Using and Sharing Findings from Surveillance:

Rates, Ratios Proportions, Data Display & OUTBREAKS

Russ Olmsted, MPH, CIColmstedr@trinity-health.org

Reporting HAI Data; Definitions

Larger size image on document at end of this section see also: Lee TB, et al Recommended practices

Incidence rate (“incidence density”)

Number of new cases –––––––––––––––––––––––––––––––Avg. population at risk × Time interval

Number of new cases = ––––––––––––––––––––

Population-time

Prevalence; another important measure

Number of existing (new + old) cases

Prevalence = –––––––––––––––––––––––––––– Population at risk

Often expressed as a proportion

Population at risk

Existing cases: Prevalence

Outcomes

Incident cases: number of kernels popped as heat is applied

Kernals that go unpopped = not susceptible

Incidence and Prevalence• Incidence and prevalence measure different

aspects of disease occurrence Prevalence Incidence

Numerator:

Denominator

Measures:

Most useful:

All cases, no matter how long diseased

Only NEW cases

All persons in population

Only persons at risk of disease

Presence of disease

Risk of disease

Resource allocation

Risk, etiology

Device Utilization Ratio• Device utilization ratio (DUR) is the

proportion of patient or resident days for which a certain device is used

• DUR is specific to one device;e.g. central line, urinary catheter

• DUR reflects the amount of devices used and can be a reflection of patient severity or over utilization

Standardized Infection Ratio (SIR)– Observed # of HAIs

• SIR = ------------------------------------------------- – Expected (Predicted) # of HAIs

• Observed # of HAI – the number of events identified from surveillance HAIs

Expected or predicted # of HAI – comes from national baseline data, e.g. NHSN

Who’s Using SIR? CMS http://www.medicare.gov/hospitalcompare/se

arch.html

PERFORMANCE MEASURES:

ProcessExamples of process measures:

1) Compliance with educational program: calculate percent of personnel who have proper training on urinary cath. insertion

# persons who insert catheters and are trained

__________________________________ # personnel who insert urinary catheters Multiply by 100 to express as percent

Examples of other Uses of Process Measures

Hand Hygiene (HH) Adherence:

Numerator: # of Instances HH was used___________________________________ X 100

Denominator: # of opportunities for HH

++++++++++++++++++++++++++++++++++++++++++++++++++++

PERFORMANCE MEASURES

3. Compliance with documentation of indication for catheter placement

# number of patients on unit with catheter & proper documentation of indication

____________________________________# of patients on unit with catheter

• Multiply by 100 to express as percent

Outcome Measures

Incidence DensityDevice-associated (DA) rates are calculated as Incidence Density

Rates (IDRs) What is an “Incidence Density Rate”?Numerator = # of new cases during a period of timeDenominator = person-time or device day during -same time X a constant, e.g. 100, 1000, or 10,000

Outcome Measures, cont.Recommended outcome measures:

1. Rates of CAUTI – based on surveillance definitions

# of cases of CAUTI ______________________________total # of urinary-catheter days

• Multiply by 1000 to express as # infections per 1000 catheter days

Sharing & Displaying Data

PA Patient Safety Advisory, 2010

Trend Analysis; CDI rates by reporting Quarter

Cumulative CDI rates [community-onset + hospital onset] MDCH. SHARP Michigan 2012 Quarter 4 HAI Surveillance Report

Trend Analysis; CDI rates by reporting Quarter

Cumulative CDI rates [community-onset + hospital onset] MDCH. SHARP Michigan 2012 Quarter 4 HAI Surveillance Report

Distribution of LabID CDI by type

Cumulative CDI rates [community-onset + hospital onset] MDCH. SHARP Michigan 2012 Quarter 4 HAI Surveillance Report

Display of SIRTN Report on HAIs, June 2012

Larger size image on document at end of this section

Description of Outbreaks, U.S. Hospitals

• 35% of 855 hospitals who completed a survey had investigated possible outbreak.

• Frequency = 1.3 investigations/facility/24 months• Triggers:

– unusual organism (38.1%); – rate above baseline for a specific HAI site or for a specific unit

were also frequent triggers (27%) • Pathogens:

– Norovirus (18.2%)– Staphylococcus aureus (17.5)– Acinetobacter spp (13.7)– Clostridium difficile (10.3)

Rhinehart E, et al. AJIC 2012

Date of download: 10/19/2012Copyright © 2012 American Medical

Association. All rights reserved.

From: Hospitalizations and Mortality Associated With Norovirus Outbreaks in Nursing Homes, 2009-2010

JAMA. 2012;():1-8. doi:10.1001/jama.2012.14023

aFor norovirus outbreaks, outbreaks were counted as occurring during the week the first ill case was noted to be symptomatic.

308 Nursing Homes reported Oubreaks, Jan.2009-Dec. 2010

>67,000 hospitalizations; 26,000deaths

Operational Definition of Outbreak/Cluster

• Occurrence of more cases of disease than expected in a given area among a specific group of people over a particular period of time

• Example: cluster of acute gastroenteritis cases is detected in the healthcare facility

Prevention and Control Measures: Influenza in LTCFs

Control of Influenza Outbreaks in Long-Term Care Facilities

• Definition of Cluster: Three or more cases of acute febrile respiratory illness (AFRI) occurring within 48 to 72 hours, in residents who are in close proximity to each other (e.g., in the same area of the facility).

• Outbreak: A sudden increase of AFRI cases over the normal background rate or when any resident tests positive for influenza. One case of confirmed influenza by any testing method in a long-term care facility resident is an outbreak.

– http://www.cdc.gov/flu/professionals/infectioncontrol/longtermcare.htm

Steps of an outbreak investigation

• Confirm outbreak and diagnosis !• Define case • Identify cases and obtain information• Descriptive data collection and analysis• Develop hypothesis• Analytical studies to test hypotheses• Special studies• Communication, including outbreak report

Imp

lemen

t con

tr ol m

easures

Role of the Infection Preventionist

• Identification of risk factors

• Identification of emergency control/long term interventions

• Documentation

• Best practice identification

0

10

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30

40

50

60

70

80

90

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39

DAY

CASES

Confirmation

Outbreak Detection and Response

Detection/Reporting

First Case(s)

First ResponseLong term controls

Evaluation

Describe the casesDescriptive epidemiology

-Who is sick?-Where are they (unit, city, etc.)-When did they become ill?-What were they exposed to?

Person

Place

Time

Cases

0102030

1 2 3 4 5 6 7 8 9 10

0

500

1000

1500

Age Group

Evaluate information

Pathogen? Source? Transmission?

Note: Line listing may also be used for routine surveillance of HAIs.