nosocomial infection surveillance methods masud yunesian, m.d., epidemiologist
TRANSCRIPT
NOSOCOMIAL INFECTION
SURVEILLANCE METHODS
Masud Yunesian,M.D., Epidemiologist
Definition
• A dynamic process of gathering, managing,
analyzing and reporting data on events that occur in a specific population
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.
Steps in surveillance:
• Definition of the event(s).• Systematic collection of data.• Summarization of data.• Analysis & interpretation.• Consuming the results for
improvement.
Purposes of the surveillance-1
1. Reducing the infection rate within a hospital.
2. Establishing endemic (baseline) rates.
3. Identifying outbreaks.
Purposes of the surveillance-2
4. Convincing medical staff.5. Satisfying regulators.6. Defending malpractice claims.7. Comparing infection rates
among hospitals.
Surveillance methods-1
1.Concurrent
2.Retrospective
Concurrent
• Flexible,• Informative • Timely • Capable of cluster detection• Capable of changing behavior• But expensive
• Depends on completeness, validity & accuracy of existing data.
• Does not identify problems as promptly as concurrent does.
• But isn’t expensive.
Retrospective
Surveillance methods-2
•Active :• accurate
• complete
• expensive
•Passive :• misclassification
• underreporting
• lack of timeliness
• less expensive
Surveillance methods-3• Hospital wide.• Periodic.• Targeted.• Defining the threshold limit.• Post discharge.
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.
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
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)
Characteristics of targeted S.
• High accuracy & efficiency .• Incapable of detecting other
infections .• Criteria for selection of target :
– Frequency.– mortality & morbidity .– Cost.– preventability.
Defining the threshold limits
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, .. )
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.
Analysis-2
Numerator & Denominator
Overall rate =
No. of NI
Total no. of admitted or discharged patients
Adjusted rates
• For severity of illness.
• For length of stay.
• For exposure to device (e.g. ventilator)
Essential numerator data:
• Demographic :– name, age, sex , service, ward,admission
date, hospital identification number .
• Infection :– onset date , site of infection.
• Laboratory :– pathogen antibiogram
Numerator data : Risk factors“only 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.
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.
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,– ...
“Dissemination” “Surveillance is not complete
until the results are disseminated to those who use
it to prevent and control”
dissemination - continued
• Confidentiality must be regarded • Regular time intervals for
reporting .• Format of reports :
–Summary , table , graph
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 ?