Epidemiology and ethics 1

Question 1

Case fatality rate

Answer 1

percentage of people with a given disease who die within a certain amount of time

Question 2

birth rate

Answer 2

live births per 1000

Question 3

fertility rate

Answer 3

live births per 1000

of women aged 15-45 years

Question 4

death rate

Answer 4

deaths/1000

Question 5

neonatal mortality rate

Answer 5

neonatal deaths (first 28 days of life)/10000 live births

Question 6

perinatal mortality rate

Answer 6

neonatal deaths+ stillbirths/1000 total births

Question 7

infant mortality rate

Answer 7

deaths (from 0-1 yo)/1000 live births

Question 8

maternal mortality rate

Answer 8

maternal pregnancy-related deaths (deaths while pregnant or in the first 42 days after delivery)/100,000 live births

Question 9

relative risk

Answer 9

probability of getting disease in group that is exposed to risk factor, compared to (divided by) probability of getting that disease in people who are unexposed

A/(A+B)/C(C+D)

RR>1 positive disease
RR

Question 10

Odds ratio

Answer 10

A/C divided by B/D

Question 11

Attributable risk

Answer 11

difference in risk between exposed and unexposed

A/(A+B)- C/(C+D)

Question 12

Absolute risk reduction

Answer 12

Conceptually similar to calculation of attributable risk, but opposute

C/(C+D)-A/(A+B)

Question 13

NNT

Answer 13

1/ARR
The number of patients you would need to treat in order to save/affect one life

important to determine if a drug should be used or is cost effective

Question 14

Sensitivity

Answer 14

Probability that a screening test will be positive in patients with a disease
A/(A+C)

Question 15

Specificity

Answer 15

D/(B+D)

false positive rate= 1-specificity

Question 16

PPV

Answer 16

PPV= A/(A+B)

what’s the value of the positive test result? likelihood that the person will be positive if they have tested positive

Question 17

NPV

Answer 17

NPV= D/(C+D)

high prevalence gives high positive predictive value

low prevalence gives high negative predictive value

Question 18

Likelihood ratio

Answer 18

does not depend on prevalence

odds of having a positive test result in individuals with a disease, compared with the odds of a positive result in those without the disease

(the positive person should test positive)

PLR= sensitivity/1-specificity
or sensitivity/false pos rate

NLR= 1-sensitivity/specificity
or false neg rate/specificity

Question 19

Negative likelihood ratio

Answer 19

odds of having a negative test result in individuals with a disease compared with the odds of a negative result in those without the disease

NLR= 1-sensitivity/specificity
or false neg rate/specificity

PLR= sensitivity/1-specificity
or sensitivity/false pos rate

Question 20

Accuracy

Answer 20

correct/true results

true pos/true neg/everything

Question 21

Type i error

Answer 21

rejects null even though it’s true

Question 22

Type II error

Answer 22

null hypothesis rejected even though it is false

beta error

Question 23

Statistical significance

Answer 23

statistically detectable difference between 2 groups (not the same as clinical significance)

measured by the arbitraty p value

Question 24

power

Answer 24

ability of study to detect a difference between 2 groups

Question 25

Confidence interval

Answer 25

range of values in which the examiner can be (90,95, 99%) confident that the value obtained from the study truly reflects reality ranges from [mean-z(SEM)] to [mean+z(SEM)] z= 1.645 for 90% 1. 96 for 95% 2. 57 for 99% if CI crosses 1, no relationship if CI for 2 treatment groups crosses 0, there may be no difference between the 2 groups

Question 26

What's important in a screening test? in a confirmatory test?

Answer 26

sensitivity for screening (Catch everybody) | specificity for confirmation (eliminate false pos)

Question 27

what percentage falls within 1,2,3 sd's of the mean in a normal distribution?

