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165 Cards in this Set

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What is a case-control study classified as?
Observational and retrospective
How is a case-control study designed?
Compares a group of people with disease to a group without.

Asks "what happened?"
What is measures in a case-control study?
Odds Ratio (OR): Patients with COPD had higher odds of a history of smoking than those without COPD.
What is a cohort study classified as?
Observational and prospective
How is a cohort study designed?
Compares a group with a given risk factor to a group without to assess whether the risk factor increases the likelihood of disease
What is measured in a cohort study?
Relative risk (RR): Smokers had a higher risk of developing COPD than did nonsmokers
What is a cross-sectional study classified as?
Observational
How is a cross-sectional study designed?
Collects data from a group of people to assess frequency of disease (and related risk factors) at a particular point in time

Asks "what is happening?"
What is measured in a cross-sectional study?
Disease prevalence

Can show risk factor association with disease but does not establish causality
What does a twin concordance study measure?

How?
Measures heritability

Compares the frequency with which both monozygotic twins or both dizygotic twins develop a disease
What does adoption study measure?

How?
Measures heritability and influence of environmental factors

Compares siblings raised by biologic vs adoptive parents
Name 5 kinds of studies
Case-control
Cohort
Cross-sectional
Twin concordance
Adoption
What is a phase I clinical trial?
Small number of patients, usually healthy volunteers

Assesses safety, toxicity, and pharmacokinetics
What is a phase II clinical trial?
Small number of patients with disease of interest

Assesses treatment efficacy, optimal dosing, and adverse reactions
What is a phase III clinical trial?
Large number of patients randomly assigned either to the treatment under investigation of to the best available treatment (or placebo)

Compares new treatment to the current standard of care - More convincing if double-blinded
What is a meta-analysis?

How important is it?

What are its faults?
Pools data from several studies to come to an overall conclusion. Achieves greater statistical power and integrates results of similar studies.

Highest eschelon of clinical evidence.

May be limited by quality of individual studies or bias in study selection
Draw the 2 x 2 box of false/true, positive/negative
P. 61
What is sensitivity?
Proportion of all people with disease who test positive
How do you use sensitivity?
Value approaching 1 is desirable for ruling OUT disease and indicates a low false-negative rate

**SNOUT = SeNsitivity rules OUT

Used for screening in diseases with low prevalence
How do you calculate sensitivity?
= TP/(TP+FN)

= 1 - false-negative rate
What is specificity?
Proportion of all people without disease who test negative
How do you use specificity?
Value approaching 1 is desirable for ruling IN disease and indicates a low false-positive rate

**SPIN = SPecificity rules IN

Used as a confirmatory test after a positive screening test
Explain using HIV testing how to use sensitivity/specificity
Screen with ELISA (sensitive, high false-positive rate, low threshold)

Confirm with Western blot (specific, high false-negative rate, high threshold)
How do you calculate specificity?
= TN/(TN+FP)

= 1 - false-positive rate

If 100% specificity, TN/(TN+FP) = 1
FP = 0 and all positives must be TPs
What is positive predictive value?
Proportion of positive test results that are true positive

Probability that person actually has the disease given a positive test result
How do you calculate PPV?
= TP/(TP+FP)
What extra do you need to think about with PPV and how it relates to sensitivity/specificity?
If the prevalence of a disease is low, even tests with high specificity or high sensitivity will have low PPV
What is negative predictive value?
Proportion of negative test results that are true negative

Probability that person is actually disease free given a negative test result
How do you calculate NPV?
= TN/(FN+TN)
What is the equation for point prevalence?
Total cases in population at a given time / total population at risk at a given time
What is the equation for incidence?
New cases in population over a given time period / total population at risk during that time

**Incidence is new incidents - people previously positive for a disease are no longer considered at risk
How do prevalence and incidence relate?
Prevalence = incidence x disease duration

(Roughly)

