Module2 - Midterm Flashcards
Public health surveillance
ongoing systematic collection, analysis, and interpretation of health-related data essential to the planning, implementation, and evaluation of public health practice
Passive surveillance
in which available data on reportable diseases are used or in which is mandated or requested by the government or the local health authority. Often falls responsibility on the physician.
Underreporting and lack of completeness are likely
Active surveillance
system in which project staff are specifically recruited to carry out a surveillance program.
Recruited to make periodic field visits to health care facilities such as clinics, primary health centers, and hospitals.
Which type of surveillance is more accurate?
active surveillance because they have been specifically employed and trained to carry out this responsibility
public health surveillance is closely integrated with?
timely spread of the data to those who need to know for the application of these data to prevention and control
Purpose of Public Health Surveillance
- Track conditions of public health importance
- Assess public health status
- Define public health priorities
- Evaluate programs
- Develop public health research
Tracking condition of public health importance includes:
Detection of outbreaks, clusters, and epidemics
Portrayal of the natural hx of disease of injury
monitor change in infectious agents
How we track - Assessing public health status includes:
Quantitative estimates of the magnitude of a health problem in a population at risk ; Monitoring of isolation activities
Prevalence per 1000
No. of cases of a disease present in the pop. at a specified time / No. of persons in the pop. at that specific time x 1000
How we track - Defining Public health priorities include:
Documentation of the distribution and spread of a health event
detection of changes in health practice
facilitate planning
How we track - Evaluating Programs in Public Health Surveillance includes:
Plan public health actions and use of resources
Apprpriation/allocation of prevention of resources
Evaluation of control/prevention measures
Assess quality of health care
Assess safety of drugs, devices, diagnostics, or procedures
How we track - Developing PH resources in Public Health Surveillance includes:
generating hypothesis about etiology and in a limited way, test hypotheses
facilitation of epidemiological/lab research
PHS collection should be ____
systemic and ongoing
Research vs Public Health Surveillance
Research must go through IRB (Review board) takes data from certain population and extrapolates to generalize for bigger pop.
PHS is considered practice not research - it is required, does not require consent, however, if you take data from PHS and are going to analyze it, it could be research
epidemiologists role in PHS
look at, analyze, and interpret data, keeping in mind that it will be used for something; know that it will be disseminated
Purpose of Surveillance - answers the questions:
Who, What, When, Where (questions related to descriptive analysis)
NOT THE WHY!! (no terms of causation)
Conditions (to determine disease) for PH surveillance:
Public Health importance
Prevention, control, treatment ability
Capacity for Control and Prevention
PHS Loop Order:
Collection –> Analysis –> Interpretation –> Dissemination
Dissemination needs to be (ideally) timely for big public health action
Surveillance may also be carried to assess changes in _____
environmental risk factors for disease
***This monitoring may give an early warning about a possible rise in rates of disease associated with that environmental agent.
death rate is _____ in groups with more severe illness such as those who hospitalized
proportionately greater
Which sources of at a can be used to obtain information about the person’s illness?
For hospitalization: medical and hospital records useful
If hospitalization is not required: primary care providers’ record may be the best source
Rates
tell us how fast the disease is occurring in a population
proportions
tell us what fraction of the population is affected
Incidence Rate Definition and Equation
number of new cases of a disease that occur during a specified period of time in a population at risk for developing the disease
No. of new cases of a disease occurring in the pop during a specified period of time / No. of persons who are at risk of developing the disease during that period of time x 1000
The critical element in defining incidence rate is _____ of disease
new cases
*** disease is identified in a person who develops the disease and dod not have the disease previously
the incidence rate is a measure of ___
risk
For an incidence rate to be meaningful, any individual who is included in the denominator must have ____
the potential to become part of the group that is counted in the numerator
incidence density
When different individuals are observed for different lengths of time, in which the denominator consists of the sum of the units of time that each individual was at risk and observed.
What is the difference between incidence and prevalence?
Prevalence can be viewed as a snapshot or slice through the population at a point in time in which we determine who has the disease and who does not.
Incidence includes only new cases or events and a specified a time period
Point Prevalence
Prevalence of the disease at a certain point int is - this is the use of term prevalence
Period Prevalence
People who have had the disease during a time period
- time period can be selected such as month, etc.
Why do we bother to estimate prevalence?
Prevalence is an important and useful measure of the burden of disease in a community to inform rescue allocation by decision-makers. We also want to make future projections and anticipate the changes that are likely to take place.
