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USMLE STEP 1 > Behavioral Sciences > Flashcards

Behavioral Sciences Flashcards

1
Q

Relative Risk
Equation
When is it used?
What is it?

A

[a/(a+b)]/[c/(c+d)]
Cohort Studies
(Risk of developing disease in exposed group)/(risk in unexposed group)

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2
Q

Odds Ratio
Equation
When is it used?
What is it?

A

ad/bc
Case-Control Studies
Odds that the group with the disease was exposed to risk factor (a/c)/(Odds that the group without disease was exposed (b/d)

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3
Q

Observer Bias

A

Investigator is affected by prior knowledge

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4
Q

Confounding

A

Exposure-disease relationship can be explained by another variable

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5
Q

Lead-Time Bias

A

Apparent prolongation of survival because of earlier diagnosis

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6
Q

Recall Bias

A

Inaccurate pt recall

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7
Q

Selection Bias

A

Subjects selected biasedly or biased from selective loss of follow up

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8
Q 
Case Control Study
Mode of investigation 
Timeframe 
Design 
Basic Question 
Measurement
A 
Observational 
Retrospective 
Compare groups of people w/ and w/o disease and look for prior exposure or risk factors 
"What Happened?"
Odds Ratio
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9
Q 
Cohort Study 
Mode of investigation 
Timeframe 
Design 
Basic Question 
Measurement
A 
Observational 
Prospective or Retrospective 
Compare a group with a given exposure or risk factor to a group w/o it and look if exposure ↑ likelihood 
Who will or Who has developed disease 
Relative Risk
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10
Q 
Cross Sectional Study
Mode of investigation 
Timeframe 
Design 
Basic Question 
Measurement
A

Observational
Right Now
Collect data from a group of people to assess frequency of disease and relative risk at a particular point in time
“What is happening?”
Prevalence, Relative Risk, Can show Risk Factor Association but not causality

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11
Q

Twin Concordance Study
Design
Measurements

A

Compares frequency with which monozygotic or dizygotic twins develop the same disease
Measures Heritability

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12
Q

Adoption Study
Design
Measurements

A

Compares siblings raised by biological vs adoptive parents

Heritability and influence of environmental factors

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13
Q

Clinical Trial
Population involved
Design
What improves study

A

Experimental study involving humans
Compares therapeutic benefits of 2 or more treatments or treatment and placebo
Randomized, Controlled, and Double Blinded studies are better

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14
Q

Double vs Triple Blind

A

Double: Patients and Doctors do not know whose getting treatment
Triple: Researchers analyzing data do not know who got treatment

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15
Q

Phase I Clinical Trial
Sample
Purpose

A

Small # of health volunteers

Assesses safety, toxicity, and pharmacokinetics

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16
Q

Phase II Clinical Trial
Sample
Purpose

A

Small # of patients w/ disease

Assesses treatment efficacy, optimal dosing, and adverse effects

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17
Q

Phase III Clinical Trial
Sample
Purpose

A

Large # of patients comparing 2 drugs or placebo

Compares new treatment to current treatment

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18
Q

Phase IV Clinical Trial
Sample
Purpose

A

Postmarketing surveillance trial of patients after approval

Detects rare or long term adverse effects

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19
Q 
Sensitivity 
Rate of what?
Formula (2)
Purpose
Use
A 
"SNOUT - SeNsitivity rules OUT"
"PID - Positive In Disease"
True Positive Rate
a/(a+c) = 1-(false neg rate)
Rules out disease
Used for screening in diseases w/ low prevalence
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20
Q 
Specificity 
Rate of what?
Formula (2)
Purpose
Use
A 
"SPIN - SPecificity rules IN"
"NIH - Negative In Health"
True Negative Rate
d/(d+b) = 1-(false pos rate)
Rules in disease
Confirmatory test after positive screening test
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21
Q

Positive Predictive Value
What does it show?
Formula
What does it vary with?

