Chapter 4 CIC Surveillance and Epidemiologic investigation

Question 1

1. Identify the median in the following list of numbers: 6,2,9,7,1,4:
   a. 9
   b. 7
   c. 5
   d. 4

Answer 1

1. (C) - 5

The median of a data set is the number that 50 percent of values fall below and 50 percent of the values fall above. The data here not presented in numberical order so first the must be ordered from lowest to highest: 1, 2, 4, 6, 7, 9.

There is an even number of values in this set so to find themedian one must identify the two central numbers and average them. The two central numbers are 4 and 6: 4+6=10 and 10/2 =5

APIC Use of Statistics in Infection Prevention.

Question 2

2. In a study of whether Operating room A (OR A) is associated with a higher number of surgical site infections (SSIs) than Operating room B (OR B), the infection preventionist (IP) is testing whether:

Ho: OR A SSI rate equals OR B SSI rate

H0: OR A SSI rate does not equal OR B SSI rate

2. The IP concludes that the SSI rate in OR A is not equal to the SSI rate in OR B, but in reality the two rates are equal. What type of statictical error has she committed?
   a. No error has been committed.
   b. She committed a Type I error.
   c. She committed a Type II error.
   d. She committed an error equal to ß

Answer 2

2. (B) She committed a Type I error.

If the IP concluded that the SSI rate in OR A is not equal to the SSI rate in OR B, then she rejects the null hypothesis. However, in this case the null hypothesis was true: therefore she has committed a Type I error. This value is equl to “a”.

APIC Use of Statistics in infection prevention

Question 3

3. For which of the following procedure(s) is the surveillance period for deep incisional or organ/space SSI 90 days?
4. ) Cesarean section.
   2) . Craniotomy.
   3) . Coronary artery bypass graft.
   4) . Laminectomy.
   a. 1,2 b. 2,3 c. 3,4 d. 1,4

Answer 3

3. (B) 2,3
   2) . Craniotomy.
   3) . Coronary artery bypass graft.

According to the CDC SSI surveillance definition, postoperative surveillance for deep inscisional or organ/space SSIs should be conducted for 90 days on craniotomy and coronary artery bypass procedures. Superficial incisional SSIs are only followed for a 30 day period for all procedure types.

APIC - Surveillance

Question 4

4. An appropriate indicator to monitor process compliance would be:
   a. Class 1 SSI rate.
   b. Appropriate antibiotic dosage
   c. Central line-associated bloodstream infections (CLABSIs)
   d. Infections caused by multidrug-resistant organisms

Answer 4

4. (B). Apropriate antibiotic dosage

A surveillance program should monitor a variety of outcomes, processes, and events, and some indicators should focus on personnel.

APIC Surveillance

Question 5

5. What key infection control activity is defined as the systematic, ongoing collection, management, analysis, and interpretation of data followed by the dissemination of these data to public health programs to stimulate public health action?
   a. Research
   b. Surveillance
   c. Benchmarking
   d. Accreditation

Answer 5

5. (B) - Surveillance

Surveillance has been defined as the ‘ongoing collection, collation, and analysis of data and the ongoing dessemination of information to those who need to know so that actoin can be taken”

APIC Surveillance

Question 6

6. An IP is reading a journal article that states that the data the authors collected are normally distributed. What does this mean?
   a. When the data are plotted on a curve, it is skewed.
   b. The mean is less than the median.
   c. The skewness value is equal to 1.
   d. The mean, median, and mode of the data are equal.

Answer 6

6. (D) The mean, median, and mode of the data are equal.

If the data are normally distributed, then the mean, median and mode are all equal and the curve will have a bell shape, with most observations clustering at the center and then tapering off on either side of the center.

APIC Use of Statistics in Infection Prevention.

Question 7

7. Which of the following is indicative of a superficial SSI?
   a. Pain at the incision site 10 days after a breast reduction procedure: drainage is culture-positive for methicillin-susceptible Staphylococcus aureus (MSSA).
   b. Stitch abscess that is cultured 14 days after surgery and is positive for Enerococcus faecalis.
   c. Purulent drainage from and episiotomy that occurs withing 5 days of delivery.
   d. Burn wound that cultures positive for Acinetobacter baumannii 10 days after debridement procedure.

Answer 7

7.

(A) Pain at the incision site 10 days after a breast reduction procedure: drainage is culture-positive for methicillin-susceptible Staphylococcus aureus (MSSA).

