CIC Surveillance & Epidemiologic Investigation 5 — Questions and Answers
Question 1: Which of the following best defines 'endemic' infection rate in healthcare epidemiology?
- A sudden increase above the expected baseline rate
- The usual or expected background rate of infection in a population (Correct answer)
- An infection rate of zero
- A rate that exceeds national NHSN benchmarks
Correct answer: The usual or expected background rate of infection in a population
The endemic rate is the expected or baseline frequency of infection in a facility, against which increases (outbreaks) are measured.
Question 2: A prospective surveillance system that relies on voluntary reporting by clinicians without active case-finding is best described as:
- Active surveillance
- Passive surveillance (Correct answer)
- Syndromic surveillance
- Sentinel surveillance
Correct answer: Passive surveillance
Passive surveillance depends on clinicians or labs to voluntarily report cases, without the IP actively seeking out infections.
Question 3: Which epidemiologic measure compares disease frequency between an exposed and unexposed group in a cohort study?
- Odds ratio
- Relative risk (risk ratio) (Correct answer)
- Attributable risk percent
- Number needed to treat
Correct answer: Relative risk (risk ratio)
Relative risk (risk ratio) directly compares incidence between exposed and unexposed groups in prospective cohort studies.
Question 4: A hospital IP is performing surveillance for SSIs. Which patient chart element is most critical for determining the date of the index procedure for SSI attribution?
- Anesthesia start time
- Date of the operative procedure (Correct answer)
- Date of first post-op fever
- Discharge date
Correct answer: Date of the operative procedure
The date of the operative procedure is the anchor for NHSN SSI surveillance, determining the 30- or 90-day post-procedure window.
Question 5: An IP discovers that CAUTI rates are much higher in the medical ICU than the surgical ICU. After risk adjustment, the difference disappears. This suggests the initial difference was due to:
- True higher risk in the medical ICU
- Confounding by patient acuity or catheter duration (Correct answer)
- Measurement error in surgical ICU data
- Selection bias in patient assignment
Correct answer: Confounding by patient acuity or catheter duration
When rate differences disappear after risk adjustment, confounding variables (such as patient acuity or duration of catheterization) explain the apparent disparity.
Question 6: Which graph type is MOST useful for identifying the most frequent causes of HAIs to prioritize improvement efforts?
- Line graph
- Pareto chart (Correct answer)
- Box plot
- Scatter diagram
Correct answer: Pareto chart
A Pareto chart ranks causes by frequency and cumulative percentage, helping IPs focus on the 'vital few' factors causing the most HAIs.
Question 7: During a neonatal ICU Klebsiella outbreak, hands of healthcare workers are cultured and one nurse is colonized with the outbreak strain. What should the IP recommend?
- Immediately terminate the nurse's employment
- Furlough the nurse from patient care pending decolonization and clearance cultures (Correct answer)
- Allow continued work with enhanced glove use only
- Re-culture all patients and wait for additional cases
Correct answer: Furlough the nurse from patient care pending decolonization and clearance cultures
A colonized HCW linked to an outbreak should be furloughed from patient care until decolonization is achieved and clearance cultures are negative.
CIC Surveillance & Epidemiologic Investigation 5
Which of the following best defines 'endemic' infection rate in healthcare epidemiology?