The secondary diagnosis refers to a coexisting condition that might exist at the time of patient admission. This condition might evolve over the course of the patient’s stay, or it might be cause for further treatment. Like primary diagnoses, secondary diagnoses are a key component of medical claims and provider billing.
Secondary diagnoses are paired with corresponding billing code sets (e.g. ICD-10 or DRG) and sent to healthcare payers in the form of a medical claim. This process is how providers receive reimbursement for healthcare services.