Lecture 2, part 1 Flashcards
What are the objectives of epidemiology?
Determine the extent of dz in a pop
ID patterns and trends in dz occurrence
ID the causes of dz
Evaluate the effectiveness of prevention and tx activities
What are the steps in measuring the occurrence of a dz?
Develop a definition of a particular dz
Count the number of people affected by the dz
Determine the size of the pop from which the diseased cases arose
Account for the passage of time
What do case definitions allow for?
Standardization across settings
On what are case definitions usually based?
A combo of physical and pathological exams, diagnostic test results, and signs and sx
Case definitions include what criteria?
Person
Place
Time
Clinical features
Definition of person
Key characteristics that cases share in common
Exs of person
Age group
Sex
Occupation
Race
Definition of place
Specific geographic location or facility
Exs of place
Resident of state or county
Nursing home
School
Definition of time
Linear period of time associated with illness onset
Ex of time
Onset of illness btwn Jan 1 and March 4, 2021
Definition of clinical features
Signs and sx or maybe specific laboratory criteria
Exs of clinical features
SOB
Cough
Fever
What is a conceptual definition?
Theoretical idea of what needs to be measured
Aspects of conceptual definitions
Scientifically defines a specific concept
Generally broad or abstract
What is an operational definition?
What we are actually measuring
Aspects of operational definitions
Redefines the concept in specific measurable terms
How a variable is measured in a given study
Characteristics of early case definitions
May be broad (not specific, increased sensitivity)
As additional information is gathered, what occurs with case definitions?
They become more focused and specific
When will case definitions be more accurate?
When definitions include more specific criteria
On what are case definitions dependent?
The resources and data available
How can case definitions vary? What are the levels of case definitions?
By level of diagnostic certainty
Confirmed
Probable
Suspect
What is the progression of dz?
People are infected
People have sx
They seek care
They could be hospitalized
They could die
These circles get smaller and smaller
What are the various methods for counting cases?
OB ixs
Reportable dz registries
Clinic/hospital records, insurance claims
Vital stats records
Surveys/questionnaires
What are challenges in case counting?
Clinically diagnosed cases often represent only a fraction of all actual cases
Data sources may be limited
What is an ex of case definition changing over time?
HIV
Used to be very limited to unexpected Kaposi’s sarcoma and Pneumocystis carinii pneumonia
Expanded three times more to include antibody testing, CD4 count, and 27 clinical conditions
