I won't say anything specific about UnitedHealthcare or take a position on their actions but will comment generally about Medicare Advantage plans. The standard defense is that many of the diagnosis codes are highly subjective and depend on clinician judgment more than objective lab tests. Different doctors might reach different conclusions but that's normal in medicine and doesn't necessarily indicate fraud or malpractice. Health plans will also claim that adding formal diagnosis codes for all of a patient's conditions to their chart helps to get them the best care.