Usmle - Behavioral Sciences

Front 1

Case-Control Study
Definition and variable measured:

Back 1

1. A retrospective comparison of two groups -- a control group and a disease group -- searching for the existence of a risk factor or factors.| - i.e. smoking histories are compared in a group of women with breast cancer to those in a group of women without breast cancer.||2. Odds ratio -- i.e., that one group will have it, vs. odds that the other will have it.| - Women with breast cancer are twice as likely to have smoked in the past than women without it.

Front 2

Cohort study|Variable measured:

Back 2

Relative risk (RR).| - i.e., our cohort study of two groups of patients, smokers and non-smokers, revealed a 5-fold risk of developing lung cancer.| - Answers the question: "what will happen?"

Front 3

Phase 1 of clinical trials|Design and objectives:

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Prospective study with control group using a **small number of healthy subjects.**| - Objective: determine the toxicity, safety, and pharmacokinetics of the drug.

Front 4

Phase 2 of clinical trials|Design and objectives

Back 4

Prospective study with control group using a small number of sick patients.| - Objective: determine efficacy, optimal dosing, and adverse effects.

Front 5

Phase 3 of clinical trials|Design and objectives:

Back 5

Prospective study using a large number of healthy patients, randomly assigned to the test and control groups.| - Objective: compare new treatment to current standard of care.| - Control group can be given a different, established treatment or a placebo.

Front 6

Phase 4 of clinical trials|Design and objectives:

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Postmarketing surveillance trial of patients after approval of drug.| - Detects rare or long-term adverse effects.

Front 7

Formula for sensitivity

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True positives / (true positives + false negatives)||True positives / Total positives

Front 8

Formula for specificity

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True Negatives / (true negatives + false positives)||True negatives / Total negatives

Front 9

Formula for PPV

Back 9

True Positives / (True positives + False positives)||True positives / Total positive test results|| = the probability that a positive test result is correct.

Front 10

Formula for NPV

Back 10

True negatives / (True negatives + False negatives)||True negatives / Total negatives|| = the probability that a negative test result is correct.

Front 11

In chronic disease, which is greater: prevalence or incidence?

Back 11

In chronic disease, prevalence is greater than incidence because a low rate of new diseases can still result in a relatively hi prevalence.

Front 12

Difference between Odds Ratio and Relative Risk

Back 12

Odds ratio refers to the relative odds that a patient with a risk factor for a disease will also have that disease *right now*.| - It is determined via Case-Control study.||Relative risk refers to the risk that this patient will contract that disease in the future.| - It is determined by Cohort study.

Front 13

Define "Number needed to harm"

Back 13

1 / Attributable Risk

Front 14

Recall bias

Back 14

Occurs when the patient's knowledge that he has a disease alters his answers to study questions.

Front 15

Late-look bias

Back 15

Occurs when patients who have passed away from an illness are therefore excluded from a study of that illness.

Front 16

Pygmalion effect:

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Occurs when a researcher's beliefs regarding the efficacy of a treatment effect the outcome of that treatment| - i.e., the researcher gives more attention to patients who are getting the treatment than to the placebo group.| - compare to Hawthorne effect, in which the subjects are the source of the bias.

Front 17

Define "Power".

Back 17

Power is the probability that when a study claims its findings differ from the null hypothesis, they actually do.

It can also be phrased as the probability of rejecting the null hypothesis when it is in fact false.

= 1 - beta, or 1 - type II error

Front 18

Define Type I Error in clinical studies.

Back 18

This error occurs when the researcher claims that there is a significant difference between the experimental hypothesis and null hypothesis, but there is not one.

Front 19

Define Type II error

Back 19

Occurs when the researcher claims there was no difference between the experimental hypothesis and the null hypothesis.

Front 20

Define Gaussian

Back 20

The type of distribution in which mean = median = mode

Front 21

Define positive skew

Back 21

Mean > median > mode
- Distribution in which there is a tail on the positive side of the curve.

Front 22

Which measurement of central tendency changes the least as skew increases?

Back 22

Mode changes the least, b/c the value that corresponds to the greatest number of subjects doesn't really move much.

Front 23

What information do we get from standard deviation and standard error?

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The former tells us how widely a population varies.||The latter gives us an estimate of the quality of the sample.

Front 24

Standard deviations for the 95th and 99th percentiles?

Back 24

95th percentile = 2.standard deviations|99.7th percentile = 3 standard deviations

Front 25

What percentage of a population fits within 1 standard deviation of the mean?

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68% of the population falls within 1 standard deviation of the mean.

Front 26

Which statistical test would we use to compare the means of two different populations? How about 3 different populations?

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For the former, we use a t-test|For the latter, we use ANOVA (Analysis of Variance)

Front 27

Equation for Power

Back 27

1 - beta||Beta = probability that null hypothesis was confirmed mistakenly by results of research.

Front 28

Equation for Confidence Interval

Back 28

Saying that C.I. = 95% is the same as saying that we expect 95% of the population to fall within 2 standard error measurements of the mean in either direction.||CI = [mean - Z(SEM)] through [mean + Z(SEM)]||SEM = Standard deviation / (square root of n)

Front 29

How do we use the chi-square test?

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The chi-square test is used to check the differences between 2 or more percentages or proportions of categorical outcomes.| - i.e., tests the difference between proportions of pt's with bodyweight > 140 between groups A, B, and C at a given time.

