Unsupported Diagnoses in Audits: What Gets Challenged and Why

Answer in brief
Unsupported diagnoses get challenged because CMS and OIG are looking specifically for diagnoses that are not sufficiently backed by the record. CMS says RADV confirms whether diagnoses are supported in medical records, and OIG says a notable share of improper MA payments is driven mainly by unsupported diagnoses. 

What gets challenged most often

OIG’s 2025 Medicare Advantage audit language says some diagnoses are at higher risk for being miscoded. OIG’s current work plan says prior reviews have shown some diagnoses are more likely than others to be unsupported by medical record documentation. 

Why auditors challenge them

The challenge usually happens because the record does not show enough support, the diagnosis is more severe than the note supports, the capture path is weak, or the diagnosis appears only in sources OIG considers more vulnerable to misuse, such as isolated HRA/HRA-linked chart review pathways.