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150 Cards in this Set
- Front
- Back
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case-control study
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observational and retrospective
compares a group of people with disease to a group without asks: "What happened" measures: Odds ratio: "patients with COPD had higher odds of a history of smoking with those without COPD" |
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What type of study asks what happened?
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case-control study
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Cohort study
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observational and prospective
compares a group with a given risk factor to a group without to assess whether the risk factor increases the likelihood of disease measures: relative risk "smokers had a higher risk of developing COPD than nonsmokers" |
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Cross-sectional study
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observational
collects data from a group of people to assess the frequency of disease (and related risk factors) at a particular point in time asks: "what is happening?" measures: disease prevalence can show risk factor association with disease, but does not establish causality |
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What does twin concordance study look at?
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compares frequency with which both monozygotic twins or both dizygotic twins develop a disease
measure heritability |
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What does adoption studies look at?
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compares siblings raised by biological parents vs. adoptive parents
measure heritability and influence of environmental factors |
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clinical trials
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experimental study involving humans. compares therapeutic benefits of 2 or more treatments, or of treatment and placebo. Highest quality study when randomized, controlled, and double-blinded
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What is the highest quality of study?
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One that is randomized, controlled, and double blinded
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Phase I clinical trial
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group of healthy volunteers given a drug - to measure toxicity, safety, and pharmocokinetics
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Phase II clinical trial
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Small number of patients with the disease of interest
assesses treatment efficacy, optimal dosing, and adverse effects |
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Phase III clinical trial
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Large number of patients randomly assigned either to the treatment under investigation or to the best available treatment (or placebo)
Compares new treatment to standard of care. Is more convincing if double blinded (neither patient nor doctor knows if the patient is in the treatment or the control group) |
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meta-analysis
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pools data from several studies to come to an overall conclusion. Achieves greater statistical power and integrates results from similar studies. highest echelon of clinical evidence
- may be limited by quality of individual studies or bias in study selection |
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what type of study has the highest echelon of clinical evidence?
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meta-analysis
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Sensitivity
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If someone has the disease how often do they test positive?
TP/TP+FN *used to test for diseases with a low prevalence |
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Specificity
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If someone does not have the disease how often will they test negative?
TN/TN+FP *used for a confirmatory test after positive screening test |
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HIV testing how is it done?
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1st - ELISA - highly sensitive - but high rate of false positives
SO if test positive then do western blot (very specific, high false negative rate) |
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PPV
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positive predictive value - if you test positive chance that you have the disease
TP/TP+FP *If the prevalence of a disease is low, even test with high specificity or high sensitivity will have low positive predictive value |
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point prevalance
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= total cases in a population at a give time/total number of people in the population at risk
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Incidence
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= new cases in a population over a given time period/ total population at risk during that time
*incidence = new incidents *when measuring incidence - people currently with the disease or those previously positive for it - are not considered at risk |
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prevalence
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prevalence = incidence x disease duration
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prevalence and incidence for a chronic disease
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prevalence > incidence for a chronic disease (diabetes)
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prevalence and incidence for an acute disease
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prevalence = incidence for an acute disease (common cold)
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Odds ratio
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for case-control studies
odds of having the disease in the exposed group divided by odds of having disease in unexposed group = (a/b)/(c/d) = ad/bc |
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Relative risk
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for cohort studies
relative probability of getting a disease in the exposed group compared to the unexposed group = (a/a+b)/c/c+d) = exposed event rate/control event rate |
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attributable risk
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the difference in risk between exposed and unexposed groups, or proportion of disease occurances that are attributable to the exposure (ex. smoking causes 1/3 of cases of pneumonia)
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absolute risk reduction
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reduction in risk associated with a treatment as compared to placebo
= experimental rate of dz - control rate of dz = (a/a+b) - (c/c+d) |
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number needed to treat
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1/absolute risk reduction
*number of patients that must be treated to avoid the outcome |
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number needed to harm
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1/attributable risk
*if intervention leads to more harm than the control |
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Precision
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consistency and reproductibility of a test
- absence of random variation in a test |
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Accuracy
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the trueness of test measurements (validity)
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random error creates what?
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reduced precision in a test
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systemic error creates what?
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reduced accuracy in a test
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When does bias occur?
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when 1 outcome is systemically favored over another. Systemic errors
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What are ways to reduce bias?
