Practice Questions 4 Flashcards
1
Q
What is lifetime prevalence?
A
Proportion of individuals in population who have ever manifested a disorder who are alive on a given day.
2
Q
What is lifetime morbid risk?
A
Probability of a person developing a disorder using entire period their life
3
Q
Which lifetime calculation includes those deceased?
A
Lifetime morbid risk
4
Q
For which type of disorders does age-specific incidence rates give approximate lifetime morbird risk?
A
Low incidence disorders
5
Q
Calculation for attack rate
A
Number of cases that develop/number exposed in a cohort (at risk)
i.e. incidence rate following acute exposure
6
Q
Who created the filter model/pathways of care
A
Goldberg
7
Q
What is the infant mortality rate?
A
Deaths under 1 year of age
8
Q
What type of bias does blinding reduce?
A
Measurement
9
Q
What is a factorial RCT?
A
When 2 or more interventions are compared separetly but also in combination and against a control
10
Q
How are screening tools usually evaluated?
A
Cross-section studies
11
Q
Describe Guttman scalogram
A
If you agree to one statement you agree to all statements beneath it. Also known as cumulative scaling.
12
Q
What is Guttmann scalogram useful for?
A
Hierarchical constructs e.g. political views
13
Q
Describe positive skew
A
mean>median>mode
14
Q
unit of coefficient of variation
A
%
15
Q
Define coefficient of variation
A
the sample standard deviation divided by the sample mean of the data set
16
Q
Where are the mean and mode in skewed distributions?
A
Mode are always on the shorter side
Mean are always on the longer side
17
Q
Calculation for probability of one of two events occurring which are mutually exclusive
A
the sum of their probabilities, minus the probability that both will occur
18
Q
What is multistage sampling?
A
2x sampling events.
Initially, the larger primary units are randomly selected (e.g. municipalities in a country). Later individual units (households) within primary units are randomly selected for measurement
19
Q
What is disproportionate stratified random sampling?
A
If a subgroup of interest is extremely small, we may also use different sampling fractions (f) within the different strata to randomly over-sample the small group.
Within each stratum, all individuals have an equal chance of being selected for the study.
20
Q
What is the target population?
A
The group to which we wish to generalize the results of a study.
21
Q
What type of error can be caused by repeating test on the same set of data?
A
Type 1
22
Q
Value of no difference for NNT?
A
Infinity
23
Q
What is a necessary condition for Validity?
A
Reliability
24
Q
Values of Cronbach’s alpha
A
-infinity to +1
25
What does Cronbach's alpha measure?
Internal consistency
26
When is multiple regression used?
when we have one dependent (Y) variable and many independent (X) variables.
27
Purpose of multiple regression?
to find an equation that best predicts the Y variable as a linear function of the X variables.
28
What type of test is multiple regression?
Multivariate
| Requires parametric data
29
What is a prerequisite for regression?
Correlation
30
What value of kappa implies perfect disagreement?
-1
31
What is kappa a measurement of?
Agreement
32
Degrees of freedom for chi square?
(number of rows-1) X (number of columns-1)
33
What does multivariate mean?
Multiple independent variables
34
IV and DV in logistic regression?
DV: categorical
IV: categorical, continuous or discrete
35
What tests can be used for paired data?
Wilcoxon rank sum
Sign
Paired t test
36
What is Wilcoxin used for?
Non-normal data from large samples
37
What does degrees of freedom mean?
The extent to which a set of observations are 'free' to vary
38
What test is used to compare two survival curves?
Log rank test
39
What does Cochrans criteria refer to?
Criteria that must be fulfilled if the chi-square test is to be used for testing statistical significance
40
What are Cochrans criteria?
1. All expected values in each cell have a frequency count = 1 i.e. non-zero values
2 At least 80% of total cells must have expected value of = 5
41
For which data type ca we use weighted kappa?
Ordinal
42
Assumptions for using ANOVA?
1. Parametric distribution
2. Equal variance amongst tested groups
3. Independent observations
43
IV and DV for ANOVA
IV: categorical
DV: continuous
44
IV and DV for one-way ANOVA
IV: categorical
DV: continuous
45
What must be normally distributed for regression to be used?