A

Proportion of + tests that are true positives
a/(a+b)
Varies directly with prevalence or pretest probability: high pretest probability –> high PPV

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22
Q

Negative Predictive Value
What does it show?
Formula
What does it vary with?

A

Proportion of negative test results that are true negative
d/(c+d)
Varies inversely with prevalence or pretest probability: High pretest probability –> low NPV

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23
Q

Incidents

A

(New cases over specified period)/(Population at risk)

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24
Q

Prevalence Equations (2)

A

(Existing cases)/(Population at risk)

Incidence x Average disease duration

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25
Prevalence vs Incidence in chronic disease
Prevalence > Incidence
26
When are RR and OR equal?
When prevalence is low
27
Attributable Risk Equation What is it?
[a/(a+b)]-[c/(c+d)] | Risk in exposed group - Risk in unexposed group
28
Absolute Risk Reduction (ARR) | What is it?
c/(c+d) - a/(a+b) | Event rate in placebo minus treatment groups
29
Number Needed to Treat What is it? Equation
Number of pts who need to be treated for 1 patient to benefit 1/(absolute risk)
30
Number Needed to Harm What is it? Equation
Number of pts who need to exposed to a risk factor for 1 pt to be harmed 1/(attributable risk)
31
Precision What is it? What reduced precision? When precision is increased, what happens?
Consistency and reproducibility of a test. The absence of random variation Random error ↓ precision ↑ precision --> ↓ SD
32
Accuracy What is it? What kind of error does it measure? What reduces accuracy?
Trueness of test measurements (validity) Absence of systematic error or bias in the test Systemic error ↓ accuracy
33
Sampling bias
Subjects not representative of the general population | A form of selection bias
34
Late-Look Bias
Information gathering at an inappropriate time (i.e. survey to study a fatal disease - only those still alive will be able to answer survey)
35
Procedure Bias
Subjects in different groups are not treated the same way
36
Hawthorne effect
Group being studied changes behavior because they know they are being studied
37
In a normal distribution, how do measurements of central tendency relate?
Mean = Median = Mode
38
Standard Deviation What roman numeral? Percentages?
σ (+1σ) and (-1σ) account for 68% of n (-2σ) to (+2σ) account for 95% of n (-3σ) to (+3σ) account for 99.7% of n
39
SEM What is it? How does it vary?
σ/√n | SEM will ↓ as n ↑
40
Positive Skew How do measurements of central tendency relate? Which is least affected? How does graph look?
Mean > Median > Mode Mode is least affected by outliers in the sample Asymmetrical distribution with long tail on right
41
Negative Skew How do measurements of central tendency relate? How does graph look?
Mean < Median < Mode | Asymmetry with longer tail on left
42
Statistical Hypotheses Null Hypothesis Alternative Hypothesis
There is no association between the disease and the risk factors (H0) There is some association between the disease and the risk factor (H1)
43
``` Type I error Symbol What is it? AKA What is used to calculate it? ```
α Error of stating there is a difference when there is not. Accepting H1 and rejecting H0 when H0 is true. False-Positive Error Used to calculate p
44
Type II error Symbol What is it? AKA
β Error that there is not an effect or difference when one exists. Accept H0 when H1 is true False-Negative Error
45
Power Equation What is it? What increases it?
1-β Probability of rejecting H0 when it is false Increases with ↑ Sample Size, Expected Effect Size, and Precision of measurements
46
Meta Analysis What is it? What does it increase? What limits it?
Pools data and integrates results from several similar studies ↑ statistical power Limited by quality of individual studies or bias in each study
47
Confidence Interval Equation Conventions of CI How does it relate to Z
