Epidemiology Midterm 1

use of epidemiologic evidence

- changing patterns of community health 1. patterns of disease, death, or exposures/behaviors 2. developing and evaluating prevention programs 3. clinical practice

clinical life tables

- fundamental for survival analysis with "time to event" (not always death) - "chance of survival" after... (can be any health event, not just death) - handles variable times of entry and withdrawal - generates a survival curve

objectives of epidemiology

- identify the causes of disease (also called etiology) - study the natural history and prognosis - determine the overall size of the problem in the community (the prevalence) or measure how quickly it is growing in the community (the incidence)

when is a mortality rate a good index of an incidence rate of disease?

- when case fatality is high - when the duration of disease is short

5 ways to express prognosis

1. case fatality rate 2. 5-year survival 3. median survival time 4. relative survival time 5. observed survival time

what're the 8 steps of an outbreak investigation

1. define the outbreak 2. examine the distribution of cases by times, place, time x place 3. look for combination of variables 4. developed hypotheses based on existing knowledge, analogy to other diseases processes 5. test hypothesis (-es) 6. recommend control measures 7. prepare a written report of investigation and findings 8. communicate findings

epidemiological studies

1. experimental study 2. observational study

assumptions for clinical life tables

1. no changes in survivorship over time 2. individuals lost to follow-up are similar to those followed (hard to prove) 3. withdrawal occurs uniformly within intervals 4. event occurs uniformly within intervals

uses of kaplan-meier method

1. takes advantage of all information available in the calculation and is useful for small sample sizes 2. clinical studies use Kaplan-Meier plots to display prognosis over time 3. estimates can be used to compare clinical trials when groups are similar and adjustment is not needed - uses all info given

natural history

= prognosis - the course of a disease from onset (inception) to resolution - tells us infectious stages

clinical trial

a controlled experiment having a clinical event as an outcome measure, done in a clinical setting and involving persons having a specific disease or health condition

epidemic curve

a figure that depicts the distribution of the times of onset of the disease or death

stratum

a layer or level within an ordered system

randomized trial

a trial is an experiment - a clinical trial in which participates are randomly assigned to separate groups that compare different treatments

which of the following statements are true? more than one answer may be correct a. a mortality rate is an example of an incidence rate b. death certificate data are generally valid regardless of the cause of death c. type of disease is the most important predictor of mortality d. changing diagnostic criteria does not affect estimates of prevalence and incidence e. the case-fatality rate is calculated based on the entire population at risk

a. a mortality rate is an example of an incidence rate

in the "years of living dangerously" video on health-related deahts in LA, which sources of data did Dr Rupa Basu use to determine the number of people who died during the heat wave? more than one answer may be correct a. coroner reports b. emergency room electronic needs c. obstetric (pregnancy) clinics d. all of the above e. none of the above

a. coroner reports b. emergency room electronic records

what are the main characteristics of epidemiology? more than one answer may be correct a. it's the study of distributions of diseases and exposures b. its goal is to apply findings to control health problems c. it's the study of the determinants of disease and exposures d. it studies only infectious diseases e. all of the above

a. it's the study of distribution of diseases and exposures b. its goal is to apply findings to control health problems c. it's the study of the determinants of disease and exposures

which best describes prevalence rate? a. number of all cases of a disease divided by the number of people at risk for that disease, in the same community during the same period of time b. number of new cases of a disease divided by the number of people at risk for that disease, all in the same community during the same period of time c. number who became ill and who ate a particular food divided by total number of people who ate the food d. all of the above e. none of the above

a. number of all cases of a disease divided by the number of people at risk for that disease, in the same community during the same period of time

external validity

also called generalizability - a study is generalizable if it produces unbiased inferences about a target population -- beyond those in the study

prevalence

an estimate of the magnitude of the disease burden in a community - what proportion of the community has this disease? - numerator includes BOTH new and existing cases of disease - not a measure of risk; measure of the burden of a disease in a community

indirect method of adjustment (SMR)

assumes that the population under study has the same experience as the reference population and then applies that experience to the study group

the population of Atlantis on march 30, 2012 = 183,000. the number of new cases of measles occurring between january 1 and june 30, 2012 = 26. the number of active measles cases according to the city register on june 30, 2012 = 264. the incidence rate of measles for the 6 month period was: a. 7 per 100,000 population b. 14 per 100,000 population c. 26 per 100,000 population d. 28 per 100,000 population e. 130 per 100,000 population

b. 14 per 100,000 population

which of the following best describes a pandemic? a. the occurrence in a community or region of a group of illnesses of similar nature, clearly in excess of normal expectancy and derived from a common or propagated source b. a worldwide epidemic c. habitual presence of a disease within a geographic area d. a worldwide habitual presence of a disease within a geographic area e. none of the above

b. a worldwide epidemic

which of the following best describes secondary prevention? a. preventing the initial development of a disease b. early detection of existing disease to reduce severity and complications c. reduces the impact of the disease that's usually incurable d. all of the above e. none of the above

b. early detection of existing disease to reduce severity and complications

which best describes the incidence rate? a. number of all cases of a disease divided by the number at risk for that disease, in the same community during the same period of time b. number of new cases of a disease divided by the number of people at risk for that disease, all in the same community during the same period of time c. number who became ill and who ate a particular food divided by total number of people who ate the food d. all of the above e. none of the above

b. number of new cases of a disease divided by the number of people at risk for that disease, all in the same community during the same period

which of the following are examples of a population prevalence rate? a. the number of 3-year old children who developed sore-throats in january 2019 b. the number of persons with diabetes per 100,000 population c. the number of cases of tuberculosis diagnosed in an infectious disease clinic d. B and C e. all of the above

