Why would the MAO-004 report list a diagnosis as disallowed?

The MAO-004 report will identify diagnoses as “allowed” or “disallowed” to indicate whether or not they are risk adjustment eligible. If diagnoses pass the CMS filtering logic, they are “allowed.” Allowed diagnoses are considered eligible for risk adjustment since these are the diagnoses that are run through the model when calculating risk scores. Not all diagnoses that are run through the model will be included in the risk score calculation, since not all diagnoses map to the Hierarchical Condition Category (HCC) in the model. Please refer to the December 20, 2017 CMS Health Plan Management System (HPMS) Memo with subject line, “Phase III Version 3 MAO-004 Report Release Date and Announcement Regarding Final Encounter Data Deadlines for Payment Years 2016-17.