Range of values in which a specified probability of the means of repeated samples would be expected to fall Range from [mean - Z(SEM)] to [mean + Z(SEM)] 95% CI corresponds to p=.05 CI = 95%, Z = 1.96 CI = 99%, Z = 2.58
48
If the 95% CI for a mean difference between 2 variables includes 0?
There is no significant difference and H0 is accepted
49
If the 95% CI for OR or RR includes 1...
H0 is not rejected
50
If the CIs between 2 groups do not overlap...
Significant difference exists
51
If the CIs between 2 groups overlap...
No significant difference
52
t-test
Checks differences between the means of 2 groups
53
ANOVA
Checks difference between the means of 3 or more groups
54
χ2
Test checks difference between 2 or more percentages or proportions of categorical outcomes (not mean values)
55
Pearson's Correlation Coefficient Symbol? What is its range? What does it measure
r -1 to +1 The closer it is to 1, the stronger the linear correlation between 2 variables
56
Coefficient of determination
r^2
57
Disease Prevention Primary Secondary Tertiary
"PDR" Prevent occurrence early Detection Reduce disability from disease
58
Medicare
For the Elderly (≥65)
59
Medicaid
For the Destitute
60
Autonomy
Respect pt as individuals and honor their preferences
61
Beneficence
Fiduciary duty to act in patient's best interests
62
Nonmaleficence
Do no harm
63
Justice
Treat persons fairly
64
When is parental consent not necessary?
Emancipated (married, self supporting, has children, in the military), Emergency, Contraception, Treating STDs, Pregnancy, Treatment of Drug Addiction
65
Can the patient's family require that a doctor withhold information from a patient?
Not if the patient demonstrates decision making capacity
66
Exceptions to confidentiality
Harm to others, harm to self, and physician can prevent harm
67
A 17 year old girl is pregnant and requests an abortion
Many states require parental notification or consent for minors for an abortion. Unless she is at medical risk, do not advise pt to have an abortion regardless of her age or condition of the fetus
68
A terminally ill pt requests physician assisted suicide
No Way! but can give medically appropriate analgesics that coincidentally shorten the pt's life
69
Suicidal patient
Patient can be hospitalized involuntarily
70
Patient says she feels ugly
Do not offer falsely reassuring statements like "you still look good"
71
Patient is angry about the wait time
Do not explain delay. Just apologize and acknowledge
72
Referral fees for study inclusion
Must tell patient
73
Patient is upset with how another doctor treated them?
Suggest the pt speak directly with the doctor
74
Patient is upset with how they were treated by office staff
Say you will speak with that person
75
``` APGAR score Time What is it? What do scores mean? What if the score is low? ```
1 minute and 10 minutes Appearance, Pulse, Grimace, Activity, Respiration Greater than or Equal to 7 is good. 4-6: assist and stimulate Less than 4: resuscitate If <4, there is ↑ risk of long term neurological damage
76
``` Low Birth Weight Definition What causes it? Increased risk for what? Other problems? Complications? ```
Less than 2500g Prematurity or intrauterine growth retardation "PREME C SHIT" ↑ risk for SIDS and overall mortality Impaired thermoregulation and immune function, Hypoglycemia, Polycythemia, Impaired neurocognitive/emotional development Infections, RDS, Necrotizing enterocolitis, Intraventricular hemorrhage, persistent fetal circulation
77
Birth to 3 months Motor Social Cognitive
Rooting reflex, holds head up, Moro reflex disappears Social smile Orients and responds to voice
78
7 to 9 months Motor Social Cognitive
Sits alone, Crawls, Transfers toys from hand to hand Stranger anxiety Responds to name and simple instructions, uses gestures, plays peek-a-boo
79
12 to 15 months Motor Social Cognitive
Walks, Babinsky Sign Disappears Separation anxiety Few words
80
12 to 24 months Motor Social Cognitive
Climbs stairs, Stacks 3 blocks at 1 year, Stacks 6 blocks at 2 years Rapprochement 200 words. 2 word phrases at age 2
81
24 to 36 months Motor Social Cognitive