APIC Surgical Site Infections

Question 8

8. An IP is preparing the quarterly report for the Infection Control Committee. What information will be needed to calculate the CLABSI rate for the ICU?
   1) . The total number of patients in the unit for the time period.
   2) The total number of central line catheters for the time period.
   3) The number of patients who had bloodstream infections identified.
   4) The number of device days for the time period.
   a. 2,3 b. 1,3 c. 1,2 d. 3,4

Answer 8

8.

D 3,4

3) The number of patients who had bloodstream infections identified.
4) The number of device days for the time period.

The numerator would be the number of patients who had bloodstream infections identified and who had a central line during the time period.

Use of Statistics in Infection Prevention

Question 9

9. What type of rate would the IP want to calculate to give feedback to the surgeons at her facility?
   a. Procedure-specific
   b. Provider-specific
   c. Unit-specific
   d. Device-specific

Answer 9

9. b. Provider-specific

APIC performance Measures.

Question 10

10. The IP has been benchmarking her data to other facilities performing similar activities for a period of time. The IP should analyze the entire process to ensure that which of the following conditions are met?
    1) . Standardized definitions are used consistently.
    2) . Overall rates are used to accruately track trends over time.
    3) . Adequate tranining of personnel to collect, store, manage, and analyze data.
    4) . Data are caluclated using the same methodology as a nationally validated system.
    a. 1,2,3 b. 2,3,4 c. 1,3,4 d. 1,2,4

Answer 10

1,2,4

1) Standardized definitions are used consistently
2) Overall rates are used to accurately track trends over time.
4) Data are collected using the same methodology as a nationally validated system.

APIC Surveillance

Question 11

11. The chi-square test can be used:
    1) . To evaluate the effect of a variable on outcomes.
    2) . To analyze continuous data.
    3) . To calculate an odds ratio or relative risk.
    4) . If each cell of the table is greater than 5
    a. 1,2,3 b. 1,2,4 c. 2,3,4 d. 1,3,4

Answer 11

11. d. 1,3,4
    1) . To evaluate the effect of a variable on outcomes.
    3) . To calculate an odds ratio or relative risk.
    4) . If each cell of the table is greater than 5

APIC Statistics in Infection Prevention

Question 12

12. The measure of central tendency most affected by outliers is:
    a. Mean
    b. Median
    c. Mode
    d. Range

Answer 12

12.

a. Mean

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Question 13

13. The p value in statistical test results indicates:
    a. Causation
    b. The probability of having committed a Type I error.
    c. The probability of having committed a Type II error
    d. The probability of data being accurate and valid.

Answer 13

13. b. The probabiltiy of having committed a Type I error.

APIC Use of statistics in Infection Prevention

Question 14

14. On a normaly distributed data set, what percentage of values lies within three standard deviations from the mean?
    a. 68.2
    b. 95.5
    c. 92.4
    d. 99.7

Answer 14

14. d. 99.7

APIC Use of Statistics in Infection Prevention.

Question 15

15. Which statistical test is used when the data are small in numbers?
    a. Fisher’s exact
    b. t test
    c. Chi-square
    d. z test

Answer 15

15. a. Fisher’s exact

APIC Use of Statistics in Infection Prevention

Question 16

16. Statistical process control (SPC) charts are used for all of the following purposes except:
    a. Monitor the process of care.
    b. Facilitate the determination of variation
    c. Eliminate natural variation
    d. Monitor outcomes

Answer 16

16. c. Eliminate natural variation

APIC Porcess Control Charts

Question 17

17. Seventy-five patients were admitted to the Med-Surg ICU. Forty were on the surgical service and 35 were on the medical service. Fifteen patients developed a healthcare-associated infection with methicillin-resistant Staphylococcus aureus (MRSA). Nine of the patients with MRSA infection were on the surgical service. There were 230 patients days in the ICU for the surgical paitents in January, and 325 patients days for medical patients. What was the incidence density of MRSA attack infection for patients on the surgical service?
    a. 29 infections per 1,000 patients days
    b. 26 infections per 1,000 patient days
    c. 19 infections per 100 patient days
    d. 39 infections per 1,000 patients days

Answer 17

17. 39 infections per 1,000 patient days

APIC Statistics

Question 18

18. Plague is endemic in parts of the Southwest United States. The word “endemic” means:
    a. Natives are immune to plague.
    b. An expected number of cases occurs each year in a given geographical area.
    c. Plague has become resistant to all forms of treatment for this population.
    d. The disease is seen in seasonal pattern each year for this area.

