3 - Epidemiology Flashcards
3 purposes of epidemiology
1) Determine amount/distribution of disease
2) Investigate causes
3) Apply knowledge to control of disease
Prevalence measures the ____ of disease
Amount
Incidence measures the _____ of new disease
Occurrence
“Extent” definition
Number or proportion of teeth or sites that are affected with a given condition
“Severity” definition
How advanced or serious a given condition is
Cross sectional studies determines _____ and is good for studying disease that _____
Prevalence
Affect a large population
Case control studies is good for studying diseases that ______
Are rare
Cohort studies determines ____
Incidence
3 types of experimental study designs
Randomized parallel arm
Crossover
Split-mouth
Sensitivity definition
____ ____ rate
Equation?
Disease is present, how often the test is positive
True positive rate
A/(A+C)
Specificity definition
___ ____ rate
Equation
Disease is absent, how often the test is negative
True negative rate
D/(B+D)
PPV definition
Equation
Test is positive, how often is the disease truly present
A/(A+B)
NPV definition
Equation
Test is negative, how often the disease is truly absent
D/(C+D)
What is the problem with highly sensitive test?
False positives
What is the problem with highly specific tests?
False negative
Association between PPV + disease prevalence
PPV decreases as prevalence decreases
“Risk” definition
The likelihood of a person getting a disease in a specified time period
“Risk factor” definition
The characteristic of an individual that places them at increased risk of getting a disease
Periodontal disease risk factors
Age
Smoking
Diabetes
Certain subG bacteria
“Risk assessment” definition
The process of predicting an individual’s probability of disease
“Odds ratio” definition
Odds of being exposed to a given factor among subjects with the disease divided by the odds of being exposed among healthy subjects
Odds ratio used in ___ and ____ studies
Cross-sectional
Case control
OR >1 indicates ____?
Subjects more likely to have been exposed to a given factor than healthy subjects
“Risk ratio” definition
Risk for development of the disease among the exposed divided by the risk for development of disease among the non-exposed subjects
Risk ratio used in ____ studies
Cohort/longitudinal
RR >1 indicates _____?
Exposed subjects at greater risk for disease development
RR <1 indicates ____?
Exposure is protective of disease development
“Prognosis” definition
Predicting the course or outcome of a disease
“Gingivitis” definition
Inflammation of the gingiva with no loss of periodontal attachment
Prevalence of gingivitis in US? What study?
NHANES III
50%
What groups are more susceptible to gingivitis?
Puberty, pregnancy, birth control pills, males
What study showed that the “cause” of gingivitis is bacterial plaque?
Loe 1965 - Experimental gingivitis
Prevalence of periodontitis in US? What study?
NHANES III
35% of adults 30+
22% mild
13% moderate-severe
Prevalence of gingival recession in the US? 2 different age ranges
> 1mm GR in 38% of 30-39 year olds
90% of 80-90 years old
4 ways of measuring periodontitis
1) Russll PI - no probe, underestimates prevalence
2) Ramfjord PDI - 3,9,12,19,25,28
3) BOP
4) Radiographic
Prevalence of AgP?
LAP 0.53%
GAP 0.13%
% of incidental attachment loss
1.61%
