What an audit covers
A sample of charts is read against the claims that were submitted for them. Findings are reported in both directions — codes billed above what the documentation supports, and codes billed below it. Under-coding is the more common finding and the one that quietly costs the most money.
E/M level distribution
Your distribution of evaluation and management levels is compared against your own documentation. A distribution skewed hard to one level is worth understanding whichever direction it leans, because it usually reflects a habit rather than the actual case mix.
Findings you can act on
You get written findings with the specific charts referenced, the pattern each one illustrates, and what to change. An audit that produces a percentage score and no remediation plan has not told you anything you can use.