Module 3 Flashcards
Disease
Any disruption in the function and structure of the body
An abnormal state in which the body is not capable of responding to or carrying on it’s normally required functions
Morbidity
Any departure from a state of physiological and psychological well-being
Measured by incidence and prevalence
Described by ICD-9 and ICD-10 coding systems
Natural history of disease
Normal course of disease from onset to resolution without treatment or intervention
Epidemiologic surveillance
The ongoing systematic collection, analysis, and interpretation of health data essential to the planning implementation and evaluation of public health practice
Includes timely reporting of data to important agencies
Applications of epidemiologic surveillance
- Monitor changes in disease frequency
- Monitor changes in levels of risk factors
* *Commonly used for infectious diseases
Reportable/notifiable diseases
Reporting mandated by federal and state statutes
Conditions deemed significant to public health
Ex: STDs, measles, foodborne illness, outbreaks, injuries
Advantages of reportable disease data
Standardized case definitions
Availability of lab/clinical data
Comparability of data between jurisdictions
Disadvantages of reportable disease data
Incompleteness of population coverage (ex: asymptomatic case)
Failure of physician to report
Unwillingness to report cases with social stigma
Privacy Act of 1974
Prohibits release of confidential data without consent of individual
Freedom of Information Act
Mandates release of government information to the public except personal and medical files
HIPAA
Restricts access to protected health information
*PHI can be disclosed without patient authorization for public health purposes
Sources of morbidity data
Disease reporting Medical records Insurance claims Population-based morbidity surveys Absenteeism records
Criteria for epidemiologic data
- Nature (source)
- Availability/access
- Completeness of population coverage
- Value and limitations
Syndromic surveillance
Prospective surveillance of nonspecific health indicators (syndromes)
Use existing electronic health related data coded into nonspecific disease syndromes and analyzed in near real-time to monitor trends
Objectives syndromic surveillance
To identify illness clusters early before diagnoses are confirmed and reported to public health agencies
To mobilize a rapid response thereby reducing morbidity and mortality
Use of Syndromic surveillance by public health agencies
- Situational awareness
- Emergency response management
- Outbreak recognition/characterization
Traditional vs. Syndromic surveillance
Traditional: diagnosis-based
Syndromic: prediagnostic (helps with early detection)
*syndromic surveillance does not replace traditional public health surveillance
Measures of disease frequency
- Count
- Ratio
- Proportion
- Rate
*Used to quantify health events in a population (morbidity, mortality)
Count
The number of cases of a disease or other health phenomenon being studied (simplest most frequently performed quantitative measure)
*significant for rare diseases (Ebola)
Ratio
Value obtained by dividing one quantity by another
*relationship between two numbers
No specified relationship between numerator and denominator
Proportion
States a count relative to the size of the group
Ratio in which the numerator is part of the denominator
*can demonstrate the magnitude of the problem
Rate
A ratio in which time forms part of the denominator
Includes:
- Disease frequency
- Unit size of population
- Time period during which an event occurs
Incidence
The number of new cases of a disease that occur in a group during a certain time period
Useful for:
- research on the etiology of disease
- estimating risk of developing disease
- estimating effects of exposure to a factor of interest
Prevalence
Number of existing cases of a disease in a population at some designated time
- indication of the extent of the problem
- estimating frequency of an exposure
- determining allocation of Heath resources such as facilities and personnel
Relationship between Prevalence and incidence
Prevalence = Incidence x Duration
Morbidity frequency measures
Incidence and prevalence
Incidence rate
The rate of development of a disease in a group over a certain time period
(New cases/population at risk) during time period
Incidence density
Used when members of a population or study group are under observation for different lengths of time
Number of new cases during time period/total person-time of observation
Attack rate
Alternative form of incidence used for diseases observed any population for short time period
*not a true rate because time dimension is often uncertain
Point prevalence
(Number of people ill/total number in the group) at a point in time
Period Prevalence
(Number of persons ill/average population) during a time period
Crude rates
Nonspecific rates
*Differences crude rates may be the result of systematic factors within the population rather than true variation in rates; use with caution when comparing between populations
Specific rates
Refer to a particular subgroup of the population
Can be defined in terms of race, age, sex, or single cause of death or illness
