Transcript Chapter 4
Chapter 4 Epidemiology and Public Health Nursing Copyright © 2008 Delmar. All rights reserved. Epidemiology • Relatively new study of distribution and determinants of health in populations • Epidemiologist – Assists in research studies – Serve local and state health departments – CDC 2 Copyright © 2008 Delmar. All rights reserved. Epidemiologic Models • Host-Agent-Reservoir Model – Epidemiologic triangle – Focuses on infectious disease • Person-Place-Time Model – Focuses on chronic disease, but can be used on infectious diseases – Used to identify susceptibility to bacterium 3 Copyright © 2008 Delmar. All rights reserved. Epidemiologic Models • Components – Person • Susceptibility – Place • Location – Time • Characterized by a disease 4 Copyright © 2008 Delmar. All rights reserved. Health-Related Studies • Case reports – Report of an individual – Oddities • Case series – Involves 2-10 individuals – Anecdotal information 5 Copyright © 2008 Delmar. All rights reserved. Health-Related Studies • Epidemiologic studies – Generalized to an aggregate or population – Smallest sample • 10 cases and 20 controls 6 Copyright © 2008 Delmar. All rights reserved. Community Assessment • Requires data collection from several sources: – Vital statistics – Census data – Prevalence studies – Incidence studies 7 Copyright © 2008 Delmar. All rights reserved. Community Assessment • Mortality studies – Surveillance data – Youth Risk Behavioral Survey – Behavioral Risk Factor Surveillance System 8 Copyright © 2008 Delmar. All rights reserved. Community Assessment • Convenience samples – Rarely acceptable • Nonscientific method of sampling 9 Copyright © 2008 Delmar. All rights reserved. Community Assessment • Epidemiology studies use random samples to decrease potential bias • Screening – Classification of individuals who have a likelihood of a certain disease 10 Copyright © 2008 Delmar. All rights reserved. Screenings • Used on asymptomatic individuals – Benefits • Cheaper • Reaches more people – Screening method must be: • Sensitive • Specific • Epidemiology 11 Copyright © 2008 Delmar. All rights reserved. Screenings • Criteria to use prior to initiating a screening program – Natural history and preclinical phase exists long enough to be detectable – Known and effective treatment – Access to facilities for follow up – Disease is not rare 12 Copyright © 2008 Delmar. All rights reserved. Program Evaluation • Criteria – Assessment of objectives – Did the participants improve? • Did they improve more than the comparison group? – Costs of the program? – Per person cost 13 Copyright © 2008 Delmar. All rights reserved. Program Evaluation • Did participants value the program? – Did the providers value the program? • Evaluations – May be expensive – Cost less than the continuation of an ineffective program 14 Copyright © 2008 Delmar. All rights reserved. Epidemiologic Rates • Rates – Measure frequency of health events – Determined by statistical adjustments to raw data 15 Copyright © 2008 Delmar. All rights reserved. Epidemiologic Rates • Prevalence – Proportion of a given population diagnosed with a certain disease # of existing cases Total population 16 Copyright © 2008 Delmar. All rights reserved. Epidemiologic Rates • Incidence – What proportion of a given population was newly diagnosed during the year – May use a different time frame # of new cases in a given time Population at risk 17 Copyright © 2008 Delmar. All rights reserved. Epidemiologic Rates • Risk – What is the likelihood of contracting a disease? – Calculated from incidence rate • Morbidity – Illness or disease – Reported in terms of prevalence and incidence rates 18 Copyright © 2008 Delmar. All rights reserved. Epidemiologic Rates • Mortality – Death rates • Age-adjusted – Some diseases are influenced by age – Must be considered in data analysis – Actual age specific disease rate multiplied by new population distribution to provide an expected number of disease 19 Copyright © 2008 Delmar. All rights reserved. Types of Epidemiologic Studies • Studies related to current level of knowledge – Cross sectional studies • Observational study • Conducted over a brief period 20 Copyright © 2008 Delmar. All rights reserved. Types of Epidemiologic Studies • Studies related to current level of knowledge – Case control studies • Observational – Odds ratio • Subjects are asked questions only 21 Copyright © 2008 Delmar. All rights reserved. Cohort Study • Largest of observational studies • Follows a group of people through time • Prospective design – Framingham study • Retrospective design • Relative risk 22 Copyright © 2008 Delmar. All rights reserved. Randomized Clinical Trial • Experimental study • Often used to study: – Safety and efficacy of new drugs – Lifestyle changes • Can be used in health promotion and disease prevention 23 Copyright © 2008 Delmar. All rights reserved. Sources of Epidemiologic Data • • • • Census Bureau National Center for Health Statistics National Health Interview Survey National Health and Nutrition Examination Survey • Centers for Disease Control • Behavioral Risk Factor Surveillance Survey • Surveillance, Epidemiology, and End Results 24 Copyright © 2008 Delmar. All rights reserved.