The Chief Medical Officer apology for the distress caused after he sent warning letters to 4800 GPs over their opioid prescribing has been dismissed as an “academic justification for a rubbish project with junk methodology and junk outputs”.

The ­original letters, signed by Professor Brendan Murphy, targeted doctors deemed to be among the top 20% of opioid prescribers, warning that some could face investigation from the Department of Health’s practitioner review program.

They immediately triggered an angry reaction as it became clear that among the recipients were hundreds of doctors working in aged care and pain clinics.

A year later, Professor Murphy admitted flaws in the department’s approach, saying it had not been possible for the department to identify GPs working in palliative care or prescribing for palliative care reasons, and nor had it been possible to identify those GPs who had a specialist pain practice or with “a specific oncology bias” in their patient mix.