Transcript 10.21.04
Past subjects=>passed subjects=>subjects passed October 21 2004 Epi 511 What is this? How can you use it to explain occurrence of WNV? Host Vector Agent Environment Herd Immunity • Why is it important for vaccine programs? • What types of “agents” work best to establish herd immunity? • Why do you need a flu shot almost every year? Where is the incubation period? Observable illness Exposure Treatment Infection Pre Clinical period Clinical Period Outcome Infectious disease • Is the “Attack rate” more like prevalence or incidence rate? • Give an example of primary prevention and tertiary prevention. • Does “secondary attack rate” refer to initial disease cases becoming infected with a second disease? Explain. • Endemic : epidemic :: usual : ? Mortality measures • If 4739 pedestrian vs motor vehicle deaths occurred in 2002, and there were known to be 78,000 motor vehicle accidents in that year. What is the case fatality rate? Personalities: What did they contribute to Epi? • • • • • John Graunt William Farr John Snow Joe Goldberger Edgar Sydenstryker Study designs • Describe an Ecologic study of the association between fish consumption and stroke. • Describe a Case-control study of the association between fish consumption and stroke. • Describe a Cohort study of the association between fish consumption and stroke. • Describe a Randomized trial of the association between fish consumption and stroke. Questions about designs • Give an example of “ecologic fallacy” from the study of fish and stroke. • Cross-sectional studies are most valuable in establishing temporal relationships, why or why not? Disease occurrence • How might you determine the prevalence of Parkinson’s disease in Seattle as of July 1, 2003? • How would you determine the incidence of ALS per 100,000 population in King County, in 2003? In 1999? • Suppose the incidence of Pancreatic ca and Multiple Sclerosis were similar, why might their prevalence be similar or dissimilar? Standardization • Comparing mortality rates from diarrheal disease in Somalia relative to Connecticut results in an SMR of 437. What does that mean. • Why would we want to compute SMR? • Is SMR most frequently associated with Direct or Indirect standardization? Occurrence • In Milwaukee, the proportion of deaths due to alcoholism it greater than it is in Cleveland. Therefore, persons in Milwaukee are at greater risk of death from alcoholism? Why or why not. • MS is more prevalent in latitudes farther from the equator. Therefore your risk of MS is greater in Seattle than in L.A. Why/Why not Rates CIt = 1 - e -IDD(t) What does this formula calculate? Why is it useful? Confidence intervals • A confidence interval expresses a summary of the data in original units of measurement. • It reflects the variability in the data, the sample size, and the actual effect size observed. • Includes the “true” value with x% confidence • Agree or disagree with any of the above? Why? Design, Incidence, RR, AR? Exposed Not exposed Subject Develop Person disease? -years ID # Subject Develop Person ID# disease? -years E001 No 6.5 N010 No 6.5 E002 Yes 1.5 N011 Yes 5.0 E003 Yes 5.5 N012 No 6.5 E004 No 3.5 N013 No 3.5 E005 No 2.5 N014 No 4.0 E006 Yes 2.0 N015 Yes 2.5 E007 Yes 6.0 N016 No 6.5 E008 No 1.5 N017 No 5.0