1
Q
What is a cross sectional study?
A
- Purely observational
- Asks, what is going on at this point in time
- Snap shot of exposures and outcomes simultaneously
- Shows risk association with disease
DOES NOT ESTABLISH CAUSALITY
*Disease prevalence is characteristic measure
2
Q
What CAN’T a cross sectional study establish?
A
Causality
3
Q
What is disease prevalence characteristic measure of?
A
Cross sectional study
4
Q
What is prevalence?
A
Portion of people in population with disease at any given time
5
Q
Weakness of cross sectional study?
A
Shows correlation, but DOES NOT prove causation
*For example, maybe there is another factor that is causing both the disease and the risk factor you are studying
6
Q
What is a case control study?
A
Observation and RETROSPECTIVE study asking, "what happened?" Case: subjects with disease Control: subjects without disease - Previous exposure is being analyzed *Metric is the odds ratio
7
Q
What is the odds ratio the metric in?
A
Case control study
8
Q
What is odds ratio?
A
- Odds of exposure to risk factor in case (disease) : odds in control (healthy)
- **Does exposure increase odds you have disease
- Used in case control study measuring:
- ***If odds ratio is 9, you’re 9 times more likely to develop disease if you had exposure
9
Q
Define odds?
A
Odds = P / (1 - P)
- P = probability event happening
- 1 - P = probability not happening
10
Q
What is a cohort study?
A
Observational prospective study
“Does exposure increase risk of disease?”
- If high cholesterol, will you have higher risk of MI
*Relative risk is characteristic measure
- Focusing on if risk is causing disease
11
Q
What study uses related risk?
A
Cohort study
12
Q
What is relative risk?
A
P1/P2
P1 = risk of disease if exposed
P2 = risk of disease is unexposed
13
Q
What makes a clinical trial high quality?
A
- Randomization
- Controlled
- At least double blind
14
Q
What is single, double, triple single?
A
Single: patient doesn’t know if getting treatment
Double: Neither doctor or patient know who got drug
Triple: same as above but researcher also does not know
15
Q
What is phase 1 study?
A
- Drug studied in 10 - 20 healthy volunteers
- Assess safety, toxicity, kinetics
16
Q
What is phase 2 study?
A
- 100s of people WITH disease to assess efficacy
17
Q
What is phase III study?
A
- 1000s of people with disease
- Treatment assessed vs. placebo or best available treatment
18
Q
Trick to remember # of people in phases of study?
A
The number of the phase, corresponds to number of zeros in patients studied
19
Q
What is phase IV?
A
- All people on drug post release to assess rare or LT effects
20
Q
Questions being asked in 4 phases?
A
- Is it safe
- Does it work
- Is it more effective
- Can we keep on using it
21
Q
When drawing 4x4 box what is on left side and top of it?
A
Left: test
Top: disease
***Just read it left to right, “we are testing for disease”
Test comes before disease as it does on chart
22
Q
Define sensitivity?
A
Ability to detect disease when it is actually present
23
Q
Equation for sensitivity?
A
TP / (TP + FN)
24
Q
What are high sensitivity tests good for?
A
"SNOUT" SN = sensitivity Out = ruling out Ruling things out ***This is true because high value is approaching one with means false negative = zero
25
Define specificity?
- Ability to indicate non disease when disease is not present
26
Equation for specificity?
TN / (TN + FP)
27
What are tests with high specificity good for?
"SPin"
SP = Specificity
IN = Ruling in a disease
*As value approaches 1 it will have very few false positives
*Good for confirmatory test after positive screening
28
Equation for positive predictive value?
TP / (TP + FP )
29
Equation for negative predictive value?
TN ( TN + FN )
30
Which values vary with prevalence of disease?
PPV and NPV
| *Sensitivity / specificity DO NOT
31
Impact of high prevalence of disease on measurements?
Higher PPV, lower NPV
32
Difference between prevalence and incidence?
Prevalence includes old cases where incidence does not
33
How does the 4 x 4 chart switch when using it for odd ratio?
Exposure is on left, disease is on top:
- Makes sense in reading left to right as you must first be exposed to get the disease
* *Then layer in A, B, C, D alphabetically as if you were reading
34
What is the odds ratio equation?
( A*D ) / ( B*C )
35
Does odds ratio imply causation?
No, only correlation
| - Remember there could be another factor causing both the risk factor and the disease
36
Relative risk equation?
( A / [A + B] ) / ( C / [C+D] )
37
Relative risk reduction equation?
1 - RR
38
What is attributable risk?
Difference in risk between exposed and unexposed group?
39
Attributable risk equation?
(A/ [A+ B] ) - ( C / {C+D} )
40
What is absolute risk reduction?
Difference in risk attributable to intervention
41
Equation for absolute risk reduction?
( C / {C+D} ) - (A/ [A+ B] )
42
What is number needed to treat?
Number of patients needed to be treated for 1 patient to benefit
43
Equation for number needed to treat?
1 / ARR (Absolute risk reduction)
44
What is number needed to harm?