Answer 27

68,95,99.7%

Question 28

DMAIC for quality improvement

Answer 28

Define the problem Measure: establish an objective baseline Analyze- identify causes of the problem Improve- identify and implement interventions (re-measure, re-analyze, and re-intervene as needed) Control- maintain the improvement that you achieved

Question 29

Identifies 2 groups: diseased group and healthy group. Retrospectively compares them. Weakened by recall and selection biases

Answer 29

case- control study

Question 30

Seeks to estimate disease prevalence and exposure across a population

Answer 30

cross- sectional study

Question 31

examines a collection of studies on a given subject

Answer 31

meta-analysis

Question 32

prospective blinded study involving placebos, existing therapies, and experimental interventions

Answer 32

RCT

Question 33

Focuses on ONE group with a shared exposure or disease and either prospectively or retrospectively compares them

Answer 33

cohort study

Question 34

examines a collection of cases to seek insight into the disease of interest. Useful in rare diseases

Answer 34

case control

Question 35

Memory errors produce incorrect data

Answer 35

recall bias

Question 36

subject awareness of being studied alerts their answers and behaviors from normal

Answer 36

observational bias

Question 37

certain medical studies attract subjects with particular medical histories rather than general population

Answer 37

selection bias

Question 38

studies that show a difference are preferentially published and then later included in meta- analysis rather than studies that support the null hypothesis

Answer 38

publication bias

Question 39

screening tests designed to detect asymptomatic disease may miss rapidly- progressive disease because the interval between successive screenings only detects slowly- progressive ones

Answer 39

length bias

Question 40

screening test may allow earlier diagnosis of disease but does not translate into actual length of survival

Answer 40

Lead- time bias

Question 41

exemptions from condifentiality

Answer 41

- patient allows physician to share information - disease is legally reportable (HIV, STD, hepatitis, Lyne, door-borne, meningitis, rabies, TB, impaired ability to drive, child abuse, elder abuse) - patient is suicidal or homicidal - penetrating wound from an assault - adolescent with a condition that is harmful to self or others maintain adolescent confidentiality if pertaining to with STDs, pregnancy, or contraception

Question 42

Informed consent

Answer 42

potential risks and benefits of proposed treatment alternative treatments risks of refusing treatment pt can always change their mind not required in an emergency

Question 43

Capacity

Answer 43

patient has the mental ability to make decisions regarding his or her medical care Competence is a legal thing

Question 44

Competence- legalities

Answer 44

not psychotic or intoxicated have understanding of medical situation capable of making decisions

Question 45

medical decisions by parents on behalf of minors may be legally overruled it...

Answer 45

considered harmful to the child in an emergency, treat the patient despite the parents' wishes and get the court order later

Question 46

Durable power of attorney

Answer 46

designates a surrogate decision maker makes decisions consistent with the patient's values "substituted judgment"

Question 47

Living will

Answer 47

written document that details a patient's wishes about specific medical situations out of hospital DNR order advance directive

Question 48

Physician- assisted suicide

Answer 48

physician supplies patient with means of ending his or her life - Oregon - Washington - Vermont - Montana (exceptions) - Canada

Question 49

Euthanasia

Answer 49

physician actively ADMINISTERS lethal agent to patient, to end suffering This is illegal in the US

Question 50

Brain death

Answer 50

- irreversible absence of all brain activity - >6 hrs - absence of cranial nerve reflexes - apnea - absence of brainstem- evoked responses, absence of cerebral circulation, or persistent isoelectric EEG - Cannot be explained by a medical condition that mimics death (encephalopathy, hypothermia, intoxication, locked-in syndrome, Guillain-Barre syndrome)

Question 51

Medical malpractice

Answer 51

Duty of care (legal obligation to conform to a reasonable standard of care) breach of duty (failure to conform to the standard of care) harm causation (breach of duty is the cause of injury or harm)

Question 52

What are the 2 ways that "standard of care" can be established in a malpractice case?

Answer 52

1. expert testimony | 2. Res ipsa loquitur "it speaks for itself" doctrine

Question 53

Vicarious liability principle

Answer 53

supervisors are responsible for the actions of their subordinates

Question 54

When can a physician refuse to treat a patient on the grounds of futility?

Answer 54

1. no rationale for treatment 2. maximal intervention has already failed 3. treatment does not achieve the goals of care