Lecture 4 (16/07/21) Flashcards
What are the Core Functions of epidemiology?
Hint: 5 + 1 track
- Public health surveillance
- Field investigation
- Analytic studies
- Evaluation
- Linkages
- Policy development
What is Public Health Surveillance?
the continuous systematic collection, analysis and interpretation of health-related data needed for public health decision making and action
What are the common sources of surveillance data?
morbidity and mortality reports
What is an Alert Threshold?
- when the number of cases rises above the normal threshold
- triggers a respond to act (so that the cases do not become an epidemic/pandemic)
What are some notifiable disease?
- measles
- tetanus
- typhoid
- pertussis
- meningococcal meningitis
- HIV/AIDS
- etc.
What does public health surveillance focus on?
- used to focus on communicable diseases only, now also targets
: injuries
: chronic diseases
: genetic & birth defects
: occupational & environmental- related diseases
: health behaviours
What are some systems for Data Collection?
- electronic
- hard copies
- reports
- etc.
Surveillance provides _______________
information for action
What is Field Investigation?
- done in response to acute public health problems
- when outbreaks of disease occur, there usually is an urgent need to identify the source and/or cause of the problem as a basis for control (to narrow down to the source & prevent further spread/growth)
What are the objectives of field investigation?
- identification of
: additional unreported or unrecognised ill persons
: treatment of contacts
: source/vehicle of infection - to learn more about the natural history, clinical spectrum, descriptive epidemiology, and risk factors of the disease before determining what disease intervention methods might be appropriate
Surveillance and field investigations are usually efficient to identify:
- causes
- modes of transmission
- appropriate control and prevention measures
Methods used in combination
i.e. Surveillance + Field investigation
Explain
provide clues or hypotheses about causes and modes of transmission
Methods used in combination
i.e. Surveillance + Analytic studies
Explain
evaluating the credibility of those hypotheses
How are clusters or outbreaks investigated?
Initially with descriptive epidemiology
Explain Descriptive Epidemiology
Hint: TPP
involves the study of disease incidence and distribution by time, place, and person (TPP)
- includes the calculation of rates and identification of parts of the population at higher risk than others
Define Evaluation
process of determining (as systematically and objectively as possible) the relevance, effectiveness, efficiency, and impact of activities with respect to established goals
Explain Linkages
when epidemiologists work together with another team (multidisciplinary team)
i.e. other team members may. be laboratory scientists, sanitarians, infection control personnel, nurses or other clinical staff, and increasingly, computer information specialists
Explain Policy Development
application of the study [of distribution & determinants of HRE] to the control of health problems
- epidemiologists provide information, advice, guidance regarding disease control strategies, notifiable disease regulations and health-care policy
What are the principles of screening?
Hint: DEEP
- disease prevalent in the population & of reasonable severity
- effective treatment is available
- early detection improves outcome with acceptable morbidity
- pre-clinical stage is detectable
What is Screening?
- a public health intervention intended to improve the health of a ‘defined target population’
- medical tests that doctors use to check for diseases and any health conditions before there are any signs/symptoms
- help find problems early on, when they may be easier to treat
What are the basic criteria for screening?
- recognisable latent / early symptomatic stage
- suitable test or examination
- test acceptable to the population
- should be an agreed policy on whom to treat as patients
What are some examples of screening tests?
- pap smear
- mammogram
- clinical breast exam
- blood pressure determination
- cholesterol level (for hyperlipodemia)
- eye examination / vision test
- urinalysis
- etc.
What is the purpose of screening?
- identification of asymptomatic diseases
- secondary prevention (delays onset & duration of clinical disease with the goal to improve survival)
- determines the presence of disease among apparently healthy patients
What is the Pre-clinical Phase of a disease?
- from the biologic onset of disease to appearance of symptoms of disease
- there may be an interval between the onset of the disease and the occurrence of clinical symptoms during which disease can be detected with certain tests
What is the Clinical Phase of a disease?
from the appearance of clinical symptoms to therapy
Without the diagnosis and therapy of disease, what may happen?
Disease may become terminal
What are the types and levels of prevention?
- Primary Prevention: intervening before health effects occur (removing risk factors)
- Secondary Prevention: screening to identify diseases in the earliest time possible (early detection and treatment)
- Tertiary Prevention: managing disease post diagnosis to slow or stop (reduce complications)
Why is HIV important for screening?
- severe disease with dire consequences
- prevalent in the target population
- has a detectable pre-clinical phase
- treatment at early stage is effective at reducing the disease
What makes a good screening test?
Hint: REACH
R: relatively free of risk / discomfort E: economical A: acceptable to a large number of individuals C: convenient H: highly valid and reliable
Define Validity
ability of a screening test to successfully separate those who have pre-clinical disease from those that do not have it
How is validity measured?
- sensitivity
- specificity
Define Sensitivity
the ability of a test to correctly identify patients with disease (true-positive)
- test for those with the disease
Define Specificity
the ability of a test to correctly identify people without the disease (true-negative)
- test for those without the disease
What is True +ve?
disease present & test is +ve
What is True -ve?
disease absent & test is -ve
What is False +ve?
disease absent & test is +ve
What is False -ve?
disease present & test -ve
