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59 Cards in this Set
- Front
- Back
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Point Prevalence
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(Total cases in population at a give time)/(total population at a given time)
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Incidence
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(new cases in population over a given time period)/(total population at risk during that time period)
People who are currently with the disease or those previously positive for it are not considered to be part of the population at risk. |
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Prevalence
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Incidence x Disease duration (improved quality of care lengthens the disease duration because the person is less likely to die from it so the prevalence increases)
Prevalence > Incidence for chronic disease Prevalence = Incidence for acute disease |
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Odds Ratio (for case control studies)
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Odds of having disease in exposed group / Odds of having disease in unexposed group.
Approximates RR if prevalence of disease is not too high |
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Relative Risk (for cohort studies)
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% with disease in exposed group / % of disease in unexposed group
Relative probability of getting a disease in the exposed group compared to the unexposed group. |
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Attributable risk
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% with disease in exposed group - % with disease in unexposed group.
Also equal to (RR-1)/RR Measures the proportion of disease occurrences that are attributable to the exposure |
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Absolute risk reduction
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The reduction in risk associated with a treatment compared to a placebo (use attributable risk equation).
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Number Needed to Treat
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1/absolute risk reduction
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Number needed to harm
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1/attributable risk
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Selection bias
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Non random assignment to a study group.
Ex: Berkson's bias- selecting hospitalized patients as control group (they have more symptoms, access to care, population of the hospital, etc) |
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Recall bias
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Knowledge of presence of disorder alters recall by subjects. For example, questioning mothers whose recent pregnancies ended in fetal death or malformation and a matched group whose pregnancies ended normally, it was found that 28% of the former and only 20% of the later reported exposure to drugs. The first group will remember more since their pregnancy ended in miscarriage.
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Sampling bias
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Subjects are not representative relative to the general population, therefore the results are not generalizable.
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Late-look bias
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Information gathered at an inappropriate time.
Ex: Using a survey to study a fatal disease (only those patients still alive will be able to answer the survey). This is a type of recall bias. |
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Procedure bias
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Subjects in different groups are not treated the same.
Ex: More attention is paid to the treatment group, stimulating greater compliance. |
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Confounding bias
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Occurs with 2 closely associated factors; the effect of 1 factor distorts or confuses the effect of the other. Matching can help prevent this and is used in case-control studies.
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Lead-time bias
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Early detection confused with increased survival. This is seen with improved screening (the natural history of the disease is not actually changed, but early detection makes it seem like more people are surviving).
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Pygmalion effect
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Occurs when a researcher's belief in the efficacy of a treatment changes the outcome of that treatment.
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Hawthorne effect
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Occurs when the group being studied changes its behavior owing to the knowledge of being studied.
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Type I error (alpha)
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Stating that there IS an effect or difference when non exists (to mistakenly accept the experimental hypothesis and wrongly reject the null hypothesis). False positive error
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Rho (p)
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The probability of making a type I error. p is judged against a preset level of significance (usually < 0.5). "False positive error"
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Type II error (beta)
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Stating that there is NOT an effect or difference when one exists (to fail to reject the null hypothesis when in fact the null hypothesis is false).
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Beta
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The probability of making a type II error. "False-negative error."
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Power
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1-beta; This is another way of calculating the probability of rejecting the null hypothesis when it is in fact false OR the likelihood of finding a difference if one in fact exists. It depends on the total number of end points experienced by the population, the difference in compliance between the two treatment groups (mean values), and the size of the expected difference. INCREASED SAMPLE SIZE INCREASES POWER!
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Confidence Interval
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The range of values in which a specified probability of the means of repeated samples would be expected to fall.
CI = range from [mean - Z(SEM)] to [mean + Z(SEM)]. Z = 2 for CI = 95%. If the confidence interval between 2 variables includes 0, there is no significant difference and the null hypothesis is not rejected; if the confidence interval for odds ratio or RR includes 1 (RR = 1 means that there is no increased risk), the null hypothesis is not rejected. |
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How does prevalence of a disease affect the evaluation of diagnostic tests?
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PPV- Will increase because it means that more of the people who are testing positive are true positives.
NPV- Will decrease because it means that more of the people who are testing negative are actually false negatives since the disease is so prevalent. Sensitivity and specificity are NOT affected |
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Standard error of mean
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Standard deviation/sqrt (sample size, n)
Therefore, SEM < STD and SEM decreases as n increases |
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What is the difference between the t-test, ANOVA, and chi squared?
