My father had one of the first private-party INR testers. The cartridges needed to be kept refrigerated and in-date, I think ordered monthly. And the machine itself had to be calibrated, tested against a same-day lab test to have it reset properly, either every 30 or maybe 90 days.
I'm sure they've improved by now, but they are nowhere near the convenience of a blood-sugar fingerstick kit.
From the benefits.va.gov web pages:
Health Care for Veterans Living Abroad (Excluding the Philippines)
The Foreign Medical
Program (FMP) Office is responsible for determining eligibility for reimbursed medical
treatment while traveling or residing abroad, except in the Philippines
. Reimbursed medical care for U.S. Veterans residing or traveling in Canada
and other foreign countries is limited to treatment for VA rated service-connected disabilities only. Generally, as long as the service
is medically necessary for the treatment of a VA rated service-connected condition, it will be covered."
So unless your Coumadin is the result of a service
injury...it sounds like they will have no facilities and no reimbursement. You might try calling the US embassy in each of the major spots you plan to visit, and asking what is the most reliable hospital or testing lab in that location, then comparing their costs to what a machine, plus cold-packed air express supplies, plus calibrations, would cost you.
IIRC there's a fairly new drug being pushed as an alternative to Coumadin for some users, which does NOT require the frequent testing. If your doctor is unaware of it, try someone who is more up to the times.