BIOL 437 Ch. 12 (Clinical Epidemiology)

Question 1

clinical epidemiology

Answer 1

-focuses on patients and application of epidemiolgoic methods to assess efficacy of screening, diagnosis and treatment

Question 2

clinical epidemiology is used to

Answer 2

-identify health consequences of employing a test or administering treatment

Question 3

secondary prevention

Answer 3

-health screening and detection activities used to identify disease

Question 4

examples of screening methods

Answer 4

• pap test
• mamograms
• blood tests
• biopsy
• small blood sample

Question 5

medical screening

Answer 5

-used to suggest or detect disease among individuals in a population without signs or symptoms of the health problem

Question 6

why do we do screening?

Answer 6

-promote the detection of disease in their earliest stages, when treatment has the greatest chance of working
>to reduce morbidity and mortality

Question 7

mass screening

Answer 7

• not selective

- involves application of screening tests to the total population

Question 8

selective screening

Answer 8

-applying the screening tests to high risk groups

Question 9

screening guidelines (WHO 1968)

Answer 9

• major medical problem
• acceptable treatment
• access to health care services
• recognizable course
• suitable and effective test
• testing process acceptable to general population
• natural history known
• procedures for those who need further testing
• simple process

Question 10

evaluating screening guidelines using descriptive and analytical epidemiology

Answer 10

• extent of public health problem
• efficacy of treatment
• access to health care
• natural course of disease
• efficacy of screening or diagnostic test

Question 11

validity

Answer 11

-how well the test actually measures what it is supposed to measure

Question 12

reliability

Answer 12

• how well the test performs in use over time

* repeatability

Question 13

yield

Answer 13

-amount of screening the test can accomplish in a period of time

Question 14

validity refers to

Answer 14

-accuracy and trustworthiness of instruments, data and findings in research

Question 15

2 ways to view and assess validity

Answer 15

1. Content validity

2. Construct validity

Question 16

content validity

Answer 16

-achieved when instrument has appropriate content for measuring a complex concept or construct

Question 17

construct validity

Answer 17

-the measues ‘get at’ or actually measure what you are actually studying

Question 18

accuracy

Answer 18

• degree to which measurement represents what it is intended to represent
• important influence on validity

Question 19

sensitivity

Answer 19

• ability of a test to correctly identify those WITH the disease
• proportion of subjects with the diease who have a positive test

Question 20

sensitivity equation

Answer 20

=TP/ (TP+FN)

Question 21

specificity

Answer 21

• ability of a test to correctly identify those WITHOUT the disease
• proportion of subjects without the disease who have a negative test

Question 22

specificy equation

Answer 22

=TN/ (TN+FP)

Question 23

overall accuracy

Answer 23

-ability of a test to predict the presence or absence of a disease

Question 24

PV+

Answer 24

-proportion of people with a positive test result who have the disease (relates to sensitivity)

Question 25

PV-

Answer 25

-proportion of people with a negative test result who do not have the disease (relates to specificity)

Question 26

likelihood ratios

Answer 26

-2 additional measures of appraising screening and diagnostic evidence >LR+ >LR= -less sensitive to variations in base rate than specificity and sensitivity

Question 27

base rate

Answer 27

-percentage of people in a sample with the health-related state or event of interest

Question 28

LR+

Answer 28

=sensitivity/(1-specificity) | -level of convidence that a person who obtains a score in the affected range truly DOES have the health problem

Question 29

LR-

Answer 29

=(1-specificity)/sensitivity | -confidence that a score in the unaffected range comes from a person who truly DOES NOT have a health problem

Question 30

prognosis

Answer 30

-prediction of the course of the disease based on anticipation from the natural hisotry of the disease

Question 31

prognostic indicators

Answer 31

-tell the doctor the likely behaviour of the cancer and its responsiveness to treatment

Question 32

measures of prognosis

Answer 32

- case fatality rate | - survival rate

Question 33

case fatality rate

Answer 33

-proportion of newly diagnosed cases that die from a given disease in a specified period

Question 34

survival rate

Answer 34

-proportion of persons surviving, regardless of cause of death

Question 35

Cox proportional hazards regression model

Answer 35

-useful for analyzing survival data -indicates probability that a person will experience an event -estimate relative risk, adjusted for potential prognositc factors >minimizes threat of confounding

Question 36

lead time

Answer 36

-difference in time between the date of diagnosis with screening and date of diagnosis without screening

Question 37

lead time bias

Answer 37

- when lead time is counted in the survival time of patients | - gives a misleading picture of the benefit of treatment

Question 38

selection bias

Answer 38

- choosing data that distorts the outcome of a test | - may make a test look better or worse than it really is, in terms of survival

Question 39

over-diagnosis bias

Answer 39

- when screening identifies an illness that would not have shown clinical signs before a person's death from other causes - makes screening efforts look good because of increased identifications of abnormalities - individual may undergo unnecessary treatment with its accompanying risk

Question 40

avoiding bias

Answer 40

- randomized controlled trial= GOLD standard | - different prognositc factors are balanced between groups and "true" screening or treatment effect can be determined

Question 41

outcome research

Answer 41

- a relatively new field that seeks to understand the end results of clinical practices and interventions - combines info about the care people are getting - important in developing better ways to monitor and improve clinical care

Question 42

clinical epidemiology conclusion

Answer 42

- involves application of epidemiologic methods to improve quality and value of patient care - involves assessment of the efficacy of screening, diagnosis and treatment strategies in clinical settings