b. the number of persons with diabetes per 100,000 population

which of the following is an advantage of active surveillance? a. requires less project staff b. is relatively inexpensive to employ c. more accurate due to reduced reporting burden for healthcare providers d. relies on different disease definitions to account for all cases e. reporting systems can be developed quickly

c. more accurate due to reduced reporting burden for healthcare providers

if your grandma geraldine's potato salad (potato with mayonnaise) was hypothesized to be the culprit of an outbreak at a church luncheon, what would you expect the epidemic curve to relfect? assume that there was no leftovers. a. multiple waves in the epidemic curve b. one slow growing peak c. one explosively growing peak d. no evidence of a peak e. none of the above

c. one explosively growing peak

which of the following is an example of primary prevention? a. physical therapy for stroke b. screening for cervical cancer c. vaccines to prevent influenza d. medication to slow the progression of chronic kidney disease e. none of the above

c. vaccines to prevent influenza

tertiary prevention

can't prevent disease - reducing impact of disease ex. disability after stroke

internal validity

comparison groups are selected so that the observed differences between them are because of treatment under study - high internal validity if little bias and confounding

which of the following statements are true? more than one answer may be correct a. prevalence rates are always larger than incidence rates b. in a steady state, the prevalence of disease is equal to the attack rate c. diagnostic criteria rarely impact estimates of disease prevalence and incidence d. prevalence rates are useful for public health planning e. incidence rates can be used to estimate prevalence when the mean duration of the disease is known

d. prevalence rates are useful for public health planning e. incidence rates can be used to estimate prevalence when the mean duration of the disease is known

which of the following best describes herd immunity? a. can occur when there is a weak immune response to the vaccine b. requires that all members of the community are immune c. can occur when there is a non-human reservoir for the infectious agent d. resistance of a group of people to an attack by a disease to which a large proportion of the members are immune e. can occur when random mixing is not present

d. resistance of a group of people to an attack by a disease to which a large proportion of the members are immune

which of the following may occur during the incubation period? a. onset of clinical illness b. receipt of infection c. signs and symptoms of disease d. transmission of infection e. isolation of disease carrier through quarantine

d. transmission of infection

which are part of the epidemiologic triad in the case of malaria? a. host b. vector c. agent d. environment e. all of the above

e. all of the above

the population of Atlantis on march 30, 2012 = 183,000. the number of new cases of measles occurring between january 1 and june 30, 2012 = 26. the number of active measles cases according to the city register on june 30, 2012 = 264. the prevalence of measles as of june 30, 2012 was: a. 14 per 100,000 population b. 26 per 100,000 population c. 28 per 100,000 population d. 130 per 100,000 population e. none of the above

e. none of the above

incidence

estimates of the risk of getting the disease - number of NEW cases of a disease that occur during a specified period of time in a population at risk for developing the disease - measure of events -- the disease is identified in a person who develops the disease and didn't have disease previously - measure of RISK

epidemic

excess of normal expectancy

John Snow

father of epidemiology

endemic

habitual presence

prevention

identification of high-risk groups - define how and why they are high-risk and potentially modify those factors before disease - direct preventative measures to high-risk groups likely benefit

experimental study

investigators intervene in the natural history by actively altering one of the variables - conclusions about relationship between the variables based on the outcomes - randomized clinical trials

observational study

investigators use the data observed in the population - conclusions on the relationship between the variables - cohort study, case-control study, cross-sectional study

years of potential life lost (YPLL)

mortality measure that assesses the impact of (premature) death on a community - summing the years that individuals would have lived had they experienced normal life expectancy and not died from particular disease

prevalence rate

number of cases in the population during a specified time DIVIDED BY number of people at risk in the population during a specific time TIMES number ?

proportionate mortality

number of deaths from Disease X in US in 2000 DIVIDED BY number of deaths in US in 2000

cause-specific mortality rate

number of deaths from Disease X in Year Y DIVDED BY number of people in population at midyear

mortality rate

number of deaths from all causes in one year DIVIDED BY number of people in population at midyear

age-specific mortality rate

number of deaths from all causes in one year for specific age group DIVIDED BY number of people in specific age group at midyear

case fatality rate

number of individuals dying during specified time after disease onset/diagnosis DIVIDED BY number of individuals with specified disease

incidence rate

number of new cases in the population during a specified time DIVIDED BY number of people at risk in the population during a specific time TIMES number ?

attack rate

number of people at risk in whom an illness develops divided by total number of people at risk

where do the sources of data come from

numerators and denominators can come from varying source, with varying problems with each

standardized mortality ratio (SMR)

observed deaths DIVDED BY expected deaths MULTIPLIED BY 100

censored

people who leave the study

miriam brailey

performed research on mortality statistics

primary prevention

prevent something before disease has occurred - prior to the disease occurring ex. flu shot

stratified randomization

random assignment within groups by participant characteristics (age, sex, disease severity) intended to ensure good balance of these factors across intervention groups

clinical practice

the practice of medicine, although focused on one patient, is dependent on population data - diagnosis and screening - accuracy of clinical markers and disease - prognosis - natural history of disease - selection of therapy - clinical trials of therapeutic regimens

herd immunity

the resistance of a group of people to an attack by a disease to which a large proportion of the members of the group are immune

epidemiology

the study of the distribution and determinants of health-related states or events in specified populations and the application of this study to control health problems - "distribution" --> where were deaths located - "determinants" --> what caused the death

age AND cause-specific mortality rate

total number of deaths from Disease X in one year for age group X DIVIDED BY number of people in age group X at midyear

kaplan-meier method

very similar to clinical life table method - uses the exact times that events occurred rather than predetermined intervals - rows determined by events, not by researcher

secondary prevention

when disease has started and identified - early detection of existing disease to reduce severity and complications ex. mammogram