DV
46
Calculation for Kappa
Kappa = Observed agreement beyond chance / Potential agreement beyond chance
47
What is the coefficient of determination (R^2)?
the proportion of the total variation in the dependent variable that is accounted for by the regression model (independent variable)
48
What does R^2 close to 1 imply?
that most of the variability in the dependent variable is explained by the regression model built using the predictors.
49
What is repeated measures ANOVA used for?
to compare paired observations within subjects across multiple groups.
50
What is the chi square equivalent for non-parametric data?
McNemars
51
What is the chi square equivalent for paired data?
McNemars
52
What is the type of sampling where every nth member is picked?
Systematic (non-random)
53
What is the name of the graph that is used to identify potential heterogeneity in which effect size is plotted against a measure of precision??
Galbraith plot
54
Level of non-significant difference for mean?
0
55
What is the normally accepted type 1 error rate?
5% (0.05 aka p value)
56
What is the square root of the variance?
SD
57
Which parametric test is used to compare 3 or more groups?
One-way ANOVA
58
IV and DV of logistic regression
DV: binary
IV: one or more
59
IV and DV for multiple linear regression?
1 DV
| 2 or more IV
60
What does multiple linear regression suggest?
Several IV together predict single DV
61
What is logistic regression used to predict?
Relationships between binary DV and several IV
62
When is logistic regression used?
If DV is binary
63
Calculation for population attributable risk
It is calculated by multiplying the attributable risk by the prevalence of exposure to the risk factor, and can be expressed by the formula PAR = Attributable risk X Proportion of population exposed.
64
What is attributable risk?
Attributable risk is the difference in risk between the exposed and the non-exposed.
65
Calculation for population attributable fraction?
PAF = Pe(RR - 1)/(1 + (Pe(RR - 1))), where Pe is the proportion of the population exposed to the factor and RR is the unadjusted relative risk of the outcome
66
What is the attributable risk?
Risk value attributable to exposure is the attributable risk.
67
How does one calculate the attributable risk?
. It is derived from obtaining the difference between control and experimental event rate.
68
Calculation for PAR?
It is derived from multiplying ARR from a study data with the proportion of a population that is exposed.
PAR = ARR X proportion of population exposed.
69
In which type of study is OR used?
Case control
70
What is incidence density sampling?
It involves matching each case to a set of individuals (usually >1) that are at risk of the exposure at the time of case occurrence.
71
What is needed in a study if the prevalence of a condition is low?
Larger sample size
72
What happens to sensitivity and specificity when two tests are used in sequence?
Loss in sensitivity
| Gain in specificity
73
What happens to sensitivity and specificity if two tests are used in tandem?
Gain in sensitivity
| Loss of specificity
74
What leads to high false positives?
Low-cut off
75
What happens if there is a high cut off for a disease?
Increased sensitivity
Decreased specificity
More false positives
76
What two things affect the predictive value?
Prevalence
| If disease is rare - specificity
77
When do you want to avoid false negatives?
Deadly disease that has curative treatment i.e. can be treated early
78
Calculation for post-test odds?
LR x pre-test odds
79
What does 1-specificity refer to?
False positive rate
80
Y axis of Kaplan-Meier curve?
Proportion of those who have not achieved the outcome of interest
81
What is the hazard function?
the conditional probability of dying at time t having survived to that time.
82
What can log rank test allow us to do?
Assess influence of categorical variable on survival
83
What to use if we want to assess influence of continuous variable on survival?
Hazards/cox regression
84
What tests are used for survival?
Cox regression
| Log-rank (categorical data)
85
What is the 'hazard' in Kaplan Meier curves/cox regression?
DV
86
What is power?
Ability to detect true difference if it exists
87
What affects power?
Sample size
Effect size being tested
Variability (SD)
88
What is a surrogate outcome?
Any outcome that is easily measurable but used as a proxy for the actual primary outcome of direct benefit to patients.
89
What is a composite endpoint?
Composite end points (CEPs) capture the number of patients experiencing any one of several adverse events— e.g. death, MI, or hospitalization—as a primary study endpoint.
90
Reason to use composite endpoint?
to decrease the necessary sample size and duration of follow-up.
Uncertainty about single best outcome measure.
91
Calculation for RRR
1 - (EER/CER)
92
Unit of RRR
%
93
What does RRR describe?