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- blind studies (double blind is best)
- placebo responses - crossover studies (each subject acts as its own control) - randomization |
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nonrandom assignment to study group creates what type of bias?
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selection bias - berkson's bias
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knowledge of presence of disorder alters recall by subjects
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recall bias
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subjects are not representative relative to general population; therefore, results are not generalizable
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sampling 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 survey)
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late-look bias
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subjects in different groups are not treated the same - ex. more attention is paid to treatment group, stimulating greater compliance
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procedure bias
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occurs with 2 closely associated factors; the effect of 1 factor distorts or confused the effect of the other
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confounding bias
cases and controls must be match to decrease confounding bias |
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early detection confused with increased survival; seen with improved screening (natural history of disease is not changed, but early detection makes it seem as though increased survival)
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lead time bias
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occurs when researchers belief in the efficacy of a treatment changes the outcome of that treatment
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pygmalion 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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hawthorne effect
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what is the mean, median, and mode in a normal gaussian bell-shaped curve?
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mean = median = mode
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bimodal distribution
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2 humps (2 modal peaks)
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Positive skew on statistical distribution - what does graph look like, mean, median and mode
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asymmetry of graph with tail on right
mean>median>mode |
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Negative skew on statistical distribution what does graph look like? mean, median, mode?
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asymmetry of graph with tail on left
mode>median>mean |
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What is least affected by outliers in a sample?
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mode
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Null hypothesis (H0)
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hypothesis of no difference (there is no association between the disease and the risk factor in the population)
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Alternative hypothesis (H1)
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Hypothesis that there is some difference (there is some association between the disease and the risk factor in the population
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type 1 error (a)
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Stating that there is an effect or difference when none exists (to mistakenly accept the experimental hypothesis and reject the null hypothesis) p = probability of making a type 1 error. p is judged against a, a present level of significance (usually <0.05). False positive error
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what does p<0.05 mean?
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that there is a less than 5% chance that the data will show something that is not really there
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type II (B) error
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stating that there is not a difference when one really does exist. fail to reject the null hypothesis and rejecting the experimental hypothesis
B is the probability of making a type II error - false negative error |
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what is p judged against?
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alpha
p is the probability of making a type 1 error seeing a difference when one does not exist |
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Power
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1-B (B = fail to reject the null hypothesis when there is a difference)
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: 1) total number of end points experienced by population 2) difference in compliance between treatment groups (differences in the mean values between groups) 3) size of expected effect |
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If you increase sample size what happens to power?
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It increases
'There is power in numbers' |
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Standard deviation vs. standard error of mean
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n = sample size
standard error of mean = SEM starndard deviatio = o with tail SEM = standard deviation/square root of the sample size standard deviation is greater than SEM and SEM decreases as the sample size increases |
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What % does 1 SD include?
2 SD's? 3 SD's? |
1 = 68%
2 = 95% 3 = 99.7% |
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confidence interval
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range of values in which a specified probability of the means of repeated samples would be expected to fall
95% CI - means 95% of observations lie within 2 SD from the mean CI = range from (mean - Z(SEM)) to (mean + Z(SEM) for 95% CI use Z = 1.96 95% CI corresponding to p = 0.05 |
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What if the 95% confidence interval for a mean difference between 2 variables includes 0?
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then there is no significant difference and H0 is not rejected
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What if the 95% CI fro odds ratio or relative risk includes 1?
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H0 is not rejected
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If the CI between 2 groups overlaps then what?
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then the groups are not significantly different
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t-test vs. ANOVA vs. x^2
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t-test - difference in means between 2 groups
ANOVA - difference in means between 3 or more groups x^2 checks the difference between 2 or more percentages or proportions of categorical outcomes (not mean values) |
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correlation coefficient (r)
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always between -1 and +1. The closer the absolute value of r is to 1, the stronger the correlation between the 2 variables
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coefficient of determination
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what is usually reported
= r ^2 r = correlation coefficient (between -1 and +1) the closer the absolute value of r is to 1, the stronger the correlation between the 2 variables |
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primary, secondary, tertiary disease prevention
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primary - prevent disease occurrence (HPV vaccination)
secondary - early detection of disease (PAP smear) tertiary - reduce disability from disease (chemotherapy if develop cervical cancer) |
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What are important prevention measure for diabetes?
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eye exams, foot exams; urine tests
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What are important prevention measures for drug use?
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hepatitis immunization, HIV and TB tests
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What are important prevention measure for alcoholism?
