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

• 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– 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: 6

Pneumonia: 12

Surgical site infections: 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

Event

Action

Data

Information

Health care system

Surveillance centre

Reporting

Feedback, recommendations

An

alysis, in

terpretation

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

• 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?

…..

PublicHealth

instituteI

Directorat

MinistryOf health

Service dep.

Lab Patients

Surgicalward. 2

Surgicalwards

It-dep.

ICP

Local adm.

Centraladm.

Surveillance of surgical site infections

Stakeholders

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

PAR = Population at Risk

T = Time period

PAR Study group

Exposed

Not exposed

NCI

Not NCIT

NCI

NCI

Not NCIT

Retrospective

Prospective

Measure

• Percentage– #NCI / # patients

• Incidence density– Patient-days as denominator

• Risk factorsRR= risk in patients exposed

risk in patients not exposed

Positive aspects

• Provide information on several risk factors

• Exposure measures before outcome

• Information on consequences of NCI

• Can identify outbreak

• Ongoing attention

Limitations

• 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……hmer@fhi.no……..….……………….. Region: Oslo………………………… Department Number of

patients at 8 AM

Number of patients operated

Number of urinary tract inf.

Number of pneumonia

Number of surgical site inf.

Number of bacteremia

Number of patients on antibiotic

Total prevalence (%)

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

Total for institution

23 10 8 7 1 39

Use of prevalence surveys

• Show trends

• Estimate – distribution of NCI

– surveillance accuracy

– incidence from prevalence??

– antimicrobial usage patterns

• Rise awareness

Limitations

• Do not identify causes

• Duration of NCI affects the prevalence

• Not very suitable for small institutions

• Difficult to adjust prevalence

Prevalence survey

UTI n=6SSI n=2Incidence surveillance

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

Number of NCI

Incidence (%) 95% confidence interval

50 3 6% (1,3% - 17%) 100 3 3% (0,6% - 8,5%) 100 5 5% (1,6% - 11%) 200 20 10% (6,2% - 15%)

1000 50 5% (3,7% - 6,5%) 3500 100 3% (2,3% - 3,5%) 8000 320 4% (3,6% - 4,5%)

Dummy table

Variable Insidence% 95% confidence interval

Relative risk

95% confidence interval

Relative risk

95% confidence interval

Antibiotic-prophylaxis

Yes 4,6% (300/6500)

(4,1% - 5,2%)

Reference Reference

No 10% (150/1500)

(8,8% - 12%) 2,2 (1,8-2,6) 2,1 (1,7-2,5)

Stratified points 1 5,0%

(350/7000) (4,5% - 5,5%)

Reference Reference

2 7,1% (50/700)

(5,9% - 8,4%)

6,0 (4,8 – 7,5) 6,2 (5,0 – 7,4)

3 16,7% (50/300)

(14%-19%) 10 (8,1 – 12) 9,4 (8,0 – 11)

Etc.

Implementing surveillance system

• Administrators responsibility• Involvement of stakeholders• Identify available resources

– Personnel– Money– Time– Equipment– It- solutions

• Realistic project plan– Organization map– Making forms and letters– It-solutions– Training– Use of data

Making surveillance work

• 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?– 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 Unhappypatients

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Hospital Surveillance HappyPatients

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