This new guidance from NICE advises that 2 new devices have been approved for home monitoring in warfarin patients with AF or heart valve problems. They are surprisingly cost-efficient for self-monitoring (eg where the patient checks their own levels and acts on them), though not for self-testing (where they just take their levels, then phones up to see what to do with them).
Obviously the patient or their carer needs to be able to understand how to use the machine and then make adjustments accordingly.
The two machines approved are the CoaguChek XS system and the InRatio2PT/INR.
Machines have to be intermittently calibrated.