Reduction in events as a %
94
What does ARR describe?
Reduction in people affected by the event i.e. size of the effect
95
What happens to power if cluster sampling is used?
It is reduced
96
What is used instead of sample size in cluster sampling?
Effective sample size
97
What is used to calculate effective sample size?
Variance inflation factor/design effect derived from intracluster coefficient
98
What is intracluster correlation?
Proportion of total variability of outcome measure attributed to between-cluster variability
99
What does high intracluster correlation suggest?
All of the variability is due to between-cluster differences and responses within a cluster are highly correlated.
100
How would you calculate CI using ARR?
Higher limit NNT = 1/lower limit of ARR
Lower limit of NNT = 1/higher limit of ARR
101
Another name for a forest plot?
Blobbogram
102
Name a measure of effect size
Cohens d
103
What can be used to detect publication bias?
Funnel plot
Failsafe N
Galbraith plot
Comparing published vs unpublished data
104
Calculation for accuracy
Add the two sets of true observations - true positive and true negative then divide by total sample size
105
Define accuracy
The proportion of the sample that was correctly classified using the screening test.
106
Calculation of attributable risk proportion
Incidence/incidence in exposed or
AR/EER
107
Calculation for PAR
attributable risk x prevalence of exposure in the population
108
Calculation for attributable risk percentage
AR/EER x 100
109
Which study design is best for rare diseases?
Case-control
110
Which study design can be used to study multiple risk factors?
Case-control
111
In which type of study can incidence be calculated?
Cohort
112
Difference between confounder and effect modifier?
a confounder distorts the relationship and produces an incorrect result.
effect modifier is a third factor that affects the magnitude of the cause-effect relationship.
113
If crude risk differs from adjusted risk, what can one conclude?
the stratified factor is a confounder.
114
If the relative risk of one stratum is different from other strata (subgroups) what can one conclude?
then we can call the factor an effect modifier.
115
Difference between cost minimisation and cost benefits?
Cost minimisation: both scales looking at same outcome so both can be changed to monetary values
Cost benefit: between two outcomes with different scales which are represented in monetary terms
116
In which economic analysis are the outcomes assumed to be equal and therefore only comparative cost is assessed?
Cost minimisation
117
Does the denominator for incidence rate include those who already have the illness?
No
118
What is the attack rate?
number of cases that develop divided by number exposed in a cohort (at risk). It is simply an incidence rate following an acute exposure.
119
What type of bias does blinding aim to reduce?
Measurement bias
120
What is it called when 2+ raters are used to analyse the data of Qualitative studies?
Triangulation
121
What is sequential RCT?
the participants are recruited into each group until the investigators can clearly determine the difference or lack of difference between the groups. The sample size is not fixed a priori, and the analysis is regularly done , and the trial is stopped by a stopping rule, leading to a lower cost associated with the trial.
122
What is intensity sampling?
Specifically picking a subject who is an expert in the topic
123
What type of brain damage leads to working memory deficits?
Damage to genu of corpus callosum
124
Risk fo Downs in someone who is 35 (mother)
1/350
125
Risk of Downs in a 25 year old mother
1/1200
126
Risk of Downs if mother is 40
1/100
127
Risk of Downs if mother is 49
1/10
128
Which therapy uses hypothetical and circumscribed questions?
Psychodynamic
129
Difference between Tourettes and Chronic tic disorder?
In chronic tic disorder you have either motor OR vocal tics - not both
130
Which MH problem is most common in Autism?
Social Anxiety
131
1st line medication for ADHD in adults
Methylphenidate
132
Which depot requires monitoring for 2 hours post-injection?
Olanzapine
133
Early signs of opiate withdrawal?
agitation, anxiety, muscle aches, increased tearing, insomnia, runny nose, sweating, yawning.
134
Late sx of opiate withdrawl?
abdominal cramping, diarrhoea, dilated pupils, goose bumps, nausea, vomiting.
135
Which cognitive deficits are most often found in those with schizophrenia?
Working memory
136
Which antipsychotic (2nd gen) can cause dysphagia in those with LD?
Olanzapine
137
Best benzo to treat DT if cirrhosis?
Lorazepam
138
Difference between methadone and buphrenorphine
Methadone doesnt have a ceiling effect, buprenorphine does
| Methadone is best for patients dependent on high doses of opioids
139
Most common parkinsonian sx secondary to antipsychotics?