Prevalence > incidence for chronic diseases
Prevalence = incidence for acute disease
What is odds ratio?
OR for case control studies: odds of having disease in exposed group divided by odds of having disease in unexposed group

= a/b / c/d = ad/bc

See p. 62
What is relative risk?
Relative risk for cohort studies: relative probability of getting a disease in the exposed group compared to the unexposed group

Calculated as percent with disease in exposed group divided by percent with disease in unexposed group = a/(a+b) / c/(c+d)

See p. 62
What is attributable risk?
The difference in risk between exposed and unexposed groups, or the proportion of disease occurences that are attributable to the exposure

Ex. Smoking causes 1/3 cases of pneumonia
What is precision?
The consistency and reproducibility of a test (reliability)

The absence of random variation in a test
What is accuracy?
Trueness of test measurements (validity)
What does random error cause?
Reduced precision in a test
What does systematic error cause?
Reduced accuracy in a test
Draw the targets of accuracy, precision, accuracy and precision, neither
P. 62
What does bias occur?
When 1 outcome is systematically favored over another

Systematic errors
Name 9 kinds of bias
Selection
Recall
Sampling
Late-look
Procedure
Confounding
Lead-time
Pygmalion
Hawthorne effect
What is selection bias?
Nonrandom assignment to study group
What is recall bias?
Knowledge of presence of disorder alters recall by subjects
What is sampling bias?
Subjects are not representative to general population; therefore, results are not generalizable
What is late-look bias?
Information gathered at an inappropriate time
What is procedure bias?
Subjects in different groups are not treated the same
What is confounding bias?
Occurs with 2 closely associated factors; the effect of 1 factor distorts or confuses the effect of the other
What is lead-time bias?
Early detection confused with increased survival
What is Pygmalion effect?
Occurs when a researcher's belief in the efficacy of a treatment changes the outcome of the treatment
What is the Hawthorne effect?
Occurs when the group being studied changes its behavior to meet the expectations of the researcher
Name 4 ways to reduce bias
Blind studies (double-blind even better)
Placebo responses
Crossover studies (each subject is his own control)
Randomization
Draw and define normal distribution
P. 63

Gaussian
Bell shaped
Mean = median = mode
Draw and define bimodal distribution
P. 63

2 humps
Draw and define positive skew
P. 63

Mean > Median > Mode
Assymetry with tail on right
Draw and define negative skew
P. 63

Mean < Median < Mode
Assymetry with tail on left
What is least affected by outliers?
Mode
What is the null hypothesis?
Hypothesis of no difference
What is the alternative hypothesis?
Hypothesis that there is some difference
Draw the 2 x 2 box of statistical hypotheses
P. 63
What is a Type I (alpha) error?
Stating that there IS an effect or difference when there isn't

Mistakenly accept the hypothesis and reject the null hypothesis

"False-positive" error - convicted an innocent man
How does p relate to a Type I error?
p = probability of making a type I error

p is judged against alpha, a present level of significance (usually .05)
What is a Type II (beta) error?
Stating that there is NOT an effect or difference when one exists

Fail to reject the null hypothesis when you should have

"False-negative" error - set a guilty man free
What is power?
Probability of rejecting null hypothesis when it is in fact false, or the likelihood of finding a difference if one in fact exists
What 3 things does power depend on?
Total number of end points experienced by population

Difference in compliance between treatment groups (differences in mean values between groups)

Size of expected effect
How do you calculate power?
1 - beta
How do std dev and std error compare?
SEM = std dev/ square root of sample size

SEM < std dev
SEM decreases as n increases
Draw the normal (Gaussian) distribution with std devs
P. 64
68%
95%
99.7%
What is a confidence interval?
Range of values in which a specified probability of the means of repeated samples would be expected to fall
How is a confidence interval calculated?
CI = range from [mean - Z(SEM)] to [mean + Z(SEM)]

