Snapshot There is a city with a population of 500,000. There are 20,000 women of childbearing age. In the year 2020, there are 20 maternal deaths and 200 live births. The maternal mortality rate is 20/200 = 0.1. Introduction Overview login to view 1 more bullet Crude mortality rate login to view 3 more bullets Cause-specific mortality rate login to view 4 more bullets Case-fatality rate login to view 2 more bullets Attack rate login to view 4 more bullets Maternal mortality rate login to view 2 more bullets Crude birth rate login to view 2 more bullets Prospective and Retrospective StudiesProspective studiespatients enrolled before data collectionparticipants followed over timedata collected on exposures and outcomes as they ariseRetrospective studiesinvolve collecting historical information from a sample of patientsenrollment occurs after exposure and outcome have already occurredCase-Control StudyRetrospective (almost always)Compares patients with and without disease to asses their odds of a certain exposureOdds ratio (OR) is measure of disease associationOR= odds of exposure among cases/odds of exposure in non-cases = ad/bcodds of exposure among cases=# cases with exposure/# cases without exposure = a/codds of exposure among non-cases=# non-cases with exposure/# non-cases without exposure=b/d"How much more likely is it that patients with cirrhosis have been exposed to heavy alcohol use compared to controls?"Cohort StudyCan be eitherprospectiveorretrospectiveCompares groups with and without an exposure to assess associations with subsequent diseaseRelative risk (RR) is measure of disease associationRR= incidence rate in exposed group/incidence rate in unexposed group = [a/(a+b)]/[c/(c+d)]incidence rate in exposed group=# of exposed cases/(# total exposed cases and non-cases) = a/(a+b)incidence rate in unexposed group=# of unexposed cases/(# total unexposed cases and non-cases)=c/(c+d)"How much more likely are patients to develop cirrhosis if they are exposed to heavy alcohol use?"Cross-Sectional StudyExposure and outcome are assessed simultaneouslyAscertains association not causalityPrevalenceis measure of disease association"How much higher is the proportion of cirrhosis patients with heavy alcohol use compared to those without cirrhosis?"