Biostats

Question 1

observational studies

Answer 1

cross-sectional - frequency of disease and risk factors, shows association (not causality)

case-control - OR (pts with COPD had higher odds of a history of smoking than those without COPD)
odds ratio = [disease/no disease in exposure group]/ [disease/no exposure with no exposure]

cohort - RR
relative risk = %disease with risk factor/% disease without risk factor

Question 2

clinical trial

Answer 2

does the drug SWIM

1) healthy volunteers - safe?, assess drug properties
2) small no of pts with disease - work?
3) RCT - improvement?
4) postmarketing surveillance of pts after treatment is approved - stay on the market?

Question 3

PPV and NPV

Answer 3

depend on disease prevalence

PPV = true pos/all pos
NPV = true neg/all neg

Question 4

sensitivity

specificity

Answer 4

sensitivity:
100% sensitivity rules out disease, low false-negative rate
= 1-false negative rate

cut-off values:
LOWERING cutoff point - increased sensitivity, decreased specificity, increased NPV, decreased PPV (more positive tests)

Question 5

likelihood ratio (?)

Answer 5

positive LR = TP rate/FP rate

pos LR > 10
neg LR < 0.1

Question 6

risk

Answer 6

attributable risk - difference in risk between exposed and unexposed groups
= (risk in exposed - risk in unexposed)/risk in exposed

absolute and relative risk reduction

NNT = 1/ARR

NNH = 1/AR (of disease with expsoure)

Question 7

prevalence and incidence

Answer 7

prevalence/(1-prevalence) = incidence rate x avg duration of disease

Question 8

precision

Answer 8

aka reliability

increased precision –> lower SD, increased statistical power (1-b)

Question 9

kids in cars

Answer 9

kids < 12 should not ride in a set with a front-facing airbag

Question 10

medicare

Answer 10

65+

<65 with certain disabilities and ESRD

Question 11

suicidal pt

Answer 11

if serious - suggest pt stay in hospital voluntarily

- pt can be hospitalized involuntarily if he/she refuses

Question 12

pt is angry about the delay

Answer 12

apologize

stay away from efforts to explain the delay

Question 13

kids

Answer 13

infant (0-12 mo) = Parents Start Observing

• primitive reflexes disappear
• posture
• picks and pincer grasp, points
• social smile, stranger anxiety, separation anxiety
• orients to voice/name/gestures
• object permanence
• mama, dada by 10 mo

toddler (1-3) - Child Rearing Working

• cruises, climbs stairs, cutlery, kicks ball
• recreation (parallel play), rapproachment (to and from mom), realization of gender (by 36 mo)
• words - 200 words by age 2, 2-word sentences

preschool (3-5) - Dont Forget theyre still Learning

• drives tricycle, drawings, dexterity
• freedom, friends (cooperative play)
• language - 1000 words by age 3
• legends - story telling

ages 5-7 - begin to understand that death is permanent

Question 14

consent for minors

Answer 14

minor < 18

parental consent is not required for sex (contraception, pregnancy), drugs (substance abuse), emergency/trauma

abortion:
many states require parental notification or consent for minors for an abortion

Question 15

biases

Answer 15

confounding bias - cross-over studies, etc. to reduce bias

latent period
- example - antioxidants reduce risk with 5 years…

Question 16

standard error

Answer 16

= SD/square root of sample size

estimate of variability of sample means around the TRUE population mean

Question 17

distributions

Answer 17

positive skew = data concentrated on left

mean > median > mode

Question 18

incorrect results

Answer 18

type 1 error - stating there is an effect/difference when none exists
a is probability of making a type 1 eorr

type 2
b is the probability of making a type 2 error
power = 1-b, power is the probability of rejecting the null hypothesis when it is false
- increase power by increasing sample size, increasing expected effect size, increasing precision

Question 19

confidence interval

Answer 19

95% CI has a 0.95 probability of containing the true population mean

95% CI = mean + 1.96SE
99% CI = mean + 2.58SE

Question 20

Chi-squared

Answer 20

for categorical outcomes
- can be for 2 or more groups

also used to compare expected frequency of occurrence with observed frequency of occurence

Question 21

competence v.s. capacity

Answer 21

capacity determine by physician, competency determined by judge

Question 22

reportable disease

Answer 22

STIs, hepatitis, food poisoning reported to public officials –> public officials will notify people at risk

Tb, Ebola have mandatory treatment

Question 23

causes of death

Answer 23

less than 1 year - congenital, premie, maternal pregnancy complication

1-14yr - accident, cancer, congenital

15-34 - accident, suicide, homicide

35-44 - accident, cancer, heart disease

45-65 - cancer, heart disease, accident

65+ - heart disease, cancer, chronic respiratory disease

Question 24

PDSA cycle

Answer 24

process improvement model to test change

plan, do, study, act

Question 25

errors

Answer 25

active - wrong IV pump dose entered, immediate error

latent - error waiting to happen, different types of IV pumps used in one hospital

error analysis

• RCA - fishbone
• failure mode and effects analysis - forward-looking approach

Question 26

Berkson’s bias

Answer 26

selection bias when hospitalized patients are the control group

Question 27

HIPAA

Answer 27

consent to share medical info- including with family and friends

when pt is incapacitated - basic info can be shared, in pts best interest