Epidemiology Quiz 2

standardized mortality ratio (SMR) using indirect age adjustment

-when numbers of deaths for each age-specific stratum are not available (but total count is available) -Study mortality in an occupationally exposed population

Crude vs. Adjusted rates

Crude rates - Because the age, gender, etc. distribution of individuals within a population may differ, a direct comparison of crude rates across populations may result in incorrect conclusions. Adjusted rates - AR are used to adjust for some of these potential biases.

Crude Death Rate

Deaths occuring during a given time period/Size of population which deaths occured Crude death rate refers to the number of deaths occurring throughout a year, per 1000 population of a country

interpretation of SMR

SMR = 1 : the health-related states or events observed were the same as expected from the standard population (no difference in risk) SMR > 1 : more health-related states or events were observed than expected from the standard population. (population you're interested in has a higher risk than standard population --> worse health) SMR < 1 : less health-related states or events were observed than expected from the standard population (better health than standard population)

SMR equation

SMR = observed / expected observed death or cases in the population / expected number of death or cases from population you're interested, assuming the risk is the same

YPLL

Years of potential life lost - a measure of premature or early death each deceased persons age is subtracted from a predetermined age at death. Sum up each persons years of potential life lost

two methods for calculating age adjusted rates

direct and indirect (SMR)

proportionate mortality

number of death due to a particular cause / number of deaths from all causes Proportionate mortality describes the proportion of deaths in a particular population over a specified period of time, attributable to different causes

Cause specific death rate

number of deaths assigned to a specific cause during a given time interval/size of the population which deaths occured The mortality rate for a specific cause in a population

maternal mortality rate

number of deaths assigned to pregnancy related causes during a given time interval / number of live births during the same time interval

Case fatality rate

number of deaths of a particular disease during a specific period / number of individuals with that specific disease estimates the proportion of persons contracting a disease who die from the disease

Infant Mortality rate

number of deaths under 1 year of age in a given time interval / number of live births reported during the same time interval

Direct age adjusted death rates

•Calculation steps: 1. indentify the standard population 2. calculate the expected # of death using the standard population 3. Apply the formula: expected deaths using standard population during a given time period / standard population