Surveillance of nosocomial infections
Johnny, Courtesy, Brocolli
Nosocomial infections (NCI)
"nosus" = disease
"komeion" = to take care of
Infections that occur during hospitalization
but are not present nor incubating upon
hospital admission
Characteristics of hospitals
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Treatment is main focus
Many stakeholders
Shift work
A lots of data, easily defined cohorts
Different patient population
Variation of length of stay
Vulnerable patients
Community vs. hospital
The problem of NCI
USA
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–
Urinary tract infections: 2.4 per 100 admissions
Pneumonia: 1 case per 100 admissions
Surgical site infections: 2.8 per 100 operations
NCI; one death every 6th minutes
Norway
– One of 19 patients have a NCI
The problem of NCI
• Regional hospital, Zimbabwe:
– 1 of 6 developed SSI
• 2 referral hospitals, Ethiopia:
– 38.7% developed SSI
– 14 of 18 deaths attributed to SSI
Cost of NCI
England
• Average cost per NCI: 3.000 pounds
• Extra days:
Urinary tract infections:
Pneumonia:
Surgical site infections:
6
12
7
Why surveillance?
• NCI cause of morbidity and mortality
• One third may be preventable
• Surveillance = key factor
– an infection control measure
– overview of the burden and distribution of NCI
– allocate preventive resources
• Surveillance is cost-efficient!!
The surveillance loop
Health care
system
Surveillance
centre
Reporting
Data
Action
Information
Feedback,
recommendations
Analysis,
interpretation
Event
Considerations when creating a
surveillance system
• Goal of the surveillance system (why)
• Engage the stakeholders (who)
• Surveillance method (what, how, when)
– definition
– what to collect
– how to collect (operation of system)
• Available resources
I may not have gone where I intended to go,
but I think I have ended up
where I needed to be
Douglas Adams
Objectives
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Reducing infection rates
Establishing endemic baseline rates
Identifying outbreaks
Identifying risk factors
Persuading medical personnel
Evaluate control measures
Satisfying regulators
Document quality of care
Compare hospitals’ NCI rates
Who
• All hospitals?
• All departments?
• All specialties?
• Other health institutions?
Stakeholders
Central
adm.
…..
Local
adm.
Public
Health
instituteI
ICP
Itdep.
Directorat
Surveillance of
surgical site infections
Ministry
Of health
Surgical
wards
Service
dep.
Surgical
ward. 2
Lab
Patients
Surveillance of one or more types of NCI
Urinary tract infections
Lower respiratory tract infections
Surgical site infections
Bloodstream infections
Conjunctivitis
Others…
Targeted surveillance
• Special patient population
(surgical, medical, paediatric, intensive)
• Diagnostic and therapeutic procedures
(endoscope, haemodialysis, catheterization,
blood transfusion)
• Specific pathogens
(staphylococcus aureus, MRSA,
clostridium difficile, norovirus)
Variables
• Administrative data
– Id, address, dates of admission, discharge..
• Patient related factors:
– Age, sex, severity of underlying disease
• Procedures
– Surgery
– Devices (e.g. catheters)
• Treatment, diagnosis
– Use of antibiotics
……
Stratification points,
surgical site infections
Variables for stratification
Risk index
Stratification points
ASA score
>2
1
Duration of operation
> 75 percentile
1
Wound classification
Contamination class > 2
1
Endoscopic procedure
-1
When?
• During hospital stay?
– Frequency of data collection
• After discharge?
– When and how?
How?
• Two main surveillance methods
– incidence
– prevalence
• Variations within these methods
Incidence (cohort) studies
marching towards outcomes
Cohort design
Prospective
NCI
Exposed
PAR
T
Not NCI
Study
group
Not exposed
T
NCI
Not NCI
NCI
PAR =
Population at Risk
T
Time period
=
Retrospective
Measure
• Percentage
– #NCI / # patients
• Incidence density
– Patient-days as denominator
• Risk factors
RR=
risk in patients exposed
risk in patients not exposed
Positive aspects
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Provide information on several risk factors
Exposure measures before outcome
Information on consequences of NCI
Can identify outbreak
Ongoing attention
Limitations
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Resource demanding
Loss of follow-up
Seldom NCI
Confounding and bias is possible
Prevalence
• Measures number of current NCI
• Within a defined population at risk
• At a given time
• #NCI / #patients at risk *100
• Point or period prevalence
Time of survey 20.10 at 8 AM …………… Name of institution …Oslo hospital……..………………………………..