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influenza, pneumococcal immunizations; TB test
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What are important prevention measures for obesity?
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blood sugar tests for diabetics
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What are important prevention measures for homeless individuals or recent immigrants?
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TB test
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What are important prevention measures for high-risk sexual behavior?
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HIV, hep B, syphilis, gonorrhea, chlamydia
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What are reportable diseases in all states?
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Hep, Hep, Hep, Hooray, the SSSMMART Chick is Gone
Hep A, Hep B, Hep C, HIV, Salmonella, Shigella, Syphilis, Measles, Mumps, AIDS, Rubella, TB, Chickenpox, Gonorrhea |
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leading cause of death in infants?
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congenital anomalies, short gestation/low birth weight, SIDS, maternal complications of pregnancy, respiratory distress syndrome
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Leading cause of death in children ages 1-14
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injuries, cancer, congenital anomalies,homicide, heart disease
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leading cause of death in children ages 15-24?
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injuries, homicide, suicide, cancer, heart disease
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leading cause of death in individuals age 25-64?
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cancer, heart disease, injuries, suicide, sroke
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leading cause of death in individuals age 65 and older?
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heart disease, cancer, stroke, COPD, pneumonia, influenza
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how does fee-for service payment work?
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physicians get payment for each procedure
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How does capitation basis payment work?
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fixed payment for time period, regarless of number of procdures
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How does salary based payment work?
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hospitals, HMOs, universities pay fixed salary
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Medicare and Medicaid
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federal programs that originated from amendments to the social security act.
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What originated from amendments to the social security act?
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Medicare and Medicaid
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Medicare
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medicarE - for elderly
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Medicaid
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medicaiD - for Destitute (poor)
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Medicare part A and part B
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part A - pays for hospital bills
part B pays for doctors bills, outpatient x-rays, labs, vaccines, equipment, home O2, outpatient nursing |
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CHIP
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children's health insurance program - matching state and federal govement funding for child health care coverage
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Third-party payers
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insurance companies collect money from large population to pay all or a portion of the medical bills of current patients
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Autonomy
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obligation to respect patients as individuals and to honor their preferences in medical care
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Beneficence
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Physicians have a special ethical duty to act in the patients best interest. May conflict with autonomy. If the patient can make an informed decision, ultimately the patient has the right to decide.
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Nonmaleficence
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Do no harm. however, if the benefits of an intervention outweigh the risks, a patient may make an informed decision to proceed (most surgeries fall into this category)
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Justice
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to treat persons fairly
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What does informed consent have to require?
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must legally require:
1) discussion of pertinent information 2) patient's agreement to the plan of care 3) freedom from coercion *patients must understand the risks, benefits, and alternatives, which include no intervention |
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What are some 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 - witholding information when disclosure would severely harm the patient or undermine informed decision-making capacity 4) waiver - patient waves the right of informed consent |
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how does consent for minors work?
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parental consent must be obtained unless minor is emancipated (ex. married, pregnant, self-supporting, has children, is in the military)
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decision making capacity
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1. patient makes and communicates a choice
2. patient is informed 3. decision remains stable over time 4. decision is concistent with patient's values and goals 5. decision is not a result of delusions or hallucinations *Patient's family cannot require that a doctor withhold information from the patient |
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Oral advance directive
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incapacitated patient's prior oral statment commonly used as guuide. Problems arise from variance in interpretation. If the patient was informed, directive is specific, patient made a choice, and decision was repeated over time, the oral directive is more valid
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Living will
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describes treatments the patient wishes to receive or not receive if he/she becomes incapacitated and cannot communicate about treatment decisions. usually the patient directs physician to withhold or withdraw life-sustaining treatment if he/she develops a terminal disease or enters persistent vegetative state
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durable power of attorney
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patient designates a surrogate to make decisions in the event that he/she looses decision making capacity. Person may also specify decisions in clinical situations. Surrogate remains power unless revoked by patient. More flexible than a living will
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confidentiality
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respects patients privacy and autonomy. Disclosing information to family and friends should be guided by what the patient would want. The patient may waive the right to confidentiality (ex. insurance companies)
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Exceptions to confidentiality
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1. potential harm to others is serious
2. likelihood of harm to self is great 3. no alternative means to warm or to protect those at risk 4. physicians can take steps to prevent harm ex. infectious diseases - physicians may have a duty to warm public officials about identifiable people at risk - Tarasoff decision - law requiring physicians to directly inform and protect potential victims from harm; may involve breach of confidentiality - child and/or elder abuse - impaired automobile drivers - suicidal/homicidal patients - physicians may hold patients involuntarily for a period of time |
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Tarsoff decision
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law requiring physicians to directly inform and protect potential victim from harm; may involve a breach of confidentiality
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Malpractice
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civil suit under negligence requires:
1. physician had duty to the patient 2. physician breached that duty (dereliction) 3. patient suffered harm (damage) 4. the breach of duty was what caused the harm (direct) - most common factor leading to litigation is poor communication between physician and patient - burden of proof in malpractice suit is more likely than not |
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What is the most common factor leading to litigation?