Answer 18

18. b. An expected number of cases occurs each year in a given geographical area.

APIC General Principles of Epidemiology

Question 19

19. A pandemic differs from an epidemic in that:
    a. Only one disease is involved
    b. It is usually vectorborne
    c. There is a higher mortality rate.
    d. Several countries or continents are involved.

Answer 19

19. d. Several countries or contenents are involved.

APIC General Principles of Epidemiology

Question 20

20. Specificity of a test for infection or disease is calculated as:
    a. The number of true negatives divided by the number of positives found, times 100.
    b. The number of true negatives divided by the total number of persons with disease, times 100.
    c. The number of true positives divided by the total number of persons with disease, times 100.
    d. The number of true negatives divided by the total number of persons without disease, times 100.

Answer 20

20. d. The number of true negatives divided by the total number of persons without disease, times 100

APIC Use of Statistics in Infection Prevention

Question 21

21. A measure of dispersion that reflects the variability in values around the mean is called the:
    a. Variance
    b. Standard deviation
    c. Range
    d. Bell curve

Answer 21

21. b. Standard deviation

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Question 22

21. In any normal distribution, the proportion of observations that are within two standard diviations of the mean is closest to:
    a. 0.50
    b. 0.68
    c. 0.95
    d. 0.98

Answer 22

21. c. 0.95

APIC Use of Statistics in Infection Prevention.

Question 23

23. The most important feature of nonparametric tests is that they:
    a. Make no assumption about variance in the populations.
    b. Can only be used with ordinal levels of measurements
    c. Require a normal distribution.
    d. Require equal population variances

Answer 23

23. a. Make no assumption about variance in the populations.

APIC Use of Statistics in Infection Prevention

Question 24

24. Which of the following indicates a strong positive correlation?
    a. r = 0
    b. r = -0.993
    c. r = 0.603
    d. r = 0.45

Answer 24

24.

c. r = 0.603

APIC Use of Statistics in Infection Prevention.

Question 25

25. The Employee Health Service has notified the IP that seven employees have P. aeruginosa folliculitis. Inital investigation reveals that six of the seven cases belong to the same health club. Working on the hypothesis that the whirlpool at the health club is associated with the infections, the IP decides to conduct a case-control study using two controls for each case. Which of the following groups is the most appropriate control?
    a. Non-ill family members of the ill emplyees.
    b. Non-ill hospital emplyees mathched for age and sex.
    c. Hospitalized patients with P. aeruginosa folliculitis matched for age and sex.
    d. Non-ill members of the health club matched for age and sex.

Answer 25

25. d. Non-ill members of the health club matched for age and sex.

APIC Research Study Design

Question 26

26. Which of the following steps are not included in hypothesis testing?
    a. State the null and alternative hypotheses.
    b. Set the significance level
    c. Eliminate outliers
    d. Compare the probability value to the significance level

Answer 26

26. c. Eliminate outliers

APIC Use of Statistics inInfection Prevention

Question 27

27. The range of the correlation coefficient is:
    a. -1 to 0
    b. 0 to 1
    c. -1 to 1
    d. None of the above

Answer 27

27. c -1 to 1

APIC Use of statistics in Infection Prevention

Question 28

28. If the index of kurtosis is -1.99, then the curve is:
    a. Relatively flat
    b. Negatively skewed
    c. More peaked
    d. A typical bell-shaped curve or normal distribution

Answer 28

28. a. Relatively flat

APIC use of Statistics in Infection Prevention

Question 29

29. The IP monitors all patients who have coronary artery bypass graft surgery for infections and pneumonia. The probabilty or likelihood of an event occurring is the:
    a. Risk
    b. Attack rate
    c. Host factor
    d. Incidence

Answer 29

29. a. Risk

APIC Use of Statistics in Infection Prevention

Question 30

30. When a study is completed, a report should be written to give the results and evaluation of the study. A good way to display data is by charts or tables. A table is used to illustrate data:
    a. Using one one coordinate.
    b. Arranged in rows and columns
    c. Using a system of coordinates
    d. Showing multiple complex factors at one time

Answer 30

30. b. Arranged in rows and columns

APIC Use of Statistics in Infection Prevention.

Question 31

31. Calculate the mode for the following set of numbers:

2, 11 ,5, 21, 3, 11, 8, 26

a. 24.
b. 10.8
c. 11
d. 9.5

Answer 31

31. c. 11

APIC Use of Statistics in Infection Prevention

Question 32

32. As the sample size increases, how is the power of the study affected?
    a. Power is independent of sample size.
    b. Power is increased.
    c. Power is decreased.
    d. Power approaches 0

Answer 32

32. b. Power is increased.

