Step 2 Dit: Epidemiology (Combined)

Front 1

MC foodborne bacterial infection of the GI tract

Back 1

salmonella

Front 2

Rx for rectal fistula

Back 2

fistulotomy

Front 3

what disease is a/w hampton's hump on x ray

Back 3

Pulmonary Embolism

Front 4

Study design a/w:
identifies diseased group and healthy group and retrospectively compares them

Back 4

case control

Front 5

Study design a/w:
weakened by recall and selection bias

Back 5

case control

Front 6

Study design a/w:
seeks to estimate disease prevalence and exposure across the population

Back 6

cross sectional

Front 7

Study design a/w:
examines a collection of studies on a given subject

Back 7

meta analysis

Front 8

Study design a/w:
prospective blinded study involving placebos, existing therapies and expiramental interventions

Back 8

random clinical trial

Front 9

Study design a/w:
focuses on one group with a shared exposure or disease and either prospectively or retrospectively compares them

Back 9

cohort

Front 10

Study design a/w:
examines a collection of cases and seeks insight into the disease of interest

Back 10

case series

Front 11

Study design a/w:
most useful in a rare disease

Back 11

case series

Front 12

Bias a/w:
memory errors produce incorrect data

Back 12

recall bias

Front 13

Bias a/w:
subject awareness of being studied alters their answers and behaviors from normal

Back 13

observational (or Hawthorne) bias

Front 14

Bias a/w:
certain medical studies attract subject with a particular medical history rather than general population

Back 14

self-selection bias

Front 15

Bias a/w:
studies that show a difference are preferably published and then later included in a meta analysis rather than studies that support the null hypothesis

Back 15

publication bias

Front 16

Bias a/w:
screening tests designed ti detect asymptomatic disease may miss rapidly progressive disease because the interval between successive screenings only detect slowly progressing ones

Back 16

length bias

Front 17

Bias a/w:
screening test may allow earlier diagnosis of the disease but does not translate into actual length of survival

Back 17

lead-time bias

Front 18

Bias a/w:
subjective interpretation of data by the investigator deviates toward "desired" conclusion

Back 18

Investigator/Interviewer (or Pygmalion) bias

Front 19

what does an odds ratio estimate in the case of a disease with a low prevalence

Back 19

relative risk

Front 20

anti HTN used in:
pt's with no comorbidities

Back 20

thiazides

Front 21

anti HTN used in:
pt's with diabetes

Back 21

ACEIs/ARBs

Front 22

anti HTN used in:
pt's with heart failure (multiple answers)

Back 22

ACEIs/ARBs

B-Blockers

Aldosterone antagonist

Front 23

anti HTN used in:
pt's with BPH

Back 23

a-Blockers (e.g. Terazosin)

Front 24

anti HTN used in:
pt's with left ventricular hypertrophy

Back 24

ACEIs/ARBs

Front 25

anti HTN used in:
pt's with hyperthyroid

Back 25

B-Blockers (e.g. Propranolol)

Front 26

anti HTN used in:
pt's with osteoporosis

Back 26

thiazides

Front 27

anti HTN used in:
pt's with benign essential tremor

Back 27

B-Blockers (e.g. Propranolol)

Front 28

anti HTN used in:
pt's with post menopausal female

Back 28

thiazides

Front 29

anti HTN used in:
pt's with migraines

Back 29

B-Blockers
CCB's

Front 30

4 signs and symptoms of streptococcal pharyngitis

Back 30

fever

tonsilar exudate

tender anterior cervical lymphadenopathy

lack of rhinorrhea/cough

Front 31

imaging studies used in a trauma series

Back 31

AP chest/pelvis

AP/lateral C-spine

AP Pelvis

+ FAST ultrasound

Front 32

what is the fundamental difference between all of the "risk" equations and the "odds" equations

Back 32

"RISK" takes an exposure/risk factor and then determines likelihood of developing disease based on that exposure (i.e. cohort study/prospective calculation)

"ODDS" takes a disease state (or lack of disease state) and then determines likelihood that there has been a previous exposure (i.e. case-control/retrospective calculation)

Front 33

equation for risk; what does it tell us

Back 33

R of exposed group = a/(a+b)
R of unexposed group = c/(c+d)

RISK OF GETTING DISEASE:
"risk" is a PERCENTAGE (i.e. part / total); it tells us what percentage people will get disease if exposed (or unexposed)

Front 34

equation for relative risk; what does it tell us

Back 34

RR = risk of exposed/ risk of unexposed
RR = [a/(a+b)] / [c/(c+d)]

"relative risk" is a PROPORTION; it is a "relative" comparison of "risk" b/w 2 groups (e.g. exposed vs unexposed)

Front 35

what does it mean when
RR = 1
RR > 1
RR < 1

Back 35

RR = 1: no relationship (b/w RF & Ds)
RR > 1: positive relationship (b/w RF & Ds)
RR < 1: negative relationship (b/w RF & Ds)

Front 36

equation for attributable risk; what does it tell us

Back 36

AR = risk of exposed - risk of unexposed
AR = [a/(a+b)] - [c/(c+d)]

