What do the terms "primary" and "secondary" indicate in a set of ICD-10-CM codes?

The terms "primary" and "secondary" in the context of ICD-10-CM codes indicate a hierarchy of conditions. The primary diagnosis is the main condition or reason for a patient's visit or hospitalization. This is the diagnosis that is primarily responsible for the patient's care. The secondary diagnosis, on the other hand, refers to additional conditions that may be present and affect the patient's treatment or management but are not the main reason for the encounter.

Understanding this hierarchy is crucial for accurate coding and ensures that the healthcare provider's documentation reflects the complexity of the patient's condition. This helps in proper billing and reimbursement as well as in compiling health statistics and research data. The distinct roles of primary and secondary codes also facilitate effective communication among providers, payers, and public health entities regarding patient care and outcomes.