APIC Use of Statistics in Infection Prevention

Question 33

33. The term for an extraneous variable that systematically carries with the independent variable and influences the dependent variable is a:
    a. Predictor variable
    b. Moderating variable
    c. Experimental variable
    d. Confounding variable

Answer 33

33. d. Confounding variable

APIC Use of Statistics in Infection Prevention

Question 34

34. When a normal distribution is graphed, which of the following are true?
    1) . There is a continous, symmetrical distribution in which both tails extend to inifinty.
    2) . The mean, median, and mode are identical.
    3) . 68.3 percent of the area lies between the mean and +/- 2 standard deviations.
    4) . The shape of the curve is determined by the mean and standard deviation.
    a. 1,2,3 b. 2,3,4 c, 1,3,4 d. 1,2,4

Answer 34

34. d. 1,2,4
    1) . There is a continous, symmetrical distribution in which both tails extend to inifinity.
    2) . The mean, median,and mode are identical.
    4) . The shape of the curve is determined by the means and standard deviation.

APIC Use of the Statistics in Infection Prevention

Question 35

35. Which of the following is not considered one of the criteria for causality:
    a. The incidence of disease is higher in those who are exposed to the factor.
    b. Evidence that the independent and dependent variables are related.
    c. The association has been observed in numerous studies.
    d. The onset of disease must precede exposure to the causal factor.

Answer 35

35. d. The onset of disease must precede exposure to the causal factor.

APIC General Principles of Epidemiology

Question 36

36. Which of the following are true about a frequency polygon:
    1) . Is useful for showing two sets of data on a single graph.
    2) . Uses bars on the x axis.
    3) . Uses connecting lines and data points
    4) . Depicts the percentage of the total that each data point represents.
    a. 1,3 b. 1,4 c, 3,4 d. 2,4

Answer 36

36. a. 1,3
    1) . Is useful for showing two sets of data on a single graph.
    3) . Uses connecting lines and data points

Question 37

37. Targeted surveillance focuses on:
    a. Tracking high-risk, high-volume procedures and potentially preventable healthcare-associated infections (HAIs).
    b. Providing whole-house infection rates.
    c. Tracking infections that are publicly reported.
    d. using the eclectronic surveillance systems to identify infections.

Answer 37

37. a. Tracking high-risk, high-volume procedures and potentially preventable healthcare -associated infections (HAIs)

APIC Surveillance

Question 38

38. The new IP for long-term care facility is assessing adherence to the facility’s hand hygiene policies. Which of the following should he include when reporting his findings?
    a. The number of hand hygiene episodes performed by personnel divided by the volume of soap used in the facility.
    b. The number of hand hygiene episodes performed by personnel divided by the number of patient days times 1,000.
    c. The number of hand hygiene episodes performed by personnel divided by the volume of alchol-based hand rub.
    d. The number of hand hygiene episodes performed by personnel divided by the number of hand hygiene opportunities by ward or service.

Answer 38

38. d. The number of hand hygiene episodes performed by personnel divided by the number of hand hygiene opportunities by ward or service.

Article by Boyce JM. Pittet D. Guideline for hand Hygiene in health-care stettings. morbid mortal rev. 2002 October 25; available on the CDC website.

Question 39

39. Which of the following viruses is the causative agent in Kaposi’s sarcoma?
    a. Herpes zoster virus.
    b. Human herpes virus 8.
    c. Epstein-Barr virus.
    d. Human Papillomavirus (HPV)

Answer 39

39. b. Human herpes virus 8

APIC - Herpes Virus: Kaposi Sarcoma

Question 40

40. The IP receives a call from the ER about a 38 y/o male with a 4-week history of cough and fever. He has just returned from an extended trip to the southwestern United States. Coccidioidomycosis is on the list of possible diagnoses. Which of the following is true regarding the epidemiology of coccidiodoymcosis?
    a. Coccidioides spp. are usually found at high elevations.
    b. Coccidioides spp. are usually found in wet climates.
    c. Up to 50 percent of people in endemic areas have been exposed to Coccidioides spores.
    d. Coccidioides spp. are found on the surface of the soil.

Answer 40

40.

c. Up to 50 percent of people in endemic areas have been exposed to Coccidioides spores.

APIC Fungi:Coccidioidomycosis.

