Numbers Flashcards
Define incidence
Number of new cases of a disease within a population
Define prevalence
Number of cases of a disease within a population at a single time
How do you calculate relative risk?
original
How do you calculate NNT (number needed to treat)?
1/ARR
What is the hierarchy of scientific evidence?
Systematic review RCT Cohort Case controlled Cross sectional Case report Mechanistic Editorial
What is a systematic review/meta analysis?
Where someone has analysed many studies in a single paper (meta analysis is a systematic review with statistical analysis)
What is an RCT?
Patients are randomised into either a treatment arm or a control arm and followed up over a period of time
What is a cohort study?
Patients are split into a treatment and control group and their outcomes can be paired but the grouping isn’t random
What is a case control study?
Where you have a set of patients with a disease and then look into their past for risk factors
What is a cross sectional study?
Where you take a snapshot of the population at a single point in time
What is positive predictive value?
The proportion of patients who test positive that actually have the disease
(true positive/tested positive)
What is negative predictive value?
The proportion of patients that test negative that don’t have the disease
(true negative/ tested negative)
What is sensitivity?
The proportion of patients who have the disease who test positive
(truly tested positive/true positive)
What is specificity?
The proportion of patients who don’t have the disease who test negative
(truly tested negative/true negative)
Define study population
All individuals we are interested in eg. all children with asthma in the UK
Define study sample
Group of individuals drawn from a population of interest that is studied to learn about the population
What is a 95% CI?
A range of values that you can be 95% certain contains the true mean of the population
Define p value
The probability you would get your result if the null hypothesis is true
What is standard deviation?
Describes variability within a particular sample
What is standard error?
A measure of variability of summary statistics between sample means
When is a CI statistically significant?
Difference between two means - exclude 0 is statistically significant
Ratio - exclude 1 is statistically significant
When is cost-utility analysis used?
Uses QALYs and incremental cost gained per QALY gained
When is cost-effective analysis used?
Outcomes are measured in natural units eg. pain score with incremental cost per life year gained
When is cost-benefit analysis used?
Outcomes are measured in monetary units to ascertain the net monetary benefit
When is cost-minimisation analysis used?
Measured in cost when outcomes have exactly the same outcome
What is the incremental cost effectiveness ratio?
Measure of monetary value against QALYs
= diff. in cost./diff. in benefits
