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How can GPs help ensure #covid19 #antibody tests are used wisely? 100,000 (or is it 200,000?) tests a day is only useful if we get the right test, for the right patient and the right time. Thread 
GPs have been told to offer antibody testing to anyone having their blood taken who wants to know whether they have been infected with covid-19, even if there is ânot a specific clinical indicationâ http://www.pulsetoday.co.uk/news/gps-to-provide-covid-antibody-testing-for-patients-who-have-bloods-taken/20040894.article
This could cause harm:
Accuracy of these tests needs further evaluation
Wonât change anything for most patients https://www.bbc.co.uk/news/health-52762939
False positive results could reduce compliance with social distancing in those who assume they are immune
Wasted NHS resource
Wasted GP time
Accuracy of these tests needs further evaluation
Wonât change anything for most patients https://www.bbc.co.uk/news/health-52762939
False positive results could reduce compliance with social distancing in those who assume they are immune
Wasted NHS resource
Wasted GP time
BUT â this doesnât mean antibody testing is useless â itâs really important for seroprevalence studies to help us understand how many people have been exposed to covid-19, to help ensure lockdown measures are released at the right time and to plan future healthcare
It could also be helpful for:
-untested patients with prolonged atypical ?covid symptoms
-symptomatic pts who present too late for swabs
-those with -ve swab tests
Might reduce risk of missing other diagnoses where we assume symptoms are covid-related https://www.bmj.com/content/369/bmj.m1881
-untested patients with prolonged atypical ?covid symptoms
-symptomatic pts who present too late for swabs
-those with -ve swab tests
Might reduce risk of missing other diagnoses where we assume symptoms are covid-related https://www.bmj.com/content/369/bmj.m1881
We need better evidence on accuracy and resources to explain this to patients. Remember that if a test is 98% âaccurateâ this doesnât mean result will be correct 98% of the time! Can get surprisingly big problems caused by small errors in testing: https://theconversation.com/coronavirus-surprisingly-big-problems-caused-by-small-errors-in-testing-136700
But don't be scared of Bayes' theorem - GPs are practised at interpreting tests in the context of signs and symptoms, and dealing with uncertainty is what we do.
Remember, time since symptom onset is really important for antibody testing - this paper has a helpful infographic to help interpret results https://jamanetwork.com/journals/jama/fullarticle/2765837
Let's not shy away from being involved in testing - but make sure it is clinically led! We must not be complicit in a government drive to meet meaningless targets through scattergun testing of people with âno specific clinical indicationâ.
