Copyright © 2008 Delmar. All rights reserved. Chapter 4 Epidemiology and Public Health Nursing

Copyright © 2008 Delmar. All rights reserved. 2 Epidemiology Relatively new study of distribution and determinants of health in populations Epidemiologist –Assists in research studies –Serve local and state health departments –CDC

Copyright © 2008 Delmar. All rights reserved. 3 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

Copyright © 2008 Delmar. All rights reserved. 4 Epidemiologic Models Components –Person Susceptibility –Place Location –Time Characterized by a disease

Copyright © 2008 Delmar. All rights reserved. 5 Health-Related Studies Case reports –Report of an individual –Oddities Case series –Involves 2-10 individuals –Anecdotal information

Copyright © 2008 Delmar. All rights reserved. 6 Health-Related Studies Epidemiologic studies –Generalized to an aggregate or population –Smallest sample 10 cases and 20 controls

Copyright © 2008 Delmar. All rights reserved. 7 Community Assessment Requires data collection from several sources: –Vital statistics –Census data –Prevalence studies –Incidence studies

Copyright © 2008 Delmar. All rights reserved. 8 Community Assessment Mortality studies –Surveillance data –Youth Risk Behavioral Survey –Behavioral Risk Factor Surveillance System

Copyright © 2008 Delmar. All rights reserved. 9 Community Assessment Convenience samples –Rarely acceptable Nonscientific method of sampling

Copyright © 2008 Delmar. All rights reserved. 10 Community Assessment Epidemiology studies use random samples to decrease potential bias Screening –Classification of individuals who have a likelihood of a certain disease

Copyright © 2008 Delmar. All rights reserved. 11 Screenings Used on asymptomatic individuals –Benefits Cheaper Reaches more people –Screening method must be: Sensitive Specific Epidemiology

Copyright © 2008 Delmar. All rights reserved. 12 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

Copyright © 2008 Delmar. All rights reserved. 13 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

Copyright © 2008 Delmar. All rights reserved. 14 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

Copyright © 2008 Delmar. All rights reserved. 15 Epidemiologic Rates Rates –Measure frequency of health events –Determined by statistical adjustments to raw data

Copyright © 2008 Delmar. All rights reserved. 16 Epidemiologic Rates Prevalence –Proportion of a given population diagnosed with a certain disease # of existing cases Total population

Copyright © 2008 Delmar. All rights reserved. 17 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

Copyright © 2008 Delmar. All rights reserved. 18 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

Copyright © 2008 Delmar. All rights reserved. 19 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

Copyright © 2008 Delmar. All rights reserved. 20 Types of Epidemiologic Studies Studies related to current level of knowledge –Cross sectional studies Observational study Conducted over a brief period

Copyright © 2008 Delmar. All rights reserved. 21 Types of Epidemiologic Studies Studies related to current level of knowledge –Case control studies Observational –Odds ratio Subjects are asked questions only

Copyright © 2008 Delmar. All rights reserved. 22 Cohort Study Largest of observational studies Follows a group of people through time Prospective design –Framingham study Retrospective design Relative risk

Copyright © 2008 Delmar. All rights reserved. 23 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

Copyright © 2008 Delmar. All rights reserved. 24 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