Rishi Desai, MD, MPH

Attributable risk (AR)

First Aid 

ATTRIBUTABLE RISK (AR) osms.it/attributable-risk ▪ AKA risk difference/excess risk ▪ Measures difference in disease risk between exposed population, unexposed population ▫ Often used in cohort studies  AR =  40 20 20 − = 0.4 − 0.2 = 100 100 100  AR × 100 incidence in exposed  AR for exposed individuals AR =  20 × 100 = 50% 40  A C − A+ B C + D  ▪ 50% of bladder cancer incidence → attributable to smoking in exposed population AR for population (PAR) PAR = incidence in population - incidence in unexposed PAR =  60 20 10 − = 0.3− 0.2 = 200 100 100  10 × 100 = 50% 20  MORTALITY RATES & CASE-FATALITY osms.it/mortality_rates_case-fatality ▪ Mortality rate: death incidence in population over period of time Annual mortality rate ▪ Mortality rate from all causes (crude death rate) ▫ Calculated by taking total number of  60  OSMOSIS.ORG  deaths from all causes in one year divided by total number of people at risk in population at mid-year ▪ Annual mortality = total number of deaths (850) ÷ total number of people at risk in population at mid-year (500,000) = 0.0017   

Introduction to biostatistics

Probability

Types of data

Chi-squared test

Fisher's exact test

Kaplan-Meier survival analysis

Kappa coefficient

Mann-Whitney U test

Spearman's rank correlation coefficient

Non-parametric tests

Type I and type II errors

Outcomes of statistical hypothesis testing

Correlation

Hypothesis testing: One-tailed and two-tailed tests

Linear regression

Logistic regression

Methods of regression analysis

One-way ANOVA

Paired t-test

Repeated measures ANOVA

Two-sample t-test

Two-way ANOVA

Parametric tests

Mean, median, and mode

Normal distribution and z-scores

Range, variance, and standard deviation

Standard error of the mean (Central limit theorem)

Statistical probability distributions

Biostatistics

Bias in interpreting results of clinical studies

Bias in performing clinical studies

Confounding

Disease causality

Information bias

Interaction

Selection bias

Causation, validity, and bias

DALY and QALY

Direct standardization

Incidence and prevalence

Indirect standardization

Mortality rates and case-fatality

Odds ratio

Relative and absolute risk

Epidemiological measurements

Positive and negative predictive value

Sensitivity and specificity

Test precision and accuracy

Evaluation of diagnostic tests

Disease surveillance

Modes of infectious disease transmission

Outbreak investigations

Prevention

Vaccination and herd immunity

Public health

Case-control study

Clinical trials

Cohort study

Cross sectional study

Ecologic study

Placebo effect and masking

Randomized control trial

Sample size

Study designs

Study design

Epidemiology

Attributable risk (AR)

Videos

Notes