Clasp knife rigidity
Rigidity
Bradykinesia
140
Which family therapy gives homework assignments?
Strategic
141
Which rec drug can cause UC?
Ketamine
142
What medications can cause false positive for amphetamines?
```
Amantadine
Penicillin
Bupropion
Ephedrine
Phenothiazines
Ranitidine
Selegiline
Trazodone
Methylphenidate
Phenylphrine
```
143
What drug causes false positive for benzos?
Sertraline
144
What drugs cause false positive for Cannabis?
NSAIDs
| PPIs
145
What drug causes false positivies for cocaine?
Topical anaesthetics
146
What drugs cause false positives for opioids?
Codeine & preparations e.g. cough mixture
Tonic water
Poppy seeds
Verapamil
147
Prevalence of dystonia
10%
148
Prevalence of pseudo-parkinsonism
20%
149
Prevalence of akathisia
25%
150
Prevalence of tardive dyskinesia
5%
151
First chocie options for refractory depression
```
Add Lithium
Add T3
ECT
Combined use of olanzapine and fluoxetine
Add quetiapine to SSRI/SNRI
Add risperidone
Add aripiprazole
Bupropion & SSRI
SSRI & Venlafaxine/Mirtazapine/Mianserin
```
152
Average suicide rate for the England
1 in 10,000
153
Average suicide rate for mental health service users in England
1 in 1000
154
Which medication is licensed for ADHD in adults?
Atomoxetine only
155
Incidence of puerpural psychosis?
1 in 500
156
Calculation for RRR?
RR-1
157
Calculation for ARR?
PEER (patient expected event rate) or CER x RRR
158
What is the non-parametric equivalent of ANOVA?
Kurskal-Wallis
159
What is the non-parametric equivalent of repeated measures ANOVA?
Friedman test
160
Which test compares two different interventions with two different clinical outcomes in terms of money?
Cost benefit
161
What reliability is a measure of internal consistency of a test?
Split half reliability
162
Define SEM
Dispersion of sample mean aorund true mean
163
Risks to babies of mothers on Lithium during pregnancy
```
Ebsteins Anomaly
ASD
VSD
Neonatal goiter
Hypotonia
Lethargy
Cardiac arrhythmias
```
164
Risk of septal heart defects in babies of mothers on citalopram?
2-2.5 fold increase
165
Risk of PPH in babies of mothers on citalopram?
6 times greater
166
Which ethnicity lacks one copy of functional CYP2D6?
East Asians
167
Which disorders have low cortisol?
CFS
PTSD
Fibromyalgia
168
Which meds increase lamotrigine levels?
Valproate
169
Which meds decrease lamotrigine levels?
Oral contraceptives
| Carbamazepine
170
Which antipsychotic can cause myoclonic seizures?
Olanzapine
171
Which age suggests good prognosis of anorexia?
Younger age
172
1st line medication for kids with OCD
Sertraline
173
How many children with depression later manifest bipolar?
20%
174
How many <65 have FTD?
12%
175
Which heroin replacement therapy is recommended for women breast-feeding?
Methadone
176
During what time following cessation of alcohol is risk of seizure highest?
First 24 hours
177
Prevalence of depression among patients with alcohol dependence?
25-30%
178
What % of men in the UK drink above weekly limit?
26%
179
What % of women in the UK drink above the weekly limit?
15%
180
Prevalence of hazardous drinking in men
38%
181
Prevalence of hazardous drinking in women
15%
182
Which age group in women have highest level of drinking?
16-19 (32%)
183
Which age group in men have highest level of drinking?
20-24 (62%)
184
How is total alcohol consumption expressed?
By per capita consumption figures for people >15 years
| It is the average amount of pure alcohol in litres consumed in 1 year
185
How many adults in the UK smoke cannabis?
10%
186
How many cannabis users are <24?
50%
187
How many school children have used cannabis in the last year?
12%
188
What is proportionate mortality rate?
Ratio between deaths due to specific cause and total deaths in population
189
What is case fatality rate?
Number of deaths due to a disease and number of people affected by a disease
190
What does I^2 value tell us?
% of variability in effect estimates that is due to heterogeneity
