Screening and Population health Flashcards
What is Primordial screening?
Addressing socio-economic issues
E.g. Improving the quality of housing, building bike or pedestrian trails, legislation to ban indoor smoking, measures for state tobacco control
Risk reduction strategies targeting the population rather than individuals
Focus on social and environmental interventions through legislation or policy changes
Targets the underlying stage of natural disease by targeting the underlying conditions that would eventually lead to disease onset
What is Primary screening?
Measures targeting a susceptible population or individual
Prevent a disease from emerging and generally target healthy individuals
Reduced exposure to risk factors (sunscreens, vaccinations), or identifying and managing risk factors (smoking cessation)
What is secondary screening/prevention?
Secondary Prevention—screening to identify diseases in the earliest. stages, before the onset of signs and symptoms, (subclinical disease) through measures such. as mammography and regular blood pressure testing.
Emphasis is on early detection
e.g. screening programmes (cervical cancer, aortic aneurysm, neonatal hearing and dental checks)
What is tertiary screening/prevention of disease?
Tertiary prevention aims to soften the impact of an ongoing illness or injury that has lasting effects
Measures targeting clinical and outcome stages of the disease
Reduce disease severity and associated complications/sequelae
E.g. rehabilitation after myocardial infarction or stroke, chronic disease management
Quaternary screening or prevention measures do what?
Measures taken to identify patients at risk of over-medicalisation
Targets are patients with illness but no disease
Prevents harmful medical interventions
Medical overuse = unnecessary investigations and treatment that lack patient benefit or bear the potential to cause harm.
What is the difference between disease and illness?
“Disease, then, is something an organ has, illness is something a man has.”
According to this way of thinking, disease is something that needs to be cured, such as infection, injury, toxic exposure, cell degeneration, etc. Illness is something that needs to be managed such as feelings of pain, discomfort, distress, weakness, fatigue, etc.
Obviously, these two things are not mutually exclusive, and they often occur together.
What is the sick role?
The sick role is a concept that concerns the social aspects of becoming ill and the privileges and obligations that come with it.
People with illness and/or disease can choose whether or not to engage with the “sick role”
What is the purpose of screening?
“The purpose of screening is to identify people in an apparently healthy population who are at higher risk of a health problem or a condition, so that an early treatment or intervention can be offered. This, in turn, may lead to better health outcomes for some of the screened individuals.”
What are the Wilson-Junger criteria for?
Assessing whether a screening program will work and if it’s worth doing
- The condition should be an important health problem.
- There should be an accepted treatment for patients with recognized disease.
- Facilities for diagnosis and treatment should be available.
- There should be a recognizable latent or early symptomatic phase.
- There should be a suitable test or examination.
- The test should be acceptable to the population.
- The natural history of the condition, including development from latent to declared disease, should be adequately understood.
- There should be an agreed policy on whom to treat as patients.
- The cost of case-finding (including a diagnosis and treatment of patients diagnosed) should be economically balanced in relation to possible expenditure on medical care as a whole.
- Case-finding should be a continuous process and not a “once and for all” project.
Screening vs Diagnostic tests…
what are the target populations?
Screening
Large numbers of asymptomatic, but potentially at risk individuals
Diagnostic
Symptomatic individuals to establish diagnosis, or asymptomatic individuals with a positive screening test
Screening vs Diagnostic tests…
what is the purpose of each?
screen
To detect potential disease indicators
diagnostic..
To establish presence/absence of disease
Screening vs Diagnostic tests…
what types of testing methods are acceptable?
Screening
Simple, acceptable to patients and staff, should not be harmful
Diagnostic
maybe invasive, expensive but justifiable as necessary to establish diagnosis
Screening vs Diagnostic tests…
What should the positive result thresholds be?
Screening
Generally chosen towards high sensitivity not to miss potential disease - false positive more acceptable than false negative
Diagnosis
Chosen towards high specificity (true negatives). More weight given to accuracy and precision than to patient acceptability - false positive and false negative are both undesirable
What are the aims of screening?
To reduce mortality by early detection and early treatment of a condition
To reduce the incidence of a condition by identifying and treating its precursors
To reduce the severity of a condition by identifying people with the condition and offering effective treatment
To increase choice by identifying conditions or risk factors at an early stage in a life-course when more options are available
Types of Screening
Population-based
Systematically screen every person within a population
Selective
Applied to a particular subset of the population, e.g. high-risk group
Multiphasic
more than one test is applied for more than one condition
Opportunistic
During routine healthcare visits
Note that the above types are not necessarily mutually exclusive, e.g. selective screening can be multiphasic
