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 Retrospective • Depends on completeness, validity & accuracy of existing data. • Does not identify problems as promptly as concurrent does. • But isn’t expensive. Surveillance methods-2 • Active : •Passive : • accurate • misclassification • complete • underreporting • expensive • lack of timeliness • less expensive Surveillance methods-3 • Hospital wide. • Periodic. • Targeted. • Defining the threshold limit. • Post discharge. Hospital wide surveillance Sources 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 ?