Number of patients needed to be exposed to risk factor for 1 patient to be harmed?
45
Equation for number needed to harm?
1 / AR
| - Think AR = AR assault rifle
46
What is precision?
Consistency and reproducibility of a test
| ***AKA reliability
47
Another name for reliability of test?
Precision
48
What is accuracy? Another name for accuracy?
How close test measures are to true values
| - AKA: validity
49
Another name for validity?
Accuracy
50
What does random error do?
Decreases precision and reproducibility of test
51
What is systematic error?
Reduces accuracy by consistently skewing results in a particular direction
52
What is bias?
1 result / outcome is systematically favored over another
53
What is berkson's bias?
Only people from hospital were selected for study: form of selection bias as they are not as healthy as the general population
- Same idea occuring if you select people healthier than normal
54
What type of bias is it if certain type of people drop out of study?
Selection
55
What is procedure bias?
Subjects in different groups are not treated the same
56
What is lead time bias?
Detecting disease early being confused with better survival
57
What is the median?
Middle number in set when organized numerically
58
Measurement most affected by outliers? Least?
Most: Mean
Least: Mode
59
How is median calculated with even list of numbers?
Average of middle two numbers
60
What happens to SD in very precise test?
It is decreased
61
%s falling in first 3 standard deviations?
1st: 68
2nd: 95
3rd: 99.7
62
Equation for standard error of mean?
Standard deviation / (Square root sample size)
| * As sample size increase, SEM decreases
63
Does standard deviation impact sample size?
No, only impact standard error of mean
64
Break out of measurements in positive /negative skewed distribution?
Positive: Mode Median > Mean
65
Best number in skewed distribution?
Median
66
What is the null hypothesis?
That there is no statistical difference between 2 groups
67
What is on 4 x 4 box in hypothesis testing?
Results on left, population on top
68
What is type I error?
Stating there is an effect/difference when one does not actually exist
- Null rejected, experimental accidently accepted
- This is in box B
69
What is alpha?
The probability of making type I error (Study says there is a difference when in reality there is not)
70
How to interpret P value?
If P
71
What is type II error?
"Box C"
- Saying there is not a difference when there really is one
- You fail to reject null hypothesis when in reality it is false
72
What is beta?
Probability of making type II error
73
Ways to reduce Type II error?
1. Increase sample size
74
2 things decreased by increasing sample size?
1. Type 2 error
| 2. Standard error of mean
75
Which error is false negative / positive?
Type I: False positive
| Type II: False negative
76
What is power?
Likelihood you find a difference when one truly exists
| - Probability of rejecting null hypothesis when it is false
77
What is a powerful study?
High likelihood of finding a difference if one is present
78
Equation for power?
1 - Beta (this is type II error )
79
What impacts power?
1. Samples size increases: power in numbers
2. Decreased standard deviation
3. Increased alpha
4. Increased mean value between groups
80
What is confidence interval?
Range of values in which specified sample means is expected to fall
81
What does 95% confidence interval correspond to?
P value of .05
82
What is Z score at 95% / 99%confidence interval?
95%: 1.96
| 99%: 2.58
83
3 rules for interpreting confidence intervals?
1. If 95% confidence interval for mean difference between 2 variables includes zero, then there is no significant difference and should not reject null hypothesis
2. If 95% interval for odds ratio or relative risk includes 1, null hypothesis should not be rejected
3. If CI between 2 groups overlap, they are note significantly different
84
What does a T test do?
Compares mean of 2 groups to see if there is statistical difference
85
What is Anova test?
- Compares means of > 3 groups to see if statistical difference
* Same as T, just for more groups
86
What is Chi square test?
- Comares 2 or more percentages or proportions of categorical outcomes
- EG: comparing % of smokers with lung cancer to % smokers without lung cancer
87
What is correlation coefficient?
- 1
88
What is coefficient of determination?
R Squared
89
What is autonomy?
Respect patient as individuals and honor their preferences in medical care or refusing care
90
What can refuse treatment?
Any competent person > 18 at any time
91
Does autonomy or beneficence trump?
Autonomy
92
3 conditions of informed consent?
1. Disclosure: discussion with patient
2. Capacity and understanding to agree to plan
3. Acting voluntarily / free from coercion
93
Exceptions to informed consent?
1. Patient lacks capacity: act in beneficence
2. Medical emergency: implied consent
3. Therapeutic privilege: withholding info if it would damage outcome
- EG: not telling suicidal patient they have cancer
94
How can minor be emancipated?
1. Married
2. Have a child
3. Self supporting
4. Joined military
95
When is parental consent not required?
1. Emergency care
2. Contraceptives
3. STDs
4. Management of addiction
96
When is parent not allowed to refuse treatment for child?
Life and death situation
97
Components of decision making capacity?
1. Make and communicate choice
2. Fully informed
3. Stable decision over time
4. Consistency with their values and goals
5. No delusions or hallucinations
6. > 18 yo or emancipated
98
Do intoxicated people have capacity?
No
99
What is a living will?
