Behavioral Sciences Flashcards
Relative Risk
Equation
When is it used?
What is it?
[a/(a+b)]/[c/(c+d)]
Cohort Studies
(Risk of developing disease in exposed group)/(risk in unexposed group)
Odds Ratio
Equation
When is it used?
What is it?
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)
Observer Bias
Investigator is affected by prior knowledge
Confounding
Exposure-disease relationship can be explained by another variable
Lead-Time Bias
Apparent prolongation of survival because of earlier diagnosis
Recall Bias
Inaccurate pt recall
Selection Bias
Subjects selected biasedly or biased from selective loss of follow up
Case Control Study Mode of investigation Timeframe Design Basic Question Measurement
Observational Retrospective Compare groups of people w/ and w/o disease and look for prior exposure or risk factors "What Happened?" Odds Ratio
Cohort Study Mode of investigation Timeframe Design Basic Question Measurement
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
Cross Sectional Study Mode of investigation Timeframe Design Basic Question Measurement
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
Twin Concordance Study
Design
Measurements
Compares frequency with which monozygotic or dizygotic twins develop the same disease
Measures Heritability
Adoption Study
Design
Measurements
Compares siblings raised by biological vs adoptive parents
Heritability and influence of environmental factors
Clinical Trial
Population involved
Design
What improves study
Experimental study involving humans
Compares therapeutic benefits of 2 or more treatments or treatment and placebo
Randomized, Controlled, and Double Blinded studies are better
Double vs Triple Blind
Double: Patients and Doctors do not know whose getting treatment
Triple: Researchers analyzing data do not know who got treatment
Phase I Clinical Trial
Sample
Purpose
Small # of health volunteers
Assesses safety, toxicity, and pharmacokinetics
Phase II Clinical Trial
Sample
Purpose
Small # of patients w/ disease
Assesses treatment efficacy, optimal dosing, and adverse effects
Phase III Clinical Trial
Sample
Purpose
Large # of patients comparing 2 drugs or placebo
Compares new treatment to current treatment
Phase IV Clinical Trial
Sample
Purpose
Postmarketing surveillance trial of patients after approval
Detects rare or long term adverse effects
Sensitivity Rate of what? Formula (2) Purpose Use
"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
Specificity Rate of what? Formula (2) Purpose Use
"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
Positive Predictive Value
What does it show?
Formula
What does it vary with?
Proportion of + tests that are true positives
a/(a+b)
Varies directly with prevalence or pretest probability: high pretest probability –> high PPV
Negative Predictive Value
What does it show?
Formula
What does it vary with?
Proportion of negative test results that are true negative
d/(c+d)
Varies inversely with prevalence or pretest probability: High pretest probability –> low NPV
Incidents
(New cases over specified period)/(Population at risk)
Prevalence Equations (2)
(Existing cases)/(Population at risk)
Incidence x Average disease duration
Prevalence vs Incidence in chronic disease
Prevalence > Incidence
When are RR and OR equal?
When prevalence is low
Attributable Risk
Equation
What is it?
[a/(a+b)]-[c/(c+d)]
Risk in exposed group - Risk in unexposed group
Absolute Risk Reduction (ARR)
What is it?
c/(c+d) - a/(a+b)
Event rate in placebo minus treatment groups
Number Needed to Treat
What is it?
Equation
Number of pts who need to be treated for 1 patient to benefit
1/(absolute risk)
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)
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
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
Sampling bias
Subjects not representative of the general population
A form of selection bias
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)
Procedure Bias
Subjects in different groups are not treated the same way
Hawthorne effect
Group being studied changes behavior because they know they are being studied
In a normal distribution, how do measurements of central tendency relate?
Mean = Median = Mode
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
SEM
What is it?
How does it vary?
σ/√n
SEM will ↓ as n ↑
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
Negative Skew
How do measurements of central tendency relate?
How does graph look?
Mean < Median < Mode
Asymmetry with longer tail on left
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)
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
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
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
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
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
If the 95% CI for a mean difference between 2 variables includes 0?
