CIC Epidemiology Flashcards
Epidemiological triangle
host
/ \
/ \
/ \
/ \
agent -----------environmentResevoir
-place where infectious agent can survive, but might not multiply
Herd Immunity
-high proportion of group resistant to infectious agent
Qualitative research
- understanding human experience
- interpretative approach to subject and context
Fomite
inanimate object where organisms can reside; transmission risk
Quantitative research
-causative relationship suggested by numerical data, at least two variables
Cross-sectional study
- prevalence, correlation or survey study
- population’s risk factors and outcomes reviewed at given point of time
- incidence rates cannot be determined
Case-control study
- population with and without chosen outcome studied for exposure to one or more risk factors
- quick, inexpensive
Clinical Trial
-interventions randomly assigned to participants
usually double blinded (participants and investigator not aware of who is assigned to intervention or control group)
-considered gold standard for casual relationship
-expensive, time consuming
-random assignment results in variable participant characteristics
Attack rate
- (number of new cases with disease or condition/population at risk) x 100
- expressed as a percentage, e.g., 5% of population, or cases per 100 population
Cohort study
-prospective or longitudinal study
population sample with and without exposure to select risk factors studies for outcomes incidence
-stronger casual relationship
Incidence rate
-(number of new cases/population at risk) x constant
constant = multiples of 10 to achieve whole number
Incidence density
-(number of new cases/exposure time, e.g., device days) x constant
Prevalence rate
-(number of existing cases at given moment in time/population at risk at same moment in time) x 100
Sensitivity
-percentage of persons with true POSITIVE results when persons WITH disease tested
specificity
-percentage of persons with true NEGATIVE results when persons WITHOUT disease tested
Nominal scale
- words used to describe groups or categories
- one category is not considered to be higher or lower than another
e. g., nurses, physicians, EVS, etc
Mortality rate
-(number of deaths/population at risk) x 100
Outbreak Investigation
- suspect
- outbreak exists
- collaborate with key persons
a. case definition
b. investigation period
c. case finding methods - formulate hypothesis
- implement and evaluate
- prepare and send reports
Ordinal scale
-numbers used to rank classifications
-relationship between classifications
e.g., likert scale
first, second, third
cancer staging, etc
Range
- difference between largest and smallest number in data set
e. g., data set: 2,3,7,8,21
range: 21-2=19
“Out of Control” data
- data point above UCL or below LCL
- nine consecutive points on one side of mean
- six consecutive points increasing or decreasing
- 14 consecutive points alternating up and down
- 15 consecutive points 1 SD above or below mean
- 2 of 3 consecutive points within 2 to 3 SD
- 4 of 5 consecutive points within 1 to 2 SD
Interval scale
-original data with difference between any two observations
e.g., 1-3, 4-6, 7-9
age, BP, weight, temperature, etc.
Deviation
-actual difference between data point and mean
Prospective study
- usually require long follow up period
- looks forward
Chi square test
- evaluated effect of variable on outcomes
- calculates odds ratio or relative risk
- data in each cell needs to be greater than 5
Surveillance
- includes data collection, data analysis & correlation
- does not include causation
Mean
Mode
Median
- average
- most frequent number in data set
- middle
Epidemiology
- study of distribution & determinants of disease
- studies frequency, types and factors that influence illness and injury in groups
- body of knowledge
- method of study
Fisher’s Exact test
-used when numbers are small
Normal distribution (graphed)
- continuous, symmetrical distribution, both tails extend to infinity
- shape of curve determined by mean and SD
- 95.5% data lies between mean & +/- 2 SD
Casual association
- one factor increases probability of occurrence
- determined by strength of identification, consistency & biological plausibility
Positive predictive value
-percentage of POSITIVE tests when disease PRESENT
Epidemic curve
- Helps determine if source of infection common, and/or continuing
- identify probable exposure to source
- identify probable incubation period
- determine if problem is ongoing
Standard deviation
-measure of dispersion that reflects data variability around mean
Negative predictive value
-percentage of NEGATIVE tests when DISEASE IS NOT PRESENT