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t-test: Checks the difference between the MEANS of 2 groups
ANOVA: Checks the difference between the MEANS of 3 or more groups Chi-squared: Checks the difference between 2 or more PERCENTAGES or proportions of categorical outcomes (NOT means) |
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What are the 3 levels of disease prevention?
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Primary- Prevent occurrence (vaccines)
Secondary- Early detection (Pap smear, mammogram, PSA) Tertiary- Reduce disability (chemotherapy. B-blocker post MI, metmorfin for DM) |
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What are the exceptions to informed consent?
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1. Patient lacks decision making capacity or is legally incompetent
2. Implied consent in an emergency 3. Therapeutic privilege- Withholding information when disclosure would severely harm the patient or undermine informed decision-making. 4. Waiver- patient waives the right of informed consent |
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When is parental consent NOT required?
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If the patient is emancipated (married, military, self-supporting, has children), for STD treatment, prescribing contraceptives, medical care during pregnancy, or drug addiction management
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What are exceptions to confidentiality?
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1. Potential harm to others that is serious.
2. Liklihood of harm to self is great. 3. No alternative means exist to warn or protect those at risk. Examples: Infectious diseases (report to CDC and people at risk), Tarasoff decision- physician is required to directly inform and protect potential victim from harm, Child/elder abuse or suspcion, impaired automobile drivers, suicidal/homicidal patients |
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What are the 4Ds of malpractice?
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Duty, Dereliction (breach of duty), Damage (patient suffers harm), Direct (breach of duty is what caused the harm)
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What happens from birth to 3 months?
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Rooting reflex, orients to voice
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What happens at 3 months?
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Holds head up, Moro reflex disappears, social smile
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What happens between 7-9 months?
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Sits alone, crawls, stranger anxiety
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What happens at 15 months?
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Walks, Babinski disappears, few words, separation anxiety
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What happens between 12-24 months?
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Climbs stairs, stacks 3 blocks at 1 year; 6 blocks at 2 years.
Object permanence; 200 words and 2-word sentences at age 2 |
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What happens between 24-36 months?
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Core gender identity, parallel play
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What happens at 30-36 months?
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Stacks 9 blocks, toilet training (pee at age 3)
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What happens at 3 years?
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Tricycle, copies line/circle drawing, 900 words and complete sentences
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What happens at 4 years?
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Simple drawings, hops on 1 foot, cooperative play, imaginary friends, brushes teeth, buttons and zips!
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What is the sleep pattern of elderly?
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Decreased REM and slow-wave sleep, Increased REM latency and awakenings
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What is the sleep pattern of depression?
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Decreased slow-wave sleep, increased total REM, decreased REM latency, increased REM early in the sleep cycle, repeated nighttime awakenings, early-morning awakening
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What is the DDx for sexual dysfunction?
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1. Drugs- antihypertensives (B-blockers), neuroleptics, SSRIs, ethanol
2. Diseases- atherosclerosis, DM 3. Psychological- performance anxiety |
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What is the EEG wave form when awake with eyes open and alert?
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Beta- highest frequency, lowest amplitude
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What is the EEG wave form when awake with eyes closed?
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Alpha
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What is the EEG wave form when in stage 1 sleep (light sleep- 5% total sleep)
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Theta
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What is the EEG wave form when in deeper sleep; bruxism (stage 2- 45% of total sleep)
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Sleep spindles and K complexes
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What is the EEG wave form when in slow-wave sleep (stage 3-4; 25% of total sleep)
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Delta (lowest frequency, longest highest amplitude)
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What occurs during stage 3-4 sleep?
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Sleepwalking, night terrors, bedwetting
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What is the EEG wave form of REM sleep (25% total sleep)
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Beta
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What occurs during REM sleep?
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Dreaming, loss of motor tone, erections, INCREASED brain O2 use
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What reduces REM sleep?
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NE
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What initiates sleep?
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Serotonin in the raphe nucleus
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What causes the eye movements during REM sleep?
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PPRF- saccades, fast phase nystagmus; remember a lesion makes you look away from the side of the lesion
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What is used to treat enuresis?
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Imipramine- decreases stage 4 sleep
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What can be used to treat night terrors and sleepwalking?
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Benzodiazepines (decrease SWS)
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What is associated with reduced REM and SWS?
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Alcohol, benzodiazepines, barbiturates
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What neurotransmitter is involved in REM sleep?
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ACh
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