important info from TBLs

Question 1

what is a biomarker? what is a key characteristics of a biomarker? give an example

Answer 1

• biomarker = biological characterisitc that is measured to indicate normal or pathogenic processes
• should be interpretable
• e.g. blood pressure

Question 2

define sensitivity

how do you calculate it?

Answer 2

• ability of a procedure to ditect a disease in each patient that possesses the disease
• to calculate: true positives/(true positives + false negatives

Question 3

define specificity

how do you calculate it?

Answer 3

• ability of a procedure to show that a patient does not have the disease in question
• to calculate: true negatives/(true negatives + false positives)

Question 4

define the positive predictive value (PPV)

how do you calculate it?

Answer 4

• value that conveys the probability that a patient who tests positive for a disease actually has that disease
• to calculate: true positives/(true positives + false positives)

Question 5

define the negative predicitve value (NPV)

how do you calculate it?

Answer 5

• values that conveys the probabilty that a patient who tests negative for a disease truly does not have the disease
• to calculate: true negatives/(true negatives + false negatives)

Question 6

define prevalence

how do you calculate it?

Answer 6

• total number of cases for a specific disease within a certain populaiton over a given time period
• to calculate: total number of positives (true and false)/total population

Question 7

what does a positive likelihood ratio (LR+) tell us about the association of a positive test result and having the disease?
how do you calculate it?

Answer 7

• as LR+ increases, there’s a stronger association btwn a positive test result and having the disease
• LR+ = sensitivity/(1-specificity)

Question 8

what does a negative likelihood ratio (LR-) tell us about the association of a negative test result and not having the disease?
how do you calculate it?

Answer 8

• as LR- approaches 0 there’s a stronger association btwn a negative test result and not having the disease
• LR- = (1-sensitivity)/specificity

Question 9

what is the difference between a prognostic and a predictive biomarker?

Answer 9

• prognostic biomarkers provide information about the likely outcome of a patient regardless of treatment
• predicitive biomarkers provide information about the likely effect of treatment

Question 10

what does prophylaxis mean in regards to treatment?

Answer 10

preventative treatment