Original Statistics and Epidemiology Flashcards
How does the WHO define the perinatal mortality rate?
The number of stillbirths and deaths in the first week of life per 1000 live births
How do MBRRACE define maternal MORTALITY?
The number of direct and indirect deaths per 100,000 pregnancies
How do MBRRACE define maternal DEATH?
A death that occured during pregnancy or within 42 days of the end of the pregnancy
What is standard deviation?
Square root of variance
What is variance?
Standard deviation squared
What is the definition of sensitivity?
The proportion of individuals with the disease that were correctly identified by the test
What is the definition of specificity?
The proportion of individuals without the disease who were correctly identified by the test
What is an accurate test used for measuring distribution?
Kolmogorov-Smirnov
What is a method of estimating distribution?
Histogram
What test is used to compare means between two separate groups of PARAMETRIC data?
Independant student t-test
What test is used to compare means between two separate groups of NON-PARAMETRIC data?
Mann-Whitney U
What test is used to compare results between two paired sample of PARAMETRIC data?
Paired student t-test
What test is used to compare results between two paired sample of NON-PARAMETRIC data?
Wilcoxon signed rank
What test is used to compare three or more measurements on one subject of PARAMETRIC data?
Repeated ANOVA
What test is used to compare three or more measurements on one subject of NON-PARAMETRIC data?
Friedman
What test is used to compare one variable between three or more separate variables of PARAMETRIC data?
One-way ANOVA
What test is used to compare one variable between three or more separate variables of NON-PARAMETRIC data?
Kruskal Wallis
What test is used to look for relationships between two continuous variables of PARAMETRIC data? (i.e. correlation)
Pearson coefficient
What test is used to look for relationships between two continuous variables of NON-PARAMETRIC data? (i.e. correlation)
Spearman coefficient
What is level of evidence IV?
Panel of experts - weakest form of evidence
What is level of evidence III?
Evidence from case, correlation, and comparative studies
What is level of evidence IIb?
Evidence from at least one well designed experimental trial
What is level of evidence IIa?
Evidence from at least one well designed controlled trial which is not randomized
What is level of evidence Ib?
Evidence from at least one Randomized Controlled Trial
What is level of evidence Ia?
Evidence from Meta-analysis of Randomized Controlled Trials
How is SEM (standard error of the mean) calculated?
SEM = SD/square root of sample size
How do you calculate 95% confidence intervals using SEM?
(mean - 1.96SEM) to (mean + 1.96SEM)
What is the incidence of ovarian cancer in the UK?
22/100,000
What is the maternal mortality rate for ectopic pregnancy in the UK?
2/1000 (0.2%)
What proportion of pregnancies are ectopic?
11/1000
What is the most common type of ectopic pregnancy?
Tubal - accounts for 93-95%
What is the risk of respiratory problems in VBAC compared to ELCS?
2-3% compared to 3-4%
What are the risks of VBAC?
1% additional risk of blood transfusion and endometritis
2-3/10,000 additional risk of birth-related perinatal death
22-74/10,000 risk of uterine rupture
8/10,000 develop HIE
What are the chances of success for a first VBAC?
72-76%
What are the chances of success of a 2nd VBAC, following a previously successful one?
87-90%
What factors reduce the likelihood of success of VBAC?
1) Induced labour
2) No prev. vaginal birth
3) BMI >30
4) If the C-section previously was for dystocia
What is the 5 year survival rate of stage I ovarian cancers?
90%
What is the 5 year survival rate of stage IV ovarian cancers?
17%
What is the most common cause of maternal mortality?
Cardiac disease (indirect)
What is the most common direct cause of maternal mortality?
VTE
What is the average age of diagnosis of endometrial cancer?
60
What is the absolute risk?
= the actual risk
What is relative risk?
= the ratio of risk comparing the risk in exposed vs. controlled groups
What are the risk factors for endometrial cancer?
1) PCOS
2) Obesity
3) Late menopause
4) Early menarche
5) HRT
6) Nulliparous
7) Diabetes
8) PD
9) Tamoxifen
How is sensitivity calculated?
A/(A+C)
How is specificity calculated?
D/(B+D)
How is negative predictive value (NPV) calculated?
D/(C+D)
How is positive predictive value (PPV) calculated?
A/(A+B)
What is the negative likelihood ratio?
(1-sensitivity)/specifity
What is the positive likelihood ratio?
sensitivity/(1-specifity)
What factor increases the risk of ovarian cancer?
Oestrogen-only HRT
What factors decrease the risk of ovarian cancer?
1) OCP
2) Increased parity
3) Breastfeeding
4) Hysterectomy
5) Tubal ligation
6) Statins
7) SLE
What is the most appropriate method to assess prognosis?
Cohort study
What is the miscarriage rate age 20-29?
10%
What is the miscarriage rate age 30-34?
15%
What is the miscarriage rate age 35-39?
25%
What is the miscarriage rate age 40-44?
50%
What is the miscarriage rate age >/=45?
90%
What do parametric tests assume?
Normal distribution
What type of tests are used when the population distribution is not known?
Non-parametric
What are the parametric tests?
Pearson; t-test; f-test; ANOVA; z-test
What are the non-parametric test?
Spearman; Mann-Whitney; Chi2; Wilcoxen signed rank; Fisher exact probability; Kruskal Wallis; Friedman
What are type I errors?
Incorrect rejection of a null hypothesis
False +ve
Detecting an effect that is not present
What are the type II errors?
Incorrect acceptance of a null hypothesis
False -ve
Failing to detect an effect that is present
What are ROC curves?
y = sensitivity
x = 1-specificty
What is the most appropriate method to assess diagnostic tests?
Cross-sectional studies
What is the most appropriate method to assess treatment/intervention?
RCT
How should the power of a study be described?
The study’s ability to detect an effect of a specified size?
Which condition is associated with a ‘greek helmet’ facial profile?
Wolf-Hirschhorn syndrome
What is the definition of incidence?
Number of new cases of a disease that occur in a population previously free of it
What is the definition of prevalence?
The frequency of existing disease at a given time
What are the parameters measured in APGAR scoring?
Pulse
Respiration
Muscle tone
Reflexes/irritability
Colour
How is cystometry performed?
Catheter placed in bladder with a pressure transducer to measure intravesical pressure
2nd catheter placed in either vagina or rectum to measure intra-abdominal pressure
How is detrusor pressure measured in cystometry?
Intravesical pressure - intra-abdominal pressure
What is a Kaplan-Meier plot used to graphically represent?
Probability of survival
What are case-control studies useful for?
Rare diseases
What are different types of categorical data?
Nominal/binary
Ordinal
What are different types of quantitive data?
Continuous
Discrete
What is mean sensitive to?
Outliers (extreme values)
The higher the power of a study, the lower the probability of what?
The higher the power of a study, the lower the probability of type II errors
High sensitivity is required for which sort of tests?
Screening tests, thus minimising missed cases
High specificity is required for which sort of tests?
Diagnostic tests, thus minimising misdiagnoses