Contact person ……Hanne Eriksen……………………………… Phone………………22042625……………………
Fax …22330033………………………………………………..… E-mail……[email protected]……..….………………..
Region: Oslo…………………………
Department
Number of Number of
patients at patients
8 AM
operated
Number of Number of Number of
urinary
pneumonia surgical site
tract inf.
inf.
Number of
bacteremia
Number of Total
patients on prevalence
antibiotic
(%)
Rehabilitation
50
15
1
1
0
0
25
4,0
Surgical unit
80
3
2
0
4
0
7
7,5
Medical unit
50
0
4
1
0
0
5
10
Paediatric unit
20
5
1
1
0
1
7
23
10
8
7
1
39
Total for
institution
Use of prevalence surveys
• Show trends
• Estimate
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distribution of NCI
surveillance accuracy
incidence from prevalence??
antimicrobial usage patterns
• Rise awareness
Limitations
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Do not identify causes
Duration of NCI affects the prevalence
Not very suitable for small institutions
Difficult to adjust prevalence
Prevalence survey
Incidence surveillance
UTI n=6
SSI n=2
Define method
Identify and review
– Protocols used elsewhere e.g.
HELICS incidence, Norway's prevalence
– Literature
Minimum dataset
Methodological issues
• Definitions
NCI
– Cut off 48 or 72 hours?
– Criterias from Centers for Disease Control and Prevention (hospital)
– McGeer (long-term care facilities)
Risk variables
• Case finding
– Active or passive
– By whom?
– After discharge?
– Prospective or retrospective?
Case finding
• Active: by surveillance personnel
• Passive: by medical personnel
• Laboratory or clinical based
• Source of data
– Clinical examinations
– Medical records, reports from laboratories
– Forms or interviews
Ongoing systematic collection?
• Cohort
– Continual?
– Periodical?
• Prevalence
– Weekly?
– Yearly?
– Depends on objectives
Precision of estimate
Number of patients
under surveillance
50
100
100
200
1000
3500
8000
Number of Incidence (%) 95% confidence
NCI
interval
3
6% (1,3% - 17%)
3
3% (0,6% - 8,5%)
5
5% (1,6% - 11%)
20
10% (6,2% - 15%)
50
5% (3,7% - 6,5%)
100
3% (2,3% - 3,5%)
320
4% (3,6% - 4,5%)
Dummy table
Variable
Antibioticprophylaxis
Yes
No
Stratified points
1
2
3
Etc.
Insidence%
95%
confidence
interval
Relative
risk
4,6% (4,1% (300/6500) 5,2%)
10% (8,8% - 12%)
(150/1500)
Reference
5,0%
(350/7000)
7,1%
(50/700)
16,7%
(50/300)
Reference
(4,5% 5,5%)
(5,9% 8,4%)
(14%-19%)
95%
confidence
interval
2,2 (1,8-2,6)
Relative
risk
95%
confidence
interval
Reference
2,1 (1,7-2,5)
Reference
6,0 (4,8 – 7,5)
6,2 (5,0 – 7,4)
10 (8,1 – 12)
9,4 (8,0 – 11)
Implementing surveillance system
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Administrators responsibility
Involvement of stakeholders
Identify available resources
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Personnel
Money
Time
Equipment
It- solutions
Realistic project plan
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Organization map
Making forms and letters
It-solutions
Training
Use of data
Making surveillance work
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Support by the administrators
Involve local experts
Simple
Minimize resources required by hospitals
Training
Feedback and use of data
Flexibility
Training topics
• Why surveillance?
• How?
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Definition
Case finding
Case studies
It-solution
• Use of data
Quality controls
• Define acceptable loss of follow-up
• Make sure all patients are included
• Identify infections
– Use several sources
– Compare data, conduct surveys
– Training
• “Clean” data
– Completeness
– Logical values
Use of data
• Prevent NCI
• Ward audits
• Present data to hospitals, administrators,
MoH, patients
• Argument for resource allocation
• Audits for medical personnel
• Raise awareness
Incidence of SSI over time
Conclusion
Hospital
Pathogen
Hospital
Surveillance Happy
Patients
Unhappy
patients
Unhappy
director
Happy
director