1 in 4 may be on wrong dose of DOACS

One in four patients discharged from hospital on direct-acting oral anticoagulants (DOACs) are likely taking the wrong dose, a Victorian study suggests.

A review of 316 patients discharged in 2016 from a hospital at Eastern Health in Melbourne, revealed 27% were on a DOAC dose that was not appropriate for their weight, renal function, age or indication.

Consultant neurologist Dr Philip Choi, who led the study, said most of the patients were under-dosed.

“We suspect our patient cohort is quite elderly in general, with probably borderline renal function that can fluctuate, and I think there may be an ultra-cautious approach in prescribing,” he told Australian Doctor.

Some patients would have come into hospital on an incorrect dose prescribed by their GP, while others had the wrong dose prescribed by hospital specialists, he said.

DOACS had been marketed as not requiring monitoring, in contrast to warfarin, and this had possibly led to some complacency about their prescribing, he said.

Getting the correct dose required knowledge of the patient’s weight, age and renal function, as well as looking up the product information for the DOAC, said Dr Choi.

Another complicating factor was that the three DOACs —dabigatran, rivaroxaban and apixaban — had slightly different dosing requirements.

“For warfarin, age, weight and renal function don’t come into the equation at all, but for these medicines, these three key bits of information are what you need,” he said.

“This [study] highlights the fact that these medicines are not as easy to prescribe as we think.”

Dr Choi recommended that patients in their 80s underwent a review of their DOAC dose after six months, to check that renal function or weight had not changed significantly.