Should ELISA screening be mandatory? Everything you need to argue either side, and the science you must get right to argue either one.
You will be assigned a side on the day, which means you prepare both. An argument you cannot state in its strongest form is an argument you do not understand.
Time: Prepared at home, argued in class.
The ELISA is one of the most used tests in all of medicine. It screens donated blood, confirms infections, measures hormones, and finds allergies. When a test result comes back as a number rather than a yes or no, an assay like this one usually produced it.
You cannot argue about a test you cannot describe. Before any position, you have to be able to say what an ELISA actually does. Fill this in from Friday's lecture without looking it up.
In four steps, what happens in an ELISA well?
What is the wash step for, and what happens to the result without it?
What does the colour at the end actually measure?
A test used on people who are unlikely to have a condition produces mostly false alarms, even when the test itself is excellent. That is not a flaw in the chemistry. It is arithmetic, and it is the single most misunderstood idea in diagnostic testing.
This is the part both sides get wrong, so whichever side you are given, knowing it is an advantage.
Sensitivity is how good a test is at catching people who do have the condition. Specificity is how good it is at clearing people who do not. A screening test is usually tuned for high sensitivity, which means it accepts some false alarms on purpose.
Now the part that surprises people. If a condition is rare, then even an excellent test produces more false positives than true positives, because there are so many more people without the condition than with it. Nothing is wrong with the test. It is arithmetic.
A worked example, given to you. Suppose a condition affects 1 person in 1,000, and the test catches 99 out of 100 true cases and wrongly flags 2 out of 100 healthy people.
Test 100,000 people. About 100 have the condition, and the test finds about 99 of them. About 99,900 do not, and the test wrongly flags about 2 percent of them, which is about 1,998 people.
So about 2,097 people get a positive result, and only 99 of them actually have it. Roughly one positive in twenty-one is real. This is exactly why a positive screen is followed by a confirmatory test and is never, on its own, a diagnosis.
Redo that arithmetic for a condition affecting 1 person in 100 instead of 1 in 1,000. How many of the positives are real now?
What does your answer suggest about WHO a screening programme should be offered to?
Build the FOR case. Write the strongest version, whether or not you agree with it. You will not know your assigned side until the day.
Early detection: what changes for a patient found early rather than late?
Protecting others: which conditions affect people beyond the patient, and how?
Fairness of access: how can a mandatory programme reach people a voluntary one misses?
Cost: what does a late diagnosis cost, in money and in life, compared to a screening programme?
Build the AGAINST case. Write the strongest version, whether or not you agree with it. You will not know your assigned side until the day.
Consent: what does mandatory mean for a person's right to decide about their own body?
False positives: using your arithmetic from SEC 02, what happens to the people wrongly flagged?
Privacy: who else learns the result, and what could they do with it?
Trust: what happens to people's willingness to seek care if testing stops being a choice?
Finish with the two things that actually get graded: the objection you find hardest, and where you stand.
The single strongest point against your own view, written in its best form:
Your honest answer to it, or an honest statement that you do not have one yet:
Where you stand BEFORE the debate:
Where you stand AFTER the debate. Changing your mind in response to evidence is worth full marks:
The rule for the debate itself. You may attack an argument. You may not attack a person. Every claim about what a test can do must match what we learned it does on Friday, and I will stop the debate to correct a science error on either side.
Everything argued in this room is a classroom argument about policy. Nobody in this debate diagnoses anybody, and no position taken here is medical advice or a statement about any real person's health.