Front 30

What are the degrees of disease prevention?

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PDR:
1st degree: Prevention, i.e. via lifestyle changes
2nd degree: Early diagnosis, i.e. by pap smear
3rd degree: Reduction of disability, i.e. by cytoxin treatment!

Front 31

What is a "living will"?

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This term designates a written advanced directive specifying what sorts of treatments and procedures we are to receive or not receive in the event that the patient becomes incapacitated and cannot speak for himself.

Front 32

How much should we tell a curious child about her illness?

Back 32

In this situation, the parents make the determination, not us.

Front 33

What are the parameters of an Apgar assessment?

Back 33

This assessment of newborns is made at 1 and 5 minutes after birth. It scores the child's health based on:
1. Appearance
- coloration of body and extremities, signifying quality of ventilation
2. Pulse
3. Grimace (reflex irritability):
- poke child on foot, 1 point for a grimace, 2 for withdrawal of foot
4. Activity (muscle tone)
- no motion, weak motion, strong kicking
5. Respiration
- no breathing, weak/slow breathing, rapid breathing & crying.

Front 34

How is an Apgar assessment interpreted?

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The APGAR assessment, given once at 1 minute and once at 5 minutes, each time gives us a score between 1 and 10 for a newborn child.||Interpretation of results:| - 10-7 is normal| - 4-6 = "assist and stimulate"| - Less than 4 indicates imminent danger of death.

Front 35

Moro reflex

Back 35

When startled, the child extends arms and legs. This reflex disappears by 3-4 months of age.

Front 36

Milestones of early development
0-3 months:

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1. Rooting reflex
2. Moro reflex disappears
3. Can hold head up

Front 37

At what ages do children typically begin to experience stranger anxiety?

Back 37

7-9 months.

Front 38

At what ages do children typically lose the Moro reflex?

Back 38

At 3-4 months, children cease to reflexively extend arms and legs when startled.

Front 39

At what ages do children typically lose the rooting reflex?

Back 39

At 3-4 months, children cease to reflexively turn their head in the direction of a stroke on the cheek. This reflex serves to bring them to the nipple.

Front 40

At what ages do children typically begin to show a social smile?

Back 40

At about 3 months of age, children begin to smile.

Front 41

At what age does a child become able to transfer toys from hand-to-hand?

Back 41

At about 7-9 months of age, children begin to show more complex motor behaviors such as this.

Front 42

At what age does a child begin to walk?

Back 42

Children develop this ability at about 12-15 months of age.

Front 43

At what age do children begin to manifest separation anxiety?

Back 43

Children begin to manifest this emotional response at 12-15 months of age.

Front 44

At what age do children begin to develop their core gender identity?

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Children begin to develop their core gender identity at 24-36 months of age.

Front 45

At what age do children typically begcome capable of riding a tricycle?

Back 45

At 3 y/o, children typically become able to participate in this more complex form of play.

Front 46

How many words does a 3 y/o's vocabulary typically contain?

Back 46

At this age, a child can speak about 900 words and can make complete sentences.

Front 47

How many words does a child's vocabulary typically have between 12 and 24 months of age?

Back 47

At this age, a child typically can speak about 200 words.

Front 48

At what point does grieving become considered pathological?

Back 48

more than 2 months.

Front 49

In what age group is suicide most common?

Back 49

Males age 65-74 have the highest rate of suicide in the U.S.

Front 50

Define BMI, and its normal ranges.

Back 50

1. kg / m^2|2. Ranges:|18.5 > underweight|18.5 - 24.9 = normal|25 - 29.9 = overweight|30 - 39.9 = Obese|40 < Morbid obesity

Front 51

What are the brain waves corresponding with each stage of sleep?

Back 51

beta waves: REM & Awake

alpha waves: Awake with eyes closed

theta waves: Stage 1

Sleep spindles and bruxism: Stage 2

delta waves: Stage 3

Front 52

What is the principle neurotransmitter in REM sleep, and where is it acting?

Back 52

ACh is the principle neurotransmitter in this form of sleep.|ACh hyperactivity is seen in the reticular formation.

Front 53

What is the most common pathological sleep symptom in depressed patients?

Back 53

Early waking is the most common sleep symptom in these patients.

Front 54

Activity in what brain center is responsible for eye activity during REM sleep?

Back 54

Hyperactivity in the PPRF is associated with the eye movements characteristic of REM.

Front 55

How does depression affect REM sleep?

Back 55

Depression decreases REM latency, while increasing total time spent in REM sleep in these patients. It also increases the amount of time spent in REM early in the sleep cycle.| - *REM latency is the amount of time it takes for the patient to enter REM after falling asleep.

Front 56

Which brain center is responsible for circadian rhythms?

Back 56

The Suprachiasmatic nucleus of the hypothalamus is responsible for this function.

Front 57

Bulemia symptoms:

Back 57

Eroded tooth enamel
25% present with enlarged parotid glands
Irregular menses

Front 58

What psychiatric complications of childbirth are common, and in what time frames?

Back 58

Maternity Blues: more than half of women, resolves within 10 days.

Hint 58

Post-partem depression: 10-20% of women, occurs anywhere from 2 weeks to 1 year post-partem.

Front 59

When is it OK to discuss patient information with the patient's spouse? Is it always OK?

Back 59

Only when he is incapacitated.