Criteria for Screening Flashcards
In what ways is screening different from normal clinical medicine?
1) . The patients/families believe themselves to be well and this gives us a particular burden of responsibility.
2) . The initial test does not in itself give a definitive answer. It simply separates those who are more likely to have the condition (and require follow up) from those who are less likely to have it.
How can screening be defined?
Screening is a public health service in which members of a defined population who do not necessarily perceive they are at risk of, or already affected by, a disease or complication are asked a question or offered a test, to identify those individuals who are more likely to be helped than harmed by further tests or treatments to reduce the risk of disease or its complications.
Describe the genesis of the screening criteria.
The clamour for multiphasic annual examination and a wide range of screening activity in the 50s and 60s prompted a Nuffield Trust Working Party, 1968. The resulting essays made the case for an expert advisory group.
The WHO commissioned Wilson and Junger to produce a Public Health Paper, 1968.
These were later modified.
Describe the criteria for a condition that may be considered for screening.
The Condition:
The condition should be an important health problem.
The epidemiology and natural history of the condition should be understood and there should be a detectable disease marker, latent period, or early asymptomatic stage.
All the cost-effective primary prevention interventions should have been implemented as far as practicable.
Describe the criteria for a test that may be considered for use in a screening programme.
The Test:
There should be a simple, safe, precise and validated screening test.
The distribution of test values in the target population should be known and a suitable cut-off level defined and agreed.
The test should be acceptable to the population.
There should be an agreed policy on the further diagnostic investigation of individuals with a positive test result.
Describe the criteria for a treatment that may be considered for use in a screening programme.
The Treatment:
There should be an effective treatment or intervention with evidence of early treatment leading to better outcomes that late treatment.
Clinical management of the condition and patient outcomes should be optimised prior to participation in a screening programme.
There should be evidence from high quality randomised controlled trials that the screening programme is effective in reducing mortality and morbidity.
Describe the criteria for the actual screening programme.
The Screening Programme:
The benefit from the screening programme should outweigh the harm.
The cost of the screening programme should be economically balanced in relation to expenditure on medical care as a whole (i.e. value for money).
Adequate staffing and facilities for testing, diagnosis, treatments and programme management should be available prior to the commencement of the screening programme.
Informations explaining the consequences of testing, investigation and treatment should be available to potential participants to enable informed choice.
What is meant by the term rare disease?
A disease that has a prevalence of fewer than 1 in 2000 in the population.
Describe the difficulties in applying screening programmes to rare diseases.
When considering some of the criteria of screening programmes it becomes apparent that they are difficult to apply to rare diseases……
There should be evidence from high quality Randomised Control Trials that the screening programme is effective in reducing mortality or morbidity - difficult to do randomised controlled trials for rare diseases.
Adequate staffing and facilities for testing, diagnosis, treatment and programme management should be available prior to the commencement of the screening programme - services are patchy and are not equitable for rare diseases.
Clinical management of the condition and patient outcomes should be optimised prior to participation in a screening programme - for rare diseases management is not optimised.
Information explaining the consequences of testing, investigation and treatment should be available to potential participants to enable informed choices - this information is not available for rare diseases.
Many of the things we screen for are rare diseases.
What are some of the political considerations associated with screening?
People feel strongly abut rare and serious conditions.
Families feel isolated and overlooked.
Clinicians feel ignored and under-resourced by policy makers.
Policy makers feel that specialists may get things out of proportion and lose the larger public health context.
Knox in 1982 wrote: It is an unfortunate fact that many questions relating to the planning and development of screening services during the last 20 years have been based on little more than confrontation between enthusiasts and skeptics and the scientific workers themselves have often been classified as for or against, and their data and conclusions have been believed or discounted more according to the supposed category of their originators than according to their factual content and analytical validity.
If we are not careful it can become very polarised.
Describe the changes to newborn screening in England that were made in January 2015.
In January 2015 the Newborn Blood Spot Screening Programme was expanded in England to include 4 additional inherited disorders that affect metabolism of particular amino acids.
1) . Homocystinuria (HCU) - This disorder affects the metabolism of the amino acid methionine and leads to a build up of homocysteine.
2) . Maple Syrup Urine Disease (MSUD) - An autosomal recessive disorder that affects the metabolism of the amino acids leucine, isoleucine and valine.
3) . Glutaric Aciduria type 1 (GA1) - This disorder affects the metabolism of the amino acids lysine, hydroxylysine and tryptophan which can lead to an accumulation of glutaric acid, glutaconic acid, glutaryl-CoA and 3-hydroxyglutaric acid.
4) . Isovaleric Aciduria (IVA) - This disorder disrupts the metabolism of the amino acid leucine.
This followed a pilot study at five centres that began in 2012 and resulted in the recommendation to expand the existing screening programme.
Homocystinuria (HCU) affects the metabolism of which amino acid(s)?
Homocystinuria (HCU) - This disorder affects the metabolism of the amino acid methionine and leads to a build up of homocysteine.
Maple Syrup Urine Disease (MSUD) affects the metabolism of which amino acid(s)?
Maple Syrup Urine Disease (MSUD) - An autosomal recessive disorder that affects the metabolism of the amino acids leucine, isoleucine and valine.
Glutaric Aciduria type 1 (GA1) affects the metabolism of which amino acid(s)?
Glutaric Aciduria type 1 (GA1) - This disorder affects the metabolism of the amino acids lysine, hydroxylysine and tryptophan which can lead to an accumulation of glutaric acid, glutaconic acid, glutaryl-CoA and 3-hydroxyglutaric acid.
Isovaleric Aciduria (IVA) affects the metabolism of which amino acid(s)?
Isovaleric Aciduria (IVA) - This disorder disrupts the metabolism of the amino acid leucine.
