Ph 150A Final Exam Study Guide

PH 150A FINAL EXAM STUDY GUIDE


endemic - ANSWER usual presence of disease within a given geographic area

epidemic - ANSWER occurrence of disease of a similar nature which is clearly in excess
of normal expectancy in a community or region and derived from a common source

pandemic - ANSWER refers to worldwide epidemic

primary prevention - ANSWER prevent the initial development of disease (education,
immunization)

secondary prevention - ANSWER early detection of existing disease;

screen or survey populations (ideally "high risk" populations) to find early disease and
treat before it becomes established;

use surveillance systems to identify high risk groups

tertiary prevention - ANSWER reduce impact of a disease;

treat established disease to avoid progression and complications of disease

John Snow - ANSWER conducted first comprehensive epidemiologic study (descriptive,
analytic, study design);

believed cholera outbreak due to water contamination;

course of disease (agent, mode of transmission, clinical manifestation);

population-based thinking and solutions;

"shoe-leather epidemiology"

epidemiologic approach - ANSWER to describe the health status of populations (cases
of disease, frequency, trends);

to explain the etiology and natural history of disease (causal factors, modes of
transmission)

sources of data - ANSWER interviews

physician records

hospital records

passive surveillance - ANSWER routine data used or physician or lab reports cases of
disease;

,inexpensive, not comprehensive

active surviellance - ANSWER project staff seek out cases of disease;

expensive, more comprehensive

sentinel surveillance - ANSWER intensive collection of case data from only part of the
population;

monitoring key health events through specific sites, providers, vectors;

ex: active surveillance at specific hospitals to track specified disease

National Notifiable Disease Surveillance (NNDS) - ANSWER reporting mandated by state
law;

health care providers, labs reports to local health department;

county health dept submits reports to state health dept;

reports sent to CDC

rates - ANSWER how fast the disease occurs in population;

time included in the denominator

ratio - ANSWER one number or rate relative to another;

note: a proportion is a type of ratio, but not all ratios are proportions; a rate can also be
considered a type of ratio but not all ratios are rates

counts - ANSWER absolute number of occurrences;

useful for public health efforts, burden of disease



proportions - ANSWER what fraction of population is affected;

numerator always included in denominator



measures of disease (morbidity) - ANSWER prevalence (point prevalence, period
prevalence)

incidence (cumulative incidence, incidence density)



prevalence - ANSWER fraction of a population having a specific disease at a given time;

"snapshot" of existence of disease;

,a proportion



point prevalence - ANSWER number of existing cases at a certain point in time (a
specific date);

most commonly used



period prevalence - ANSWER number of existing and new cases during a given period
(month, 5-year period)

denominator = all persons in population present at midpoint of period

numerator is subset of demonitator (proportion)



benefits of prevalence measures - ANSWER characterize the burden of disease;

aids in allocation of resources



limitations of prevalence measures - ANSWER can change depending on:

-when you measure it

-how many people die

-how many people get disease

-length of time person has disease/health related state



incidence - ANSWER number of NEW cases of disease that occur during a specified
period of time in a population AT RISK for developing the disease;

measure of events;

measure of risk (probability);

values range from 0 to 1



cumulative incidence - ANSWER proportion of persons who develop a new outcome
during a specific time period;

estimates your risk of disease (probability);

, denominator: those "at risk" (disease free) at beginning or period;

assumes everyone in population (denominator) is followed for the entire time-period or
at risk for entire time;

must include statement about time period (# of cases per month, year);

aka incidence proportion, cumulative incidence rate;

places individual with outcome in numerator and leaves individual with outcome in
denominator;

underestimates risk



incidence density - ANSWER number of new cases in a specific time period/total
person-time;

"person-time": sum of disease-free time each individual contributes during the time
period;

a true rate because time is in denominator (person-years, person-months);

more precise denominator than cumulative incidence;

limitations: takes more time and effort

places individual with outcome in numberator and removes individual with outcome
from denominator;

considers when the outcome occurred, not just if it occurred



Behavioral Risk Factor Surveillance System - ANSWER largest telephone survey in the
world;

established by CDC in 1984;

collects information monthly



National Health and Nutrition Examination Survey (NHANES) - ANSWER survey on
obesity in US;

more than 1 in 3 adults considered overweight;

more than 2 in 3 adults considered overweight or obese;

more than 1 in 3 adults considered obese;