NOSOCOMIAL%20INFECTION

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NOSOCOMIAL INFECTION

• SURVEILLANCE METHODS

Masud Yunesian, M.D., Epidemiologist
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Definition

• A dynamic process of gathering, managing,
  analyzing and reporting data on events that occur
  in a specific population

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Importance SENIC study

• Surveillance was the only component essential for
  reducing SSI, Pneumonia, UTI, bacteremia.
• Other essential components
• Sufficient no. of trained infection control
  staff and A system for reporting infection rates
  of SSI to surgeons.

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Steps in surveillance

• Definition of the event(s).
• Systematic collection of data.
• Summarization of data.
• Analysis interpretation.
• Consuming the results for improvement.

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Purposes of the surveillance-1

1. Reducing the infection rate within a hospital.
2. Establishing endemic (baseline) rates.
3. Identifying outbreaks.

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Purposes of the surveillance-2

• 4. Convincing medical staff.
• 5. Satisfying regulators.
• 6. Defending malpractice claims.
• 7. Comparing infection rates among
  hospitals.

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Surveillance methods-1

1. Concurrent
2. Retrospective

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Concurrent

• Flexible,
• Informative
• Timely
• Capable of cluster detection
• Capable of changing behavior
• But expensive

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Retrospective

• Depends on completeness, validity accuracy of
  existing data.
• Does not identify problems as promptly as
  concurrent does.
• But isnt expensive.

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Surveillance methods-2

• Active
• accurate
• complete
• expensive

• Passive
• misclassification
• underreporting
• lack of timeliness
• less expensive

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Surveillance methods-3

• Hospital wide.
• Periodic.
• Targeted.
• Defining the threshold limit.
• Post discharge.

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Hospital wide surveillanceSources of data

1. Daily reports of microbiology labs.
2. Medical records of febrile patients.
3. Medical records of patients taking antibiotics.
4. Medical records of isolated patients
5. Daily interview with nurses patients
6. Periodic review of autopsy reports
7. Periodic review of medical records of staff.

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Periodic surveillance(S.)

• Hospital wide (H.W.S) during specified periods,
• And ,
• Targeted S. during alternate periods
• Or ,
• Rotating H.W.S. from one unit to another

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Targeted surveillance

• Focuses its effort on
• Selected geographic area (e.g. ICU)
• Selected service (e.g. cardio thoracic surgery)
• Specific populations of patients or infections
• At high risk of acquiring infection ( e.g.
  transplantation)
• Undergoing specific interventions( e.g. dialysis)
• At specific site (e.g. blood stream)

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Characteristics of targeted S.

• High accuracy efficiency .
• Incapable of detecting other infections .
• Criteria for selection of target
• Frequency.
• mortality morbidity .
• Cost.
• preventability.

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Defining the threshold limits
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Case finding issues

• Total chart review (standard method).
• Laboratory reports.
• Clinical ward rounds (twice a week).
• Kardex screening (once or twice a week).
• Fever chart.
• High risk patients (transplant, diabetic,
  leukemia, invasive methods, .. )

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Analysis-1

• The data should be analyzed.
• The analysis should be done by staff engaged in
  surveillance.
• Staff should decide how frequently to
  analyze the data
• Frequently enough to detect clusters promptly.
• Collecting the data for a long enough period of
  time for changes to be meaningful.

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Analysis-2

• Numerator Denominator

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Overall rate No. of NI
Total no. of admitted or discharged patients
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Adjusted rates

• For severity of illness.
• For length of stay.
• For exposure to device (e.g. ventilator)

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Essential numerator data

• Demographic
• name, age, sex , service, ward,admission date,
  hospital identification number .
• Infection
• onset date , site of infection.
• Laboratory
• pathogen antibiogram

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Numerator data Risk factorsonly when these
data used for analysis

• An example for SSI
• Kind of surgery.
• Date of surgery.
• Duration of surgery.
• Type of wound (clean ,dirty, ).
• Date of discharge.

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Denominator data

• Total no. of admitted or discharged pts.
• OR
• No. of days of exposure
• Total no. of pts. pt-days in the unit,
• Total no. of ventilator days,
• Total no. of central line days,
• Total no. of urinary catheter days.

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Comparing rates necessary assumptions

• Same definitions.
• Same methods of S. case finding.
• Same accuracy of methods personnel.
• Same characteristics of hospitals/wards
• Length of stay,
• Risk indices,
• exposure to devices,
• ...

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Dissemination Surveillance is not complete
until the results are disseminated to those
who use it to prevent and control
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dissemination - continued

• Confidentiality must be regarded
• Regular time intervals for reporting .
• Format of reports
• Summary , table , graph

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Evaluation

• At least annually ask yourself
• Did the system detect clusters ?
• Which practices were changed based on S. ?
• Were the data used to decrease the endemic
  rate ?
• Were the data used to assess the efficacy of
  interventions ?
• Are administrative clinical staff aware of
  Surveillance Findings ?