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poor communication
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Good samaritan law
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relieves health care workers, as well as laypersons in some instances, from liability in certain emergency situations with the objective of encouraging health care workers to offer assistance without expectation of compensation
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17 year old patient wants an abortion what should you do?
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many states require patrental notification for an abortion
parental consent is not required for emergency situations, treatment of STD's, medical care during pregnancy, management of drug addiction |
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if a child wishes to learn more about their illness what should you do?
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as what the parents have told the child about the illness. parents of a child decide what information can be relayed about the illness
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child under 18 requests condoms
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physicians can provide counsel and contraceptives to minors without a parent's knowledge or consent
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a drug company offers a "referral fee" for every patient a physician enrolls in a study
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patients who may benefit from the study can be enrolled but it is NEVER acceptable for a physician to receive compensations from a drug company
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What is an APGAR score?
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a 10 point scale evaluated at 1 minute and 5 minutes after birth
Appearance - blue (0), trunk pink (1), all pink (2) Pulse - none (0), <100/min (1), >100/min (2) Grimace - none (0), grimace (1), grimace + cough (2) Activity - none (0), some (1), active (2) Respiration - none (0), irregular (1), regular (2) |
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When do the newborn reflexes disappear?
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1 year - except startle - disappears at 3 months
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What is low birth weight classified as? What is it associated with?
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<2500 g. Associated with a greater incidence of physical and emotional problems. Caused by prematurity or intrauterine growth retardation. Complications include: respiratory distress syndrome, necrotizing enterocolitis, intraventricular hemorrhage, and persistent fetal circulation
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When is the rooting reflex apparent? what cognitive and social milestones happen at this time?
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birth to 3 mo
orients to voice |
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When does a baby hold its head up and the moro reflex disappears? What else happens at this time?
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3 mo
develops a social smile |
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When does a baby sit alone and crawl?
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7 - 9 mo
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When does stranger anxiety occur
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7-9 mo
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When do children walk, and babinski disappears? How much are they talking at this stage?
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15 mo
few words, separation anxiety |
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At what age can children climb stairs; stack 3 blocks, stack 6 blocks. What else?
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12-24 months
stacks 3 blocks at 12 months stacks 6 blocks at 24 months also: object permanence; 200 words and 2 word sentences at 2 |
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When do children develop core gender identity, and parallel play?
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24-36 months
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When can kids stack 9 blocks? What else happens then?
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30-36 mo
toilet training (pee at 3) |
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When can kids ride a tricycle; copies line or circle drawing? What else then?
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3 years
900 words and complete sentences |
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When can children draw stick figures, and hop on 1 foot? Cooperative play, imaginary friends, grooms self, brushes teeth, buttons and zips?
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4 years old
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What age do children get imaginary friends?
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4 yr old
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What happens during the senisorimotor stage of piaget's stages of cognitive development?
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birth to age 2 - egocentric exploration of the world with the 5 senses. Novel use of objects to obtain goal (eg. use of stick to reach something) Understanding of object permanence is achieved
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What happens during preoperational stage of Piaget's stages of cog. development?
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ages 2-7 - acquisition of motor skills. Magical thinking predominates with no "logical" thinking
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What happens durning concrete operational stage in piaget's stages of cog. development?
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ages 7-12 - start of logical thinking but confined to concrete concepts. No longer egocentric.
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What happens during formal operational stage of piaget's stages of cog. development?
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age 12+ - development of abstract reasoning
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What are the tanner stages of development?
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1) childhood
2) pubic hair appears (adrenarche); breasts enlarging 3) pubic hair darkens and becomes curly; penis size and length increase 4) penis width increase, darker scrotal skin, development of glands, raised areolae 5) adult; areolae are no longer raised |
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What are normal changes seen in the elderly?