Feeds self with fork and spoon. Kicks ball Core gender identity. Parallel play Toilet training (pee at 3)
82
3 years old Motor Social Cognitive
Rides tricycle (3 cycle at 3). Copies line or circle drawings Comfortably spends part of the day away from mother 900 words. Complete sentences
83
4 years Motor Social Cognitive
Uses buttons and zippers, Grooms self, Hops on 1 foot, Makes simple drawings Cooperative play, Imaginary friends Can tell detailed stories and uses prepositions.
84
Sexual changes in the elderly
Interest does not ↓ Men have slower erection, ejaculation, longer refractory period Women have vaginal shortening, thinning and dryness
85
Intelligence changes in the elderly
Intelligence does not decrease
86
How age changes sleep patterns
↓ REM and slow-wave sleep. ↑ latency and awakening
87
Psychological changes in the elderly
↑ suicide rates | Men 65-74 have highest rates in US
88
Organ system changes with age
↓ Vision, Hearing, Immune response, Bladder control, Renal, Pulmonary, GI ↓ muscle, ↑ fat
89
Grief What is it characterized by Length
Shock, Denial, Guilt, Somatic symptoms. May experience illusions Up to 1 year
90
Pathologic Grief What is it? What may they experience
Excessive, prolonged (>1 year), delayed, inhibited, or denied grief May experience depression, delusions, and hallucinations
91
Sexual Dysfunction DDx
Drugs, Disease (depression, diabetes), Psychological
92
BMI Formula #s
(Wt in kg)/(Height in meters)^2 Less than 18.5 is underweight 25 to 29.9 is overweight Greater than 30 is obese
93
Awake with Eyes Open Description EEG
Alert and active | Beta (highest frequency, lowest amplitude)
94
Awake with Eyes Closed | EEG
Alpha
95
Stage N1 sleep Percent of sleep Description EEG
5% Light Sleep Theta
96
Stage N2 Percent of sleep Description EEG
45% Deeper sleep; Bruxism Sleep Spindles and K complexes
97
``` Stage N3 Percent of sleep Description EEG What can happen during this stage? ```
25% Deepest non REM sleep Delta waves (low frequency, high amplitude). Slow wave sleep Sleepwalking, night terrors, bedwetting
98
REM sleep Percent of sleep Description EEG
25% Dreaming, Loss of motor tone, Memory processing, Erections, ↑ brain O2 use Beta waves
99
EEG waveforms in sleep
"BATS Drink Blood" | Beta, Alpha, Theta, Sleep spindles, Delta, Beta
100
Brain region in initiating sleep
5HT region of Raphe Nucleus
101
Treatment for Sleep Enuresis
Oral Desmopressin | Preferred over Imipramine
102
Drugs that reduce REM sleep?
EtOH, Benzodiazepines, Barbituates | Also reduce Delta sleep
103
Treatment for night terrors and sleepwalking?
Benzodiazepines
104
``` REM sleep When does it occur? Duration Change with age? Neurotransmitters involved Findings ```
``` Every 90 minutes Duration ↑ throughout night ↓ frequency with age ACh --> REM. NE --/ REM ↑ and variable BP and HR. EOM (activity of PPRF), Penile/Clitoral Tumescence ```
105
Sleep patterns of depressed patients
↓ slow wave sleep, REM latency, ↑ REM early in sleep, ↑ total REM sleep Repeated nighttime awakening Early-morning awakening
106
``` Narcolepsy What is it? Presentation Sleep cycle Genetics Treatment ```
Disordered regulation of sleep-wake cycles Daytime sleepiness, Hallucinations (right before or after sleep), Cataplexy following strong emotional stimulus. Cannot move when you wake up in the morning REM at beginning of sleep Strong genetic components Daytime stimulants (amphetamines, modafinil) and nighttime GHB (sodium oxybate)
107
Circadian Rhythm Brain centers involved What does it control Pathway
Suprachiasmatic nucleus (SCN) of the hypothalamus Controls ACTH, Prolactin, Melatonin, and nocturnal NE release SNC --> NE release --> Pineal gland --> melatonin
108
SCN regulation
SCN regulated by environment (light)
109
``` Sleep Terror Disorder What is it? When does it occur? Population involved Memory Cause Course ```
``` Periods of terror with screaming in the middle of the night Slow-wave, non-REM sleep Children No memory of event emotional distress, fever, lack of sleep Self limited ```

USMLE STEP 1 (25 decks)

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