If we want to look at the cause, of the disease, we must explore the relationship between an exposure and risk of disease, we need data on?
incidence
Mortality Rate Equation
Total no. of deaths from all causes in 1year / No.of persons in the pop. at midyear x 100000
specific rate
When a restriction is placed on a rate
Ex: putting age as a restriction on mortality rate
Case-fatality Equation
No. of individuals dying during a specified period of time after specific disease onset / No. of individuals with specified disease x 100
What is the difference between case fatality and a mortality rate?
In a mortality, rate the denominator represents the entire population at risk of dying from the disease including those who have and those who don’t have disease.
In cases-fatality, denominator is limited to those who already have the disease.
case-fatality is a measure of what?
severity of the disease
Proportionate Mortality
No.of death from cardiovascular diseases in the US in 2015 / Total deaths in the US in 2015. x 100
YPLL
measure of premature mortality, or early death.
The younger the age at which death occurs, _____ of potential life are lost
more years
YPLL can assist in three important public health functions:
- establishing research and resource priorities
- surveillance of temporal trends in premature mortality
- evaluating the effectiveness of program interventions
A mortality rate is a good reflection of the incidence rate under two conditions:
- when the case-fatality rate is high
- duration of disease is short
___ is the single most important predictor of mortality
age
The people conducting surveillance should: (5)
1 identify, define, and measure the health problem of interest
2. collect and compile data about the problem, and possible the factors that influence it
3. analyze and interpret the data
4. provide these data and their interpretation to those responsible
5. monitor and periodically evaluate evaluate the usefulness and quality of surveillance
What are the characteristics of surveillance? (4)
- Timeliness: implement effective control measures
- Representation: provide an accurate picture of the temporal trend
- Sensitivity: to allow identification of individual persons with disease to facilitate treatment, quarantine,
- Specificity: exclude persons not have disease
In certain countries, selection of a health problem, is based on?
prioritizing disease, review of available morbidity and mortality data, knowledge of diseases, geographic and temporal patterns, impressions of public and political concerns
Syndromic surveillance
Surveillance using less specific criteria such as constellation of signs and symptoms, chief complaints, presumptive diagnoses
What is the goal of syndromic surveillance?
provide and earlier indication of an unusual increase in illness than traditional surveillance might, to facilitate early intervention.
Sentinel Surveillance
Pre-arranged sample of health care providers or others who agree to report cases of a certain disease
What is the Major infectious disease surveillance system
NNDSS: states can choose what to include in their laws regarding reportable conditions –> they primarily use the CDC/CSTE definitions but not necessarily.
State-Based Notifiable Disease
state mandate; NNDSS/NEDSS
- stable, widely used, required
Healthcare Associated Infections
federal requirements/state mandates; NHSN
- stable, widely used, required
Influenza Surveillance
voluntary-except pediatric deaths; Sentinel Surveillance and Syndromic Surveillance
- stable, but not required, but widely used
Big Data Systems, Google Flu, Flu near You
not as stable, use varies, not required
What are the Limitations on ID Surveillance
- Any minor changes may not be easy to detect
- Delayed Detection/Notification - Issues
- Biases: Selection bias (have info on those tested due to clinical disease; Misclassification non-differential (different testing platforms with varying specificities); Misclassification differential (providers may be morel key to test/ report certain groups of people
- Limitation of surveillance data: of utilized beyond intended purpose
____ over _____ for much of surveillance
sensitivity; specificity
Data Sources
General public, environmental conditions, healthcare providers and facilities, non-traditional
Data Collection Methods
Notifications, surveys, registries, environmental monitoring
Will have much higher rates of death in the subset of _____ patients
hospitalized
what are the two frequency measures?
morbidity and mortality
What is the purpose of incidence?
to find cause; explore the relationship between exposure and risk of disease
What is the purpose of mortality?
- Severity
- Proxy for risk –> Casa-fatality high, Disease duration short
What are the issues with morbidity
Defining cases, finding cases, under counting certain groups/populations
What are the issues with mortality
cause of death-underlying cause, changes in definition
What is the goal of adjustment mortality rates?
compare at least two populations and want to eliminate possible effect of a given factor such as age on rates being compared
***Adjusted rates are not “real” rates
Direct adjustment rates?
use an outside, standard population, compare at least two populations (most commonly used)
indirect adjustment rates?
use a population to calculate a standardized number of observed/expected; when number of deaths in each age-specific stratum
