Aging baby boomers are not the threat to long-term healthcare budgeting that they’re often accused of, says a new report from federal economists.

Big swings in Medicare payments for procedures and insufficient evidence of what works best clinically are bigger concerns, say study authors from the Congressional Budget Office. It is their first such analysis on the topic.

Differences in payments among geographic regions are also a problem the non-partisan CBO states. Often, outcomes are the same yet costs vary. The agency issued the report to help policy makers evaluate healthcare spending trends in a new way, the head of the CBO said.