SIR equal to 1.0 indicates the same number of HAIs were observed than predicted.However, the SIR alone does not imply statistical significance.Slide6

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 a SIR. Therefore, a 95% CI is the range of estimated SIR values that have 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.”Slide7

Statistical Significance

If the p-value is less than .05, then your rates are different than the national average

If the confidence level does not overlap 1, then your rates are different than the national average.Slide8

I was just getting used to rates, why the SIR?

More sensitive for low denominators

Ability to combine data

Useful for predicting state and national ratesSlide9

OK , I’m no statistician-what’s all this mumbo jumbo about?

In simple terms- you are compared to the average of a referent population and adjusted for risk

In this case, it is a historical control.

The SIRSlide10

Calculation

Observed (

actual number of Infections

)

Expected (

expected number of infections)SIR= Slide11

Let’s take a closer look

Hospital A :

Type of ICU

Number

of Infections

Line days

My

rateNHSN MeanMed/ Surg1865

1.1

2.1

SICU

0

1000

0

2.8

CCICU

2

948

2.1

1.1

MICU

2

1000

2.0

2.1Slide12

Turned into SIR

Type of ICU

Number

of infections

Number expected

SIR

Observed/

expectedP VALUEMed/ Surg10.951.05SICU02.8

0

CCICU

2

0.93

2.1

MICU

2

2.1

0.95

SIR is less than 1Slide13

Simply

Put

A SIR of

1.0

 means the observed number of infections is equal to the number of expected infections.

A SIR

above 1.0

means that the infection rate is higher than that found in the "standard population." For HAI reports, the standard population comes from data reported by the hundreds of U.S. hospitals that use the NHSN system. The difference above 1.0 is the percentage by which the infection rate exceeds that of the standard population.

A SIR

below 1.0

means the infection rate is lower than that of the standard population. The difference below 1.0 is the percentage by which the infection rate is lower than that experienced by the standard population. Slide14

How to generate NHSN SIR outputs

Log into NHSN --> enter the Patient Safety Module

Starting from the blue navigation menu on the left, click “Analysis” --> “Generate Data Set” --> “Generate New” (note: this will take some time to load)

Click “Analysis” --> “Output Options”

On the white screen, click “Device-Associated Module” --> “Central Line-Associated BSI” --> “CDC Defined Output” --> “SIR – In-Plan CLAB Data”

Select “Run” for data aggregated by 6-month intervals and CDC location type or select “Modify” to customize the outputSlide15

Conducting your own analysisSlide16
Slide17
Slide18
Slide19

orgid=10330Slide20
Slide21

Surgical SIRSlide22

SSI SIRSlide23

SSI data are summarized like they are for CLABSIs:Slide24

Interpreting the SIR

During 2009, there were 524 procedures performed and 13 SSIs identified.

Based on the NHSN 2006-2008 baseline data 6.687 SSIs were expected.

This results in a SIR of 1.94 (13/6.687), signifying that during this time period our facility identified 94% more SSIs than expected.

The p-value and 95% confidence interval indicate that the number of observed SSIs is significantly higher than the number of expected SSIs.Slide25

The SIR

PROS

CONS

Surgical risk adjustment is a significant

improvement

Risk adjustment still suboptimal – especially with CLABSI data

Consistent

with other types of data such as mortalityNot designed to compare one institution to another- only to compare with national averageAdvantages with rare eventsPotential problems with ranking ,etcOverall rates can cloud the big pictureSlide26

Questions ?Slide27

Contact InfoEmail:

shudson@kyqio.sdps.org

502-454-5112 ext 2252

27

This material was prepared by Health Care Excel, the Medicare Quality Improvement Organization for Indiana, under contract with the Centers for Medicare & Medicaid Services (CMS), an agency of the U.S. Department of Health and Human Services. The contents presented do not necessarily reflect CMS policy. 10SOW-IN-INDPAT-13-012 4/1/13