O BJECTIVES (38 Q UESTIONS ) Design of Surveillance Systems Collection and Compilation of Surveillance Data Interpretation of Surveillance Data Outbreak Investigation Healthcare Associated Infections

D ESIGN OF S URVEILLANCE S YSTEMS

Definition: The purpose is to understand the causes of disease by knowing distribution, natural history and determinants in terms of person, place and time E PIDEMIOLOGY

Relationship between host, environment, and agent E PIDEMIOLOGICAL T RIANGLE

A causal association is one that evidence indicates one factor is clearly implicated. An Indirect association is a mixing effect and may be a confounding variable. Statistics do not prove causality only suggest and association A SSOCIATION AND C AUSATION

Incidence number of new cases of disease in a given time period Prevalence number of cases occurring in a population I NCIDENCE AND P REVALENCE

E PIDEMIOLOGICAL STUDY DESIGN Observational (descriptive and analytic) Experimental (clinical community trials) Used for theory verification Persons are studied as a whole, not independent of their environment QuantitativeQualitative

C OLLECTION AND C OMPILATION OF S URVEILLANCE D ATA

D ESCRIPTIVE S TATISTICS Rate: frequency of an event in a defined population per unit of time Prevalence rate : numerator is the number of existing cases of disease in a population; denominator is the population at risk Incidence rate : numerator is the number of new cases in a defined population; denominator is the defined time period for the population at risk Incidence density : new cases/exposure time

M EASURES OF ASSOCIATION, 2 X 2 TABLE DiseaseNo diseaseTotal Factor presentaba+b Factor absentcdc+d a+cb+dN

R ELATIVE VS. ODDS RATIO Relative ratio (risk ratio) a ÷ c a + b c + d probability of developing disease if risk factor is present probability of developing disease if risk factor is not present Odds ratio (a x d) ÷ (c x b) probability of having a risk factor if disease is present probability of having a risk factor if disease is not present

S ENSITIVITY VS. S PECIFICITY Sensitivity a ÷ (a + c) x 100 true positive test Specificity d ÷ (b + d) x 100 true negative test

Positive predictive value a ÷ (a + b) x 100 % tests positive when disease present Negative predictive value d ÷ (c + d) x 100 % tests negative when disease not present P OSITIVE VS. NEGATIVE PREDICTIVE VALUE

S TATISTICAL TERMS TO KNOW Mean average of the set of values Median point in a series that divides that numbers in half (middle) Mode value in the data that occurs most frequently Range difference from lowest to highest

S TATISTICAL TERMS TO KNOW Standard deviation variability around the mean Variance square of standard deviation (similar to SD) Frequency distribution normal ( 68.2% is 1 SD, 95.5% is 2 SD, 99.7% is 3 SD)

I NTERPRETATION OF S URVEILLANCE D ATA

H YPOTHESIS Hypothesis testing estimates the likelihood that the result did not occur by chance Null Hypothesis (Ho) it is stated to be rejected; hypothesis testing will either accept or reject the null hypothesis

I NFERENTIAL STATISTICS P value a probability that your test is true; this is based on the level of significance assigned by the investigator ( <.05) Confidence interval the range of values that is likely to be included data set

D ATA P RESENTATION Tables: show frequency Graphs : epidemiologic information should be displayed in a histogram because it depicts disease over time Bar charts: use for only one coordinate Pie charts: to show the percentage of the whole

C ONTROL C HARTS Interpretation (out of control) 1. One data point above UCL or below UCL 2. 2 of 3 consecutive points are -2SD but -3 SD on one side of the mean 3. 4 of 5 consecutive points are –SD but -2 SD on one side of the mean 4. 9 consecutive points on one side of mean 5. 6 consecutive points increasing or decreasing consecutive points alternating up or down consecutive points within 1 SD above or below the mean

O UTBREAK I NVESTIGATION

o Outbreak o an increase over the expected occurrence of an event; o exception – one case of an unusual disease (e.g., botulism) may constitute an epidemic. o “pseudo-outbreak” is generally applied to situations in which there is a rise in test results (e.g., positive microbiology cultures) without actual clinical disease.