There is no significant difference and H0 is accepted
If the 95% CI for OR or RR includes 1…
H0 is not rejected
If the CIs between 2 groups do not overlap…
Significant difference exists
If the CIs between 2 groups overlap…
No significant difference
t-test
Checks differences between the means of 2 groups
ANOVA
Checks difference between the means of 3 or more groups
χ2
Test checks difference between 2 or more percentages or proportions of categorical outcomes (not mean values)
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
Coefficient of determination
r^2
Disease Prevention
Primary
Secondary
Tertiary
“PDR”
Prevent occurrence
early Detection
Reduce disability from disease
Medicare
For the Elderly (≥65)
Medicaid
For the Destitute
Autonomy
Respect pt as individuals and honor their preferences
Beneficence
Fiduciary duty to act in patient’s best interests
Nonmaleficence
Do no harm
Justice
Treat persons fairly
When is parental consent not necessary?
Emancipated (married, self supporting, has children, in the military), Emergency, Contraception, Treating STDs, Pregnancy, Treatment of Drug Addiction
Can the patient’s family require that a doctor withhold information from a patient?
Not if the patient demonstrates decision making capacity
Exceptions to confidentiality
Harm to others, harm to self, and physician can prevent harm
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
A terminally ill pt requests physician assisted suicide
No Way! but can give medically appropriate analgesics that coincidentally shorten the pt’s life
Suicidal patient
Patient can be hospitalized involuntarily
Patient says she feels ugly
Do not offer falsely reassuring statements like “you still look good”
Patient is angry about the wait time
Do not explain delay. Just apologize and acknowledge
Referral fees for study inclusion
Must tell patient
Patient is upset with how another doctor treated them?
Suggest the pt speak directly with the doctor
Patient is upset with how they were treated by office staff
Say you will speak with that person
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
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
Birth to 3 months
Motor
Social
Cognitive
Rooting reflex, holds head up, Moro reflex disappears
Social smile
Orients and responds to voice
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
12 to 15 months
Motor
Social
Cognitive
Walks, Babinsky Sign Disappears
Separation anxiety
Few words
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
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)
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
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.
Sexual changes in the elderly
Interest does not ↓
Men have slower erection, ejaculation, longer refractory period
Women have vaginal shortening, thinning and dryness
Intelligence changes in the elderly
Intelligence does not decrease
How age changes sleep patterns
↓ REM and slow-wave sleep. ↑ latency and awakening
Psychological changes in the elderly
↑ suicide rates
Men 65-74 have highest rates in US
Organ system changes with age
↓ Vision, Hearing, Immune response, Bladder control, Renal, Pulmonary, GI
↓ muscle, ↑ fat
Grief
What is it characterized by
Length
Shock, Denial, Guilt, Somatic symptoms. May experience illusions
Up to 1 year
Pathologic Grief
What is it?
What may they experience
Excessive, prolonged (>1 year), delayed, inhibited, or denied grief
May experience depression, delusions, and hallucinations
Sexual Dysfunction DDx
Drugs, Disease (depression, diabetes), Psychological
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
Awake with Eyes Open
Description
EEG
Alert and active
Beta (highest frequency, lowest amplitude)
Awake with Eyes Closed
EEG
Alpha
Stage N1 sleep
Percent of sleep
Description
EEG
5%
Light Sleep
Theta
Stage N2
Percent of sleep
Description
EEG
45%
Deeper sleep; Bruxism
Sleep Spindles and K complexes
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
REM sleep
Percent of sleep
Description
EEG
25%
Dreaming, Loss of motor tone, Memory processing, Erections, ↑ brain O2 use
Beta waves
EEG waveforms in sleep
“BATS Drink Blood”
Beta, Alpha, Theta, Sleep spindles, Delta, Beta
Brain region in initiating sleep
5HT region of Raphe Nucleus
Treatment for Sleep Enuresis
Oral Desmopressin
Preferred over Imipramine
Drugs that reduce REM sleep?
EtOH, Benzodiazepines, Barbituates
Also reduce Delta sleep
Treatment for night terrors and sleepwalking?
Benzodiazepines
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
Sleep patterns of depressed patients
↓ slow wave sleep, REM latency,
↑ REM early in sleep, ↑ total REM sleep
Repeated nighttime awakening
Early-morning awakening
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)
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
SCN regulation
SCN regulated by environment (light)
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