For the 95% CI, Z = 1.96

If the 95% CI for a mean difference includes 0, then there is no significant difference and null hypothesis is not rejected

If the 95% CI for odds ratio or relative risk includes 1, null hypothesis is not rejected
What does a t-test measure?
Difference between means of 2 groups

**Mr. T is MEAN
What does ANOVA measure?
Difference between means of 3 or more groups
What does chi-squared measure?
Difference between 2 or more percentages or proportions of categorical outcomes (not mean values)
What is a correlation coefficient, r?
Always between -1 and 1

Closer the absolute value is to 1, the stronger the correlation between the 2 variables
What is the coefficient of determination?
r^2

This is how correlation coefficient is usually reported
What is primary prevention?
Prevent disease occurrence

Ex. vaccination
What is secondary prevention?
Early detection of disease

Ex. Pap smears
What is tertiary prevention?
Reduce disability from disease

Ex. Exogenous insulin for diabetes
Name some important preventions for diabetes
Eye, foot exams
Urine tests
Name some important preventions for drug use
Hepatitis immunizations
HIV, TB tests
Name some important preventions for alcoholism
Influenza, pneumococcal immunizations
TB test
Name some important preventions for overweight
Blood sugar test
Name some important preventions for homeless, recent immigrant, inmate
TB test
Name some important preventions for high-risk sexual behavior
HIV
Hep B
Syphilis
Gonorrhea
Chlamydia
Name 14 reportable diseases
** Hep, Hep, Hep, Hooray, the SSSMMART Chick is GONe!

Hep A, Hep B, Hep C, HIV, Salmonella, Shigella, Syphilis, Syphilis, Measles, Mumps, AIDS, Rubella, TB, Chickenpox, Gonorrhea
Name 5 leading causes of infant death in US
Congenital anomalies
Short gestation/low birth weight
SIDS
Maternal complications of pregnancy
Respiratory distress syndrome
Name 5 leading causes of death in US of 1-14 year olds
Injuries
Cancer
Congenital anomalies
Homicide
Heart disease
Name 5 leading causes of death in US of 15-24 year olds
Injuries
Homicide
Suicide
Cancer
Heart disease
Name 5 leading causes of death in US of 25-64 year olds
Cancer
Heart disease
Injuries
Suicide
Stroke
Name 5 leading causes of death in US of 65+ year olds
Heart disease
Cancer
Stroke
COPD
Pneumonia
Influenza
What are Medicare Parts A and B?
A = hospital
B = doctor bills
Name 4 core ethical priniciples
Autonomy
Beneficence
Nonmaleficence
Justice
What is autonomy?
Obligation to respect patients as individuals and to honor their preferences in medical care
What is beneficence?
Physicians have special ethical (fiduciary) duty to act in patient's best interest

May conflict with autonomy - ultimately, patient has right to decide
What is nonmaleficence?
"Do no harm"
What is justice?
To treat persons fairly
Name 3 parts of informed consent
Discussion of pertinent information
Patient's agreement to plan
Freedom from coercion
Name 4 exceptions to informed consent
Patient lacks decision-making capacity or is legally incompetent

Implied consent in emergency

Therapeutic privilege - withholding information when disclosure would severely harm the patient of undermine informed decision-making capacity

Waiver - patient waives right to informed consent
Name 5 components of decision-making capacity
Patient makes and communicates a choice

Patient is informed

Decision remains stable over time

Decision is consistent with patient's values and goals

Decision is not a result of delusions or hallucinations
What is oral advance directive?
Incapacitated patient's prior oral statements commonly used as a guide

