stats/epidemiology Flashcards
incidence of ectopic pregnancy?
Mortality from ectopic pregnancy?
11/1000
Mortality = 2/1000
How many ectopic pregnancies are tubal ectopics?
What are the other types?
Which part of the tube are they in?
93-95%
Ampulla = 70%
Isthmus = 12%
Fimbrial = 5-11%
Interstitial = 3%
What are the positive and negative likelihood ratios?
+LR = sensitivity /(1-specificity)
-LR = (1-sensitivity)/specificity
These are used to determine how much a positive or negative test result changes the probability of a patient having a disease
+LR = how likely a disease is if the test is positive
-LR = how unlikely a disease is if the test is negative
What is a type 1 error?
What is a type 2 error?
Type 1 - false positive
- Incorrect rejection of a null hypothesis
- Detecting an effect that is not present
Type 2 - false negative
- Incorrect acceptance of null hypothesis
- Failing to detect an effect that is present
What are the levels of evidence?
1 is HIGH
4 is LOW
1a = meta-analysis of RCTs
1b = RCT
2a = non randomised CT
2b = well designed experimental trial
3 = some comparative study
4 = panel of experts
Most overall common cause of maternal death?
Direct vs indirect?
CARDIAC
Direct = VTE
Indirect = cardiac
What do cohort studies assess?
They group people by a risk factor and then can assess prognosis
What do case control studies assess?
They group people by outcome and then can look for riskfactors
How to interpret a ROC curve
Line closest to the top left corner is the most accurate test
What is absolute risk vs relative risk
Absolute = risk of a disease happening in the exposed group
Relative = risk of a disease in exposed group/unexposed group
How do you calculate odds ratio?
(disease present in exposed/disease not present in exposed) / (disease present in unexposed/disease not present in unexposed)
How does increasing sample size affect type 1 and 2 errors?
Decreases false negatives (type 2 errors)
What is the sample error of the mean? SEM
The standard deviation/square root of the sample size
It is the standard deviation of the sample means estimation of the population mean
How do you calculate confidence intervals?
(mean - 1.96xSEM) to (mean + 1.96xSEM)
What does the standard deviation measure
The varibility within the population
What does the standard error measure?
The variabiltiy between the sample means
What are the 5 year survival rates for stages of ovarian cancer:
1 - 90%
2 - 70%
3 - 40%
4 - 17%
Guess for the other stages in between this
Rates of resp problems in neonate born to:
VBAC
ELCS
VBAC - 2-3%
ELCS - 4-5%
Risks with VBAC:
- Uterine rupture
- Perinatal death
Rupture - 1:200
Periantal deathh - 2/3:10000
1% additional risk of need for transfusion
What is a cross sectional study the best for?
Assessing a diagnostic test
Which tests are for correlation? Parametric and nonparametric?
Spearman - nonparametric
Pearson - parametric
How does the WHO determine maternal mortality
number of deaths bet 100,000 LIVE births
Death during pregnancy or within 42 days of termination/delivery
What is the incidence of ovarian cancer?
How many women will have surgery for an ovarian mass in their lifetime?
22/100,000
Approx 10%!!!
What is the rate of miscarriage in women >45?
What about other ages?
Approx 93%
20-24 - 9%
25-30 - 11%
30-35 - 15%
35-39 - 25%
40-45 - 50%
>45 - 93%
Success rates for 1st VBAC
2nd VBAC
1st VBAC - 75%
2nd VBAC - 90%
What type of test can you use if you dont know the distribution of the population?
Non-parametric
What increases and decreases the risk of ovarian cancer?
Things that increase oestrogen cause an increased risk. Things that limit the number of ovulations cause an increased risk.
Increases:
- HRT (oestrogen only)
- Early menarchy and late menopause
- Nulliparity
- Family history and BRCA
- PCOS
- Obesity
- Endometriosis
Decreases:
- COCP - limits ovulations!
- High parity - limits ovulations!
- Breast feeding
- Hysterectomy/TL
What is the highest incidence rates and highest number of cases of ovarian cancer in the UK per age?
Incidence = >80
Number of cases 60-69
How does the WHO define perinatal mortality?
Number of deaths/1000 including stillbirths and death in first week of life
Commenses at 22 weeks gestation
Which tests require the data to be parametric aka have normal distribution?
ANOVA
f-test
t-test
z-test
pearsons
Like FACTS but FAPTZ
What are the axis of a ROC curve?
Sensitivity vs 1-specificity
Kind of like positive likelihood ratio
What is the average age of diagnosis for endometrial cancer?
What is the highest incidence age group?
Average age diagnosis = 60
Highest incidence group 70-74
