Biostat

Question 1

what is sensitivity?

Answer 1

probability that person with disease has a positive test. if negative rule out disease

Question 2

what is specificity?

Answer 2

probability that person without disease has a negative test. if positive, rule in disease

Question 3

RR?

Answer 3

a/a+b/c/c+d

Question 4

OR?

Answer 4

ad/bc

Question 5

what is precision testing and what reduces precision?

Answer 5

reliability. random variation reduces precision.

Question 6

what is accuracy testing and what reduces accuracy?

Answer 6

validity. systematic error (bias) decreases accuracy

Question 7

increase in precision affects what 2 values?

Answer 7

increase power, decrease std deviation

Question 8

odd ratio calculated in what observational study?

Answer 8

case control (looks at endpoint (disease) and than tries to determine risk factors)

Question 9

relative risk calculated in what observation study?

Answer 9

cohort (has a risk factor and looks back to see who developed disease with risk factor)

Question 10

when does OR=RR?

Answer 10

when outcome is uncommon in a population

Question 11

what helps control confounding variables?

Answer 11

matching such that both groups have similar distribution (eg age, race) in accordance with those variables

Question 12

biases pose a threat to what of the study?

Answer 12

validity

Question 13

methods to decrease confounding bias?

Answer 13

matching, restriction, randomization

Question 14

attributable risk?

Answer 14

a/a+b-c/c+d

Question 15

relative risk and incidence can only be calculated from what?

Answer 15

prospective or experimental trials (ex prospective cohort)

Question 16

what values significant for OR and RR?

Answer 16

any value besides 1

Question 17

odds ration can be calculated for what?

Answer 17

retrospective (ex case control)

Question 18

another name for prevelance surgery?

Answer 18

cross-sectional

Question 19

what is an epidemic?

Answer 19

observed incidence greatly exceeds expected incidence

Question 20

define and give an example for nominal, ordinal, and continuous types of data and type of test it is associated with?

Answer 20

nominal-no numeric value (eg day of week)
ordinal-ranking but no quantification (eg class rank does not specify how far number 1 is ahead of you)
continuous-numerical measurement
chi squared (nominal or ordinal), t-test or anova (continuous)

Question 21

define p-value?

Answer 21

that the data were obtained by random error or chance

Question 22

what correlates to chance of making type 1 error?

Answer 22

p-value because it claims that an effect or difference is presence when none really exists. so if p is 4%, there is less than 4% chance making type I error

Question 23

what is type II error?

Answer 23

saying there is no difference (null hypothesis accepted) when one actually exists

Question 24

what is power and how do you increase?

Answer 24

probability of rejecting null hypothesis when it is actually false. increase sample size

Question 25

how do you know if you have a confounding variable?

Answer 25

it affects both the independent (manipulated) and dependent (outcome) variables

Question 26

what is admission rate bias?

Answer 26

hospital A and B compared for mortality for MI. A is greater than B, but acutally they have tougher admission criteria and take sicker so they will have greater mortality

Question 27

what is unacceptability bias?

Answer 27

ppl do not admit to embarassing behavior, claim to exercise more or claim to take experimental drugs and spit them out

Question 28

test needed for caustic ingestion?

Answer 28

generally alkaline. need upper GI endoscopy within 24 hours to access extent of injury

Question 29

cyanide poisoning management options for dermal, ingested, and all exposure?

Answer 29

dermal-remove clothing, skin decontamination ingestion-activated charcoal all: 1) hydroxocobalamin 2) sodium thosulfate 3) nitrites followed by thiosulfate if not first two

Question 30

best initial step vs best tx for organophosphate?

Answer 30

best initial step-remove all clothes and washing of skin to prevent more pesticide absorption best tx-atropine

Question 31

tx diphenydramine poisoning?

Answer 31

anticholingergic/antihistaminic properties (Dry as a bone, red as a beet, blind as a bat, hot as a hare, full as a flask, mad as a hatter, Physostigmine

Question 32

tx iron poisoning

Answer 32

whole bowel irrigation, deforoxamine

Question 33

best predictor intox for opioid?

Answer 33

decreased RR

Question 34

differentiate opioid vs benzo intox?

Answer 34

degree of resp depression and miosis in opioid (vs normal pupils in benzo)

Question 35

when do you give activated charcoal for acetaminophen?

Answer 35

greater than 7.5 g or greater than 150 mg/kg for kid in less than 4 hours ingested

Question 36

nahco3- antidote for what and what does it help do?

Answer 36

TCA poisoning and alleviates cardiac toxicity of QRS widening and possible ventricular arrhythmia as Na+ competes for TCA spots increasing gradient across cardiac cells

Question 37

exertional vs nonexertional heat stroke?

Answer 37

exertional-problem with heat dissipation due to thermoregulation failure nonexertional-underlying impaired thermoregulation due to meds and underlying illness

Question 38

central scotoma, decreased afferent pupillary reflex, visual blurring, and altered mentation

Answer 38

methonal ingestion

Question 39

flank pain, hematuria, oliguria, CN palsy, and tetany

Answer 39

ethylene glycol

Question 40

cns depression, disconjugate gaze, and absent ciliary reflex intox?

Answer 40

isopropyl alcohol ingestion

Question 41

tx otitis externa

Answer 41

topical ofloxacin, neomycin, polymyxin B

Question 42

cause and tx infections myringitis?

Answer 42

Mycoplasma or S pneumoniae. macrolides

Question 43

Describe rinne and weber?

Answer 43

Weber-conductive test where put in center of head. in conductive hearing loss, sound localized to affected ear. in sensorineural hearing loss, sound localized to unaffected ear. Rinne-compares air with bone and placed on mastoid until no longer than removed to auditory meatus. in conductive hearing loss (bone greater than air) so cannot hear near meatus. in sensorineural, both air and bone conduction decrease so they can hear both