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sexual change: men-slower erection/ejaculation, longer refractory period, women-vaginal shortening, thinning and dryness
-sleep patterns - decrease REM, slow wave sleep, increased latency and awakenings -common medical problems - arthritis, HTN, heart disease, osteoporosis -decreased incidence of psychiatric disorders -increased suicide rate (males 65-74 years of age have highest suicide rate in US) -decrease vision, hearing, immune response, bladder control - decreased renal, pulmonary, GI function - decrease muscle mass, increased fat sexual interest and intelligence does not decrease! |
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Grief what is it? How long does it usually last?
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normal bereavement characterized by shock, denial, guilt, and somatic symptoms. Typically lasts 6 mo - 1 yr. May experience illusions
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Pathologic grief
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includes excessive intense or prolonged grief or grief that is delayed, inhibited, or denied. may experience depressive symptoms, delusions and hallucinations.
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What are the kubler-ross stages of grief?
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denial, anger, bargaining, grief (depression), acceptance
stages do not necessarily occur in this order, and more than 1 stage can be present at 1 time |
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What are some effects stress can have on a body?
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production of free fatty acids, 17-OH corticosteroids (immunosuppression), lipids, cholesterol, catecholamines; affect water absorption, muscular tonicity, gastrocolic reflux, mucosal circulation
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What are things that can cause sexual dysfunction?
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1) drugs (antihypertensives, neuroleptics, SSRIs, ethanol)
2) diseases (depression, diabetes) 3) psychological (performance anxiety) |
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What is BMI?
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body mass index
BMI = kg/m^2 underweight <18.5 normal BMI 18.5 - 24.9 overweight 25-29.9 obese >30.0 morbidly obese >40.0 |
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Circadian rhythm. What drives it? what does it control?
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driven by suprachiasmatic nucleus (SCN) of the hypothalamus; controls ACTH, prolactin, melatonin, nocturnal NE release, SCN - NE release - pineal gland - mealtonin. SCN is regulated by environment (ex. light)
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Narcolepsy
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disordered regulation of sleep-wake cycles. may include hypnagogic (just before sleep) or hypnopompic (just before awakening) hallucinations. The patients nocturnal and narcoleptic sleep episodes start off with REM sleep
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Cataplexy
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loss of all muscle tone following strong emotional stimulus - in some patients. Strong genetic component
tx. stimulants (amphetamines, modafinil |
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what is the tx. for cataplexy?
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stimulants (amphetamines, modafinil)
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REM sleep
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increase and variable pulse, REM, increase and variable blood pressure, penile/clitoral tumescence. Occurs every 90 minutes ; duration increase through the night. Ach is the principal NT involved with REM sleep. REM decreases with age
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as the night goes on what happens to REM sleep?
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it increases in duration - but occurs every 90 minutes still
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What NT drives REM sleep?
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ACh
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What are the stages of sleep and the EEG wave form associated with them?
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-awake (eyes open), alert, active metal concentration - beta waves (highest frequency, lowest amplitude)
- awake (eyes closed) - alpha waves - stage 1 (5%) - light sleep - theta waves - stage 2 (45%) - deeper sleep, bruxism - sleep spindles and K complexes on EEG |
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what stage of sleep do people grind their teeth? how long do we spend in this stage of sleep?
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stage 2 - spend 45% of time in this stage - sleep spindles and K complexes on EEG
stage 3-4 (25%) - deepest, non-REM sleep; sleepwalking, night terrors, bed wetting (slow-wave sleep) - delta waves (lowest frequency, highest amplitude) - REM (25%) dreaming, loss of motor tone, possibly a memory processing function, erections, increase brain O2 use - beta waves 'at night BATS Drink Blood' - to remember the waveforms of the sleep stages |
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What is key to initiating sleep?
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serotonergic predominance of raphe nucleus
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What NT reduces REM sleep?
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NE
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What is responsible for extraocular movement during REM sleep?
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activity of paramedian ponteine reticular formation (PPRF)/conjugate gaze center
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paradoxical sleep and desynchronized sleep describes what sleep stage?
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REM sleep - because same waveform on EEG as when a person is awake (beta)
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What shorten stage 4 of sleep? What are they useful for?
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benzodiazepines - useful for night terrors and sleep walking
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What is used to treat enuresis? How does it work/
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Imipramine - shortens stage 4
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