What it means
The insurer believes there is not yet enough published evidence to consider the service standard care for the specific condition being treated. Each insurer maintains its own policy and the same service can be standard care at one plan and investigational at another.
Why it changes over time
These policies are updated as new clinical evidence is published. A service that is investigational this year may be standard next year — and vice versa.
What to do
Ask your provider whether there are clinical-trial pathways, manufacturer assistance programs, or alternative services the plan does cover. If you proceed, ask for a written cost estimate so you are not surprised by the bill.