1. Objectives of epidemiology a. Underst& the aetiology or cause of a disease (risk factors) b. Find out the extent that a disease or health problem affects a community or population c. Determine the natural history or prognosis d. Evaluate existing & newly developed preventative therapeutic measures & modes of healthcare delivery 2. Define, compare, calculate, & interpret Measures of Morbidity a. Incidence rate: measurement of the number of new individuals who contract a disease during a particular period of time i. Calculation: Number of new cases of disease or injury during specified period DIVIDED BY Size of population at start of period b. Attack rate: Same as risk, proportion of individualsin a population (initially free of disease) who develop the disease within a specified time interval. i. Calculation: Total number of new cases DIVIDED BY The total population c. Prevalence: measurement of all individuals affected by the disease at a particular time i. Calculation: Number of new cases of disease or injury during specified period DIVIDED BY Time each person was observed, totaled for all persons d. These rates are used to measure disease occurrence & make comparisons between population groups. They are commonly used measuresthat help our underst&ing of the distribution of disease in a given population. 3. Underst& why incidence data are important for measuring risk. a. Incidence is important for measuring risk because it tells you the rate at which new people are contracting the disease 4. Define, compare, calculate, & interpret Measures of Mortality a. Mortality: a measure of the frequency of occurrence of death in a defined population during a specified interval. Morbidity & mortality measures are often the same mathematically; it's just a matter of what you choose to measure, illness or death. i. Calculation: Deaths occurring during a given time period DIVIDED BY Size of the population among which the deaths occurred TIMES 10n b. Cause-specific mortality rate: The mortality rate from a specified cause for a population. i. Calculation: The number of deaths attributed to a specific cause DIVIDED