Sir, – The recent court ruling that screeners had failed the "absolute confidence" test has serious implications for the viability of all screening programmes in Ireland and many other areas of medicine where human interpretation plays a role ("Judge rules for 'absolute confidence' in screening programmes' all-clear results", News, May 4th).
Reading a smear test can be likened to looking at a field of wheat and trying to spot the few blades of barley scattered in it. The stakes are clearly significantly higher, and screeners know the huge level of responsibility they hold, but it is impossible to be absolutely confident about every smear within an acceptable range of interpretation. One expert’s opinion on subtle abnormalities can be easily challenged by another expert. This leaves highly trained technicians, laboratory scientists and doctors working in an environment where every decision they make can be undermined. The end result of this is an exodus of such staff from areas of medicine where screening and interpretation play a role.
All patients are entitled to the highest standards of care possible. That is a given. However, some balance needs to be restored and an acceptance that medicine, screening and human beings are all fallible. – Yours, etc,
Dr MYRA FITZPATRICK,
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Terenure,
Dublin 6W.
Sir, – The threshold for screening tests has now been set at “absolute confidence”. Absolute suggests 100 per cent sensitivity and 100 per cent specificity: no false positives and no false negatives. Screening tests do not, by their nature, provide this.
Radiologists reporting breast screening mammograms, and those involved in the bowel cancer screening programme, beware ! – Yours, etc,
Dr JOHN RYAN,
Fellow Royal College
of Pathologists,
Drogheda,
Co Louth.
Sir, – Uncertainty is inherent in medical testing and is expressed through the use of statistical significance, confidence intervals, specificity, sensitivity, positive predictive value and other measures.
The legal ruling that the acceptable threshold in cervical screening is “absolute confidence” makes one wish for the simplicity of the courts, where the burden of proof is “beyond a reasonable doubt” in criminal cases and “on the balance of probabilities” in civil law. – Yours, etc,
Dr JOHN DOHERTY,
Vienna.