Problems arise from variance in interpretation
What makes oral advance directive more valid?
Patient was informed
Directive is specific
Patient made a choice
Decision was repeated over time
Name 2 kinds of written advance directives
Living will
Durable power of attorney
What is a living will?
Describes kinds of treatments patient wishes to receive or to not receive
What is a durable power of attorney?
Patient designates a surrogate to make medical decisions
Name 4 exceptions to confidentiality
Potential harm to others is serious
Likelihood of harm to self is great
No alternative means exist to warn/protect others
Physicians can take steps to prevent harm
Name 5 examples of confidentiality exceptions
Infectious diseases
Tarasoff decision - potential victim
Child/elder abuse
Impaired automobile drivers
Suicidal/homicidal patients
Name 4 parts of malpractice negligence
4 D's
Duty
Dereliction
Damage
Direct
What is the Good Samaritan law?
Relieves health care workers from liability in certain situations
What to do when patient is noncompliant?
Work to improve relationship
What to do when family members ask for info
Avoid discussing without permission of patient
What to do if a 17 year old girl asks for abortion
Many states require parental notification or consent for minors

Parental consent not required for medical care during pregnancy
What does APGAR stand for?
Appearance: Blue/trunk pink/all pink
Pulse: None/ < 100/min / > 100/min
Grimace: None/ Grimace/ Grimace and cough
Activity: Limp/ Some/ Active
Respiration: None/ Irregular/ Regular

Evaluate at 1 and 5 minutes
What is low birth weight?
Defined as < 2500 g

Caused by prematurity or intrauterine growth retardation
Name 5 complications of low birth weight
Infections
Respiratory distress syndrome
Necrotizing enterocolitis
Intraventricular hemorrhage
Persistent fetal circulation
Name a motor and cognitive/social milestone for birth-3 months
Rooting reflex
Orients to voice
Name a motor and cognitive/social milestone for 3 months
Holds head up, Moro reflex disappears
Social smile
Name a motor and cognitive/social milestone for 4-5 months
Rolls front to back, sits when propped
Recognizes people
Name a motor and cognitive/social milestone for 7-9 months
Sits alone, crawls
Stranger anxiety
Name a motor milestone for 12-14 months
Upgoing Babinski disappears
Name a motor and cognitive/social milestone for 15 months
Walks
Few words, separation anxiety
Name a motor and cognitive/social milestone for 12-24 months
Climbs stairs, stacks 3 blocks
Object permanence; 200 words and 2-word sentences at age 2
Name a motor and cognitive/social milestone for 18-24 months
Stacks 6 blocks
Rapprochement
Name a cognitive/social milestone for 24-48 months
Parallel play
Name a cognitive/social milestone for 24-36 months
Core gender identity
Name a motor and cognitive/social milestone for 30-36 months
Stacks 9 blocks (number of blocks stacked = age in years x 3)
Toilet training (Pee at 3)
Name a motor and cognitive/social milestone for 3 yrs old
Rides tricycle, copies line or circle drawing
900 words and complete sentences
Name a motor and cognitive/social milestone for 4 years old
Simple drawings (stick figure), hops on 1 foot, copies a cross

Cooperative play, imaginary friends, grooms self, brushes teeth, buttons and zips
Name a motor and cognitive/social milestone for 6-11 years old
Rides bicycle, copies a triangle (age 6)

Reads, understands death, development of conscience, same-sex friends, identification with same-sex parent
Name a cognitive/social milestone for 11 years old (girls) and 13 years old (boys)
Abstract reasoning (formal operations)
Formation of personality
Name the Tanner stages
1. Childhood
2. Pubic hair begins to develop (adrenarche), increased size of testes, breast tissue
3. Increased pubic hair, darkens, curly, increase in penis size/length
4. Increase in penis width, darker scrotal skin, development of glans, raised areolae
5. Adult; areolae are no longer raised
Name 8 categories of changes in the elderly
Sexual changes
Sleep patterns
Common medical conditions
Psychiatric disorders lower prevalence
Increased suicide rate
Decreased vision, hearing, immune response, bladder control
Decreased renal, pulmonary, GI function
Decreased muscle mass, increased fat
What sexual changes occur in the elderly?
Men - slower erection/ejaculation, longer refractory period

