NON COMMUNICABLE DISEASES, SCREENING AND COMMUNICABLE-OUTBREAK Flashcards
What is mass screening?
Whole population (or subset of population)
What is multiple or multiphasic screening?
Many screening tests at the same time
What is targeted screening?
Groups with particular exposure
What is case finding/opportunistic screening?
Tested while at doctors for another purpose
What is the purpose of screening?
Early detection
When is it ideal to screen?
- Inbetween the early diagnosis stage and usual clinical diagnosis stage (critical point 2)
What are cases of disease determined by?
- Whether symptoms, signs, history and test results are normal (disease absent) or abnormal (disease present)
What is the normal (common) disease given by? (%)
95% normal and 5% abnormal
- Normal distribution 2.5% + 2SD cut off
What results in some healthy people on the abnormal side and vice versa?
- Distribution of measurements being used for both HEALTHY and DISEASED people
- tries to define cut off between the two groups
To meet the requirements of screening, the disease will be…
- Common (prevalent)
- Severe consequences
- Early treatment has better outcomes than no treatment
- Considered a problem by people
- Natural history well understood
- Long preclinical ohase (so disease can be detected by the screening)
To meet the requirements of screening, the test conducted will be…
- Having good accuracy OR high sensitivity and/or specificity
- Be safe
- Simple/ logistically manageable
- relatively cheap
- Acceptable to healthy people
What is an example of diagnostic vs. screening for a woman with breast cancer?
DIAGNOSTIC: The woman found breast lump and goes to doctor the doctors conduct tests to investigate the lump
SCREENING: -Woman with no symptoms has regular screening mammogram
What are some examples of diagnostic tests?
- Colonoscopy
- MRI
- Lumbar puncture
- Digital Rectal Exam
- Biopsy
What are some examples of screening tests?
- FOBT (Faecal Occult Blood Test)
- PSA test (prostate)
- Pap smear
Which parts of the table to sensitivity and specificity look at?
The columns
Which parts of the table do PPV and NPV look at?
- Rows
What is sensitivity ?
The probability of a positive test in people who have the disease (a/total diseased)
What is specificity?
The probability of a negative test in people without the disease (d/nondiseased)
What is specificity checking? (true negative, false negative etc.)
- Checking the true negative people (who have tested negative and are actually negative )
What is sensitivity checking? (true,negative, false negative etc.)
- Checking the true positive (people who have the disease and have tested positive)
What is Positive Predictive Value?
The probability that a person has the disease when the test is positive
What is negative predictive value?
The probability that the person doesn’t have the disease when the test is negative
What do you want to be high to avoid a false negative?
The NPV
What is validity?
- Identifies as many people with the disease and ALSO without it
What does a sensitivity result of 44% mean?
- 44% of people with the disease will be correctly identified as having the disease
- Low value like this suggests test is not good at identifying people WITH the disease
What does a specificity result of 96% indicate?
- 96% were correctly identified as NOT having the disease
- The other 4% got a false positive result
Which setting is the PPV of a test higher in (usually) ?
- HIGH prevalence setting
Which setting is the NPV of a test usually higher in?
- LOW prevalence setting
What is length time bias?
- Screening diagnoses diseases that are less aggressive than those that present clinically
- So you may present with tumors that are non agressive
- Treatments must be safe and effective
What is lead time bias?
- ‘lead time’ is EXTRA TIME you know that you have the disease from screening and makes it appear as if you live longer even if screening doesn’t affect the survival case .
- So survival time shouldn’t be used to evaluate screening test
What are interval cancers?
- Very agressive and presents usually BETWEEN screenings
What is an extension of length time bias?
- Overdiagnosis
- Would never have detected the disease if you hadn’t screened them.
What are NCDs (Non Communicable Diseases) also known as?
- Chronic diseases (e.g. cardiovascular disease)
Are NCDs more prevalent in low, middle or high income countries?
More prevalent in Low and Middle income countries
What was the role of the Ottawa framework?
- To provide new public health promotion strategies in industrialised parts of the world
Is health promotion just about being sick?
NO! It is also about being well
What is an example of equity and equality?
- Two people the same age and gender BUT one breaks their leg due to them living in housing that is of poor condition (unfair and unequal health status)
What is A determinate of health?
- Either factor OR characteristic that brings about change in heath either for BETTER or for WORSE
What are the 3 sections of health determinates?
- Biological
- Behavioural
- Social ( environmental, cultural, economic)
What are social determinates of health?
- Circumstances where people are born, grow up, live, work and age & systems are put into place to deal with illness
What are social circumstances shaped by?
- Economics, social policies and politics
What are the 3 levels that interventions can be targeted at?
DOWNSTREAM
MIDSTREAM
UPSTREAM
What are examples of downstream factors and what level are they?
- biological factors at micro level
- E.g. treatment systems, disease management, investment in clinical research
What are examples of midstream factors and what level are they?
- behavioural factors at intermediate level
- E.g. lifestyle, behavioural and individual prevention
What are examples of upstream factors and what level are they?
- Social factors at the macro level
- E.g government policies, population health, healthy environments
What are socio-ecological approaches from an upstream perspective?
- Infrastructure and systems change (e..g policy and legislation such as seatbelts)
- Community and health development (Engagement, community action)