Question 41

41. The IP wish to know the proportion of a disease that could be prevented by eliminating the exposure in the entire study population. In order to determine this information, the IP will need to calculate the:
    a. Attribution fraction
    b. Attribution risk
    c. Population attributable risk percent
    d. Negative predictive value

Answer 41

41. c. Population attributable risk percent

APIC Use of Statistics in Infeciton Prevention

Question 42

42. The precision of an estimate of a relative risk depends on which of the following:
    a. Generalisability
    b. Size of the study
    c. Validity of the study
    d. Presence of bias

Answer 42

42. b. Size of the study

APIC Use of Statistics in Infection Prevention

Question 43

43. The most common reservoir for highly pathogenic avian influenza H5N1 virus is:
    a. Migratory birds
    b. Pigeons and doves
    c. Water fowl
    d. Domestic poultry

Answer 43

43. d. Domestic poultry

APIC Influenza

Question 44

44. Indirect and direct causes of disease may form a complex network of events that determines the level of disease in a community. Which of the following is the term for this interrelation of events?
    a. Applied epidemiology.
    b. Iceberg phenomenon
    c. Causal web
    d. Dendrogram

Answer 44

44.

c. Causal web

APIC Genral Principles of Epidemiology

Question 45

45. Which of the following statements is true when the prevalence of a disease is very low?
    a. The sensitivity of a diagnostic test is greatly increased.
    b. The specificity of a diagnostic test is much greater.
    c. The negative predictive value of a diagnostic test is very low.
    d. The positive predictive value of a diagnostic test is lowered.

Answer 45

45. d. The positive predictive value of a diagnostic test is lowered.

APIC Use of Statistics in Infection Prevention

Question 46

On July 7, a 30 y/o male is admitted to the medical ICU with a 2-day history of acute gastroenteritis symptoms. The IP suspects the patient is infected with norovirus. Which of the following statements regarding the epidemiology of norovirus infection supports this?

a. Most norovirus outbreaks are caused by genotype GII.2.
b. Severe cases of norovirus are most common in adults aged 25 to 45.
c. Noroviruses are the most common cause of epidemic gastroenteritis worldwide.
d. norovirus outbreaks occur most commonly in the summer months.

Answer 46

46. c. Noroviruses are the most common cause of epidemic gastroenteritis worldwide.

APIC Diarrheal Diseases: viral gastroenteritis, Acute Viral.

Question 47

47. What is the attributable risk between the exposed and unexposed population in the following table?

Unexposed Exposed

Disease 9 17

No Disease 7 5

a. 0.21
b. 0.56
c. 0.30
d. 0.77

Answer 47

47. a 0.21

APIC Use of Statistics in Infection Prevention

Question 48

48. A 40 y/o female is admitted with a 3-day history of diarrhea and fever. She is placed in Contact Isolation for a suspected Clostridium difficile infection (CDI). The patient also reports that she has had increasing abdominal pain for the past year, and inflammatory bowel disease (IBD) is in the list of potential diagnoses. Which of the following statements is most accurate regarding the relationship between IBD and CDI?
    a. IBD is associated with increased morbidity and mortality associated with CDI
    b. Most patients with IBD acquire CDI in inpatient settings.
    c. CDI generally develops more slowly after hospital admission among patients with IBD compared with patients without IBD.
    d. IBD does not affect the risk of CDI from antibiotic exposure.

Answer 48

48

a. IBD is assoiciated with increased morbidity and mortality associated with CDI.

APIC Clostridium difficile

Question 49

49. Which of the following statements about TB and airborne diseases among homeless individuals is most accurate?
    a. Most TB infections among homeless individuals are reactivations of established diseases.
    b. Sputum testing detects more than 90 percent of patients with TB.
    c. Screening for TB with chest x-ray may be the most cost-effective approach
    d. Directly observed therapy in the acute hospital setting is associated with the highest completion rates.

Answer 49

49. c. Screening for TB with chest x-ray may be the most cost-effective approach.

APIC Tuberculosis

Question 50

50. In a case-control study, the association between obesity and Clostridium difficile was examined. The table below provides the results. Which of the following odds ratios is correct?

Body mass index BMI Controls Cases

BMI 30 or higher 55 30

BMI less than 25 45 70

a. 0.35
b. 2.85
c. 1.83
d. 0.55

Answer 50

50. b. 2.85

In this scenario, the odds ration is calculated as (55x70) / (30x45) = 2.85.

APIC Use of Statistics in Infection Prevention