Women - vaginal shortening, thinning, and dryness

No change in sexual interest
What sleep changes occur in the elderly?
Decreased REM sleep
Decreased slow-wave sleep
Increased sleep latency
Increased awakenings during night
What 4 common medical conditions occur in the elderly?
Arthritis
Hypertension
Heart disease
Osteoporosis
How does the suicide rate change in the elderly?
Increased
Men 65-74 have highest rate in US
What is grief?
Normal bereavement characterized by shock, denial, guilt, and somatic symptoms

6 months - 1 year
What is pathologic grief?
Excessively intense or prolonged grief or grief that is delayed, inhibited, or denied

May experience depressive symptoms, delusions, and hallucinations
Name the 5 Kubler-Ross grief stages
Denial
Anger
Bargaining
Grief (depression)
Acceptance
Name 9 effects of stress
Production of:
Dree fatty acids
17-OH corticosteroids (immunosuppression)
Lipids
Cholesterol
Catecholamines
Affects water absorption, muscular tonicity, gastrocolic reflex, and mucosal circulation
Name 3 differential diagnoses for sexual dysfunction
Drugs (antihypertensives, neuroleptics, SSRIs, ethanol)
Diseases (depression, diabetes)
Psychological (anxiety)
How is BMI measured?
Weight adjusted for height

Weight in kg/ (height in m)^2
What are the different BMI categories?
< 18.5 = underweight
18.5 - 24.9 = normal
25 - 29.9 = overweight
> 30 = obese
Name the sleep stages and how much time is spent in each
1 (5%)
2 (45%)
3-4 (25%)
REM (25%)
What is Stage 1 sleep?
Light sleep
What kind of EEG is seen in Stage 1 sleep?
Theta
What is Stage 2 sleep?
Deeper sleep
Bruxism
What kind of EEG is seen in Stage 2 sleep?
Sleep spindles and K complexes
What is Stage 3-4 sleep?
Deepest, non-REM sleep
Sleepwalking
Night terrors
Bedwetting (slow-wave sleep)
What kind of EEG is seen in Stage 3-4 sleep?
Delta (lowest frequency, highest amplitude)
What is REM sleep?
Dreaming, loss of motor tone, possible a memory processing function, erections, increased O2 use
What kind of EEG is seen in REM sleep?
Beta (highest frequency, lowest amplitude)

**At night, BATS Drink Blood (Beta, Alpha, Theta, Spindle, Delta, Beta)
What kind of EEG is seen in awake/eyes open?
Beta (highest frequency, lowest amplitude)
What kind of EEG is seen in awake/eyes closed?
Alpha
What initiates sleep?
Serotonergic predominance of raphe nucleus key to initiating sleep
What reduces REM sleep?
NE
What causes extraocular movements during REM?
Activity of PPRF
Name 2 drugs used for sleep problems
Benzodiazepines shorten stage 4 sleep - useful for night terrors and sleepwalking

Imipramine - shortens stage 4 sleep, used for enuresis
What happens during REM sleep?
Increased and variable pulse
REM
Increased and variable BP
Penile/clitoral tumescence

Occurs every 90 minutes
What is the principal neurotransmitter involved in REM sleep?
Ach
What happens to REM over time?
Decreases with age
What is narcolepsy?
Disordered regulation of sleep-wake cycles

May include hypnagogic (just before sleep) or hypnopompic (just before awakening) hallucinations

Patient's nocturnal and narcoleptic sleep episodes start off with REM sleep
What is cataplexy?
Loss of all muscle tone following strong emotional stimulus

Can happen to some narcoleptic patients
How do you treat narcolepsy?
Stimulants - amphetamines, modafinil
What drives circadian rhythms?
Suprachiasmatic nucleus of hypothalamus
What does SCN control?
ACTH, prolactin, melatonin, nocturnal NE release

SCN --> NE release --> pineal gland --> melatonin

SCN is regulated by environment (light)