Written description of treatments if patient becomes incapacitated
100
What is the order of surrogate decision making?
1. Spouse
2. Adult children
3. Parents
4. Siblings
101
When is confidentiality waived?
1. Harm to self / others
2. No way to warn / protect people at risk
3.
102
When should you go to superior, court, or ethics committee?
This is almost never the answer
103
When should you refer patient to another physician?
never
104
What to do in non adherence?
Find out why and determine willingness to change behavior
105
What to do if patient continues to smoke?
Ask how they feel about smoking then offer advice if they express desire to quit
106
Response if trouble taking medicines?
- Give written instruction and try to simplify regimen
107
What to do if family asks for information?
Avoid this unless explicit permission is given from patient
108
What to do if child wants to know about illness?
Ask parents first what they have told child
109
What to do if pregnant minor?
1. DO NOT advise abortion
2. Advise to talk to parents
3. Mother retains right to make decisions about fetus
110
What to if family wants adoption on child wants to keep baby?
- Provide her with information about caring for child
| - Encourage open dialogue with parents
111
What to do if patient asks for suicide??
Refuse involvement and give appropriate analgesic
| - Medically appropriate analgesics can be given even if it will shorten life
112
What to do if suicidal?
Suggest they remain in hospital voluntarily
113
When can suicidal person be withheld in hospital against will?
- They refuse to be admitted
| - You deem them to lack capacity
114
If patient gets romantic?
1. Never
2. Ask for chaperone
3. Don't say not while they're a patient
4. Ask direct, close ended questions
115
What to do if patient says they feel ugly?
1. Ask why they feel this way
| 2. Do not provide reassurance
116
What to do with angry patient?
1. Acknowledge anger without taking personally
2. Do not make excuses
3. Encourage open communication with old physicians
4. Apologize but dont try to explain it
117
What if patient is upset about how other doctor treated them?
Encourage them to speak directly with doctor
118
What if patient has problem with office staff?
Tell patient you will speak to that person personally
119
What to do if medical error is made?
Always inform patient
120
When does moro disappear?
3 months
121
When does rooting disappear?
4 months
122
When does palmar disappear?
6 months
123
When does babinski disappear?
12 months
124
When can baby lift head?
1 month
125
When can baby roll and sit?
6 months
126
When can you crawl?
8 months
127
When can you pincer?
10 months = 10 fingers for ten hands
128
When can you stand?
10 months = on all 10 toes
129
When can you walk?
12 - 18 months
130
When can you smile?
2 months
131
Stranger and separation anxiety?
Stranger: 6 months
Separation: 9 months
132
Orient to voice / name?
Voice: 4 months
Name: 9 months
133
Object permanence?
9 months
134
Mama and dada?
10 months
135
When can you say single words?
1 year
136
Parallel play?
12 months
137
Rapprochement?
24 months
138
Cooperative play?
36 months
139
Core gender identity?
36 months
140
Imaginary friends?
48 months
141
Kick a ball?
24 months
142
200 word vocab / 2 word phrases?
24 months
143
Tricycle?
3 years
144
1000 word vocab?
3 years: think, 1 year for each zero
145
Detailed stories?
48 months
146
How many cubes can a kid stack?
Age in years x 3
147
When can you complete simple shape?
3 years
148
Does sexual interest decline in age?
Not in men: decreased libido in women post menopause
149
Sleep changes in aging?
1. Decrease REM
2. Decrease slow wave
3. Increased awakening
4. Increased latency
150
Age group with highest suicide rate?
65 - 74
151
Fat change in old age?
Brown: decreases
White: increases
152
3 stages of disease prevention?
Prevent
Screen
Treat
153
What to say if stem says "offer them specific drug because they have medicaid?"
Dont do it! Offer them best and all treatment options regardless of insurance
154
What gets medicare?
1. > 65
| 2.
155
4 parts of medicare
Part A: Admissions to hospital
Part B: Basic bills
Part C: Combined (A + B by private company)
Part D: Drugs
156
What is medicaid?
Insurance for Destitute
157
When can you point?
12 months
158
Climb stairs?
18 months
159
Feed self with fork?
20 months
160
When can you copy line, circle, etc?
4 years
161
Hop on one foot?
4 years
162
Use button / zipper?
5 years
163
Greatest killers
1. Congenital defects
| 2.
164
Greatest killers > 65?
1. Heart disease
| 2. Cancer
165
Age group with greatest cancer death?
45 - 60 yo
166
Who is cancer second leading cause of death for?
1 - 14
35 - 44
> 65
167
Greatest killer across all groups?
Unintentional injury
168
When does hospital visit count as readmission?
Within 30 days of first visit and does not have to be for readmission
169
What is human factors design?
Limiting human error by developing systems that simplify and standardize protocol
170
What is the PDSA cycle?
Plan
Do
Study / analyze
Act
171
Example of balancing measurement?
How do HBA1C levels correlate with disease
172
Example of process measurement?
Performance of system: % of patients with HBA1C measurement in 6 months
USMLE: step 1
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