Front 37

equation for odds; what does it tell us

Back 37

Odds (Ds'd group) = a:c = a/c

Odds (Ds-free group) = b:d = b/c
ODDS OF PREVIOUS EXPOSURE:
"odds" is a RATIO that tells us "LIKELIHOOD" of PREVIOUS EXPOSURE WITHIN a particular group (e.g. ds'd or ds-free)

Front 38

equation for odds ratio; what does it tell us

Back 38

OR = (a/b) / (c/d)
= (a/c) / (b/d)
= ad / bc (simplest to memorize)


"odds ratio" is a ratio of ratios; it tells us "INCREASED LIKELIHOOD" of PREVIOUS EXPOSURE of 1 group (i.e. ds'd) RELATIVE to another group (i.e. ds-free)

Front 39

calculate odds for ds'd & ds-free groups;
calculate odds ratio
EXAMPLE:
10 cancer pt's: 8 previously smoked
10 cancer-free pt's (control grp): 2 previously smoked

Back 39

ODDS:
cancer pt's: 8:2 odds of previous exposure
cancer-free pt's: 1:9 odds of previous exposure

ODDS RATIO:
cancer odds : cancer-free odds
= (8/2)/(1/9) = 36 ==>
cancer pt's are 36x MORE LIKELY to have been smokers THAN cancer-free pt's

Front 40

when is odds ratio a good approximation of relative risk

Back 40

low prevalence (e.g. rare disease)

Front 41

What % corresponds to 1, 2, & 3 standard deviation

Back 41

1 STANDARD DEVIATION: 68%

2 STANDARD DEVIATIONS: 95%

3 STANDARD DEVIATIONS: 99.7%

Front 42

what is most important for screening tests

Back 42

high sensitivity

Front 43

what is most important for confirmatory tests

Back 43

high specificiity

Front 44

What are the equations for Sn & SP

Back 44

Sn = a / (a + c)

Sp = d / (d + b)

Front 45

What are the equations for (1 - Sn) & (1 - Sp)

Back 45

(1 - Sn) = c / (a + c)

(1 - Sp) = b / (d + b)

PROOF: (1 - Sn) = 1 - [a/ (a + c) ]
h/w 1 can be re-written as (a + c) / (a + c)
[(a + c) / (a + c)] - [a / (a + c)]
= (a + c - a) / (a + c)
= c / (a + c)

PROOF: (1 - Sp) = 1 - [d/ (d + b) ]
h/w 1 can be re-written as (d + b) / (d + b)
[(d + b) / (d + b)] - [d / (d + b)]
= (d + b - d) / (d + b)
= b / (d + b)

Front 46

What are the equations for NPV & PPV

Back 46

NPV = d / (d + c)

PPV = a / (a + b)

Front 47

equation for absolute risk reduction; what does it tell us

Back 47

ARR = # of lives saved / # of pt's tx'd

ARR gives us a percentage of lives saved per ONE pt tx'd

Front 48

equation for number needed to tx (NNT); what does it tell us

Back 48

ARR = # of lives saved / # of pt's tx'd

NNT = 1 / ARR

NNT tells us how many pt's must be treated in order to save ONE life; alternatively the formula can be re-written: 1life saved = NNT x ARR

Front 49

What are the equations for the Positive Likelihood Ratio (PLR) & the Negative Likelihood Ratio (NLR)

Back 49

PLR
= Sn / (1 - Sp)
= [a / (a +c)] / [b / (b + d)]

NLR
= (1 - Sn) /Sp
= [c / (a +c)] / [d / (b + d)]

Front 50

types of error:
list all

Back 50

Null hypothesis (H0) = TN's = d

Alternate hypothesis (H1) = TP's = a

Type I (alpha) = FP's = b

Type II (beta) = FN's = c

Front 51

types of error:
accepting the null hypothesis when an association does exist

Back 51

Type II error (beta) --> "free the guilty"

Front 52

types of error:
rejecting the null hypothesis when no association exists

Back 52

Type I error (alpha) --> "convict the innocent"

Front 53

Rx for guilain barre

Back 53

supportive care

plasmaphoresis and IVIG

(NO steroids)

Front 54

what is the cause of chest pain in a young patient that has angina at rest with an ST segment elevation but normal cardiac enzymes

Back 54

prinzmetal's angina

Front 55

what infection can cause diarrhea and pseudoappendicitis

Back 55

Yersinia Enerocolitica

Front 56

what if parents are refusing clearly life saving treatment for their child

Back 56

emergency = do it anyway

non emergency = get court order

Front 57

what circumstance can confidentiality be broken

Back 57

pt permission

suicidal/homicidal

child/elder abuse (obligated)

penetrating assault wounds

reportable diseases

Front 58

4 elements for malpractice claim

Back 58

duty to care
(legal obligation to conform to standard of care)

breach of duty
(failure to conform to standard of care)

harm
(pt was injured/harmed)

causation
(breach of standard of care was cause of injury/harm)

Front 59

what are the two ways to establish standard of care in a malpractive case

Back 59

expert testimony
it speaks for itself ("Res Ipsa Loquitur")

Front 60

Why can a heavily intoxicated pt refusing medical intervention be temporarily tx'd against his/her will

Back 60

An intoxicated pt lacks capacity to make medical decisions, including refusal of care