INITIAL O UTBREAK I NVESTIGATION o Confirm presence of an outbreak o Alert key partners about the investigation o Perform a literature review o Establish an initial case definition o Develop a methodology for case finding o Prepare an initial line list and epidemic curve o Observe and review potentially implicated patient care activities o Consider whether environmental sampling should be performed o Implement initial control measures

o Refine the case definition o Continue case finding and surveillance o Regularly review control measures o Considering whether an analytical study should be performed o Prepare and disseminate reports FOLLOW UP INVESTIGATION

Graph in which the cases of a disease that occurred during an epidemic (outbreak) are plotted according to the time of onset of illness in the cases. The shape of the curve is determined by the epidemic pattern. The epidemic curve is used to: o Determine whether the source of the infection was common, propogated (continuing),or both o Identify the probable time of exposure of the cases to the source(s) of infection o Identify the probable incubation period o Determine if the problem is ongoing T HE E PIDEMIC C URVE

H EALTHCARE A SSOCIATED I NFECTIONS

CDC DEFINITION OF HAI An infection meeting the following criteria: a. Not present or incubating on admission b. Develops during the course of receiving treatment for other conditions c. Incubating at the time of admission that is related to previous hospitalization at the same facility or identified in an admission following performance of a procedure during a previous admission d. Healthcare workers acquire while performing their duties within a healthcare setting e. HAIs include those that occur in the course of care in acute care hospitals, long-term care, behavioral health, correction facilities, dental care, home health, outpatient medical and surgical clinics, dialysis centers, radiology centers, etc.

C OMMUNITY - ASSOCIATED VS. IATROGENIC Community-associated infections present or incubating on admission to the healthcare facility and not associated with previous treatment/procedures at that healthcare facility Iatrogenic infection infection arising from the actions or treatments of a physician or healthcare provider or a secondary condition arising from treatment of a primary condition

U RINARY T RACT I NFECTION SUTI – Symptomatic Urinary Tract Infection ABUTI – Asymptomatic Bacteremic UTI OUTI – Other Infections of the Urinary Tract (Kidney, Ureter, Bladder, Urethra or Tissues Surrounding the Retroperineal or Perinephric Spaces)

S URGICAL S ITE I NFECTION Superficial (Primary/Secondary) – Superficial Incisional Surgical Site Infection Deep (Primary/Secondary) – Deep Incisional Infection Organ/Space – SSI (organ/space)

O RGAN /S PACE – SSI ( ORGAN / SPACE ) Osteomyelitis Breast abscess or mastitis Myocarditis or pericarditis Disc space Ear, mastoid Emdometritis Endocarditis Eye, other than conjunctivitis Gastrointestinal (GI) tract Intra-abdominal, no specified elsewhere Intracranial, brain abscess or dura Joint or bursa Other infections of the lower respiratory tract Mediastinitis Meningitis or ventriculitis Oral Cavity Other male or female reproductive Other infections of the urinary tract Spinal abscess without meningitis Sinusitis Upper respiratory tract, pharyngitis Arterial or venous infection Vaginal cuff

P NEUMONIA Criteria for defining nosocomial pneumonia – general comments applicable to all pneumonia specific site criteria VAP: Ventilator-associated pneumonia (i.e., pneumonia in persons who had a device to assist or control respiration continuously through a tracheostomy or by endotracheal intubation within the 48-hour period before the onset of infection, inclusive of the weaning period) should be so designated when reporting date. VAE: Ventilator-associated event new definition

BSI - B LOOD S TREAM I NFECTION LCBI (Adult & Children) – Bloodstream Infection, Laboratory – Confirmed CLABSI – LCBI occurring when a central line is in place, and no other source of infection noted (must meet criteria for other site)

O THER HAI S BJ -Bone and Joint Infection (Bone & Joint) CNS -Central Nervous System Infection (Disc & Intracranial & Meningitis & Spinal Abscess) CVS -Cardiovascular System Infection (VASC & ENDO & CARD & MED) EENT -Eye, Ear, Nose, Throat or Mouth(Conj, Eye, Ear, Oral, Sinu, UR) GI -Gastrointestinal System (GE, GIT, HEP) IAB -Intra-abdominal (NEC) LRI -Lower Respiratory Tract Infectin (Bron, Lung) REPR -Reproduction Tract (EMET, EPIS, VCUF, OREP) SST -Skin and Soft Tissue (Skin, DECU, Burn, BRST, UMB, PUST, CIRC) SYS -Systemic Infection ( DI)