Underdosing of antithrombotic drugs, subsequent encounter

This code indicates that a patient experienced an adverse effect due to receiving less than the prescribed or recommended dose of an antithrombotic medication, and this is not the initial treatment for the condition. This underdosing event is impacting the patient's current care or condition during a follow-up visit.

Apply this code when a patient presents for ongoing management of a condition, and it is identified that their antithrombotic medication was underdosed, leading to a clinical consequence. This is appropriate for situations where the underdosing is being addressed during a subsequent encounter, such as a follow-up appointment for a thrombotic event that reoccurred due to insufficient medication.

• Always sequence this code after the code(s) for the specific condition being treated or the adverse effect caused by the underdosing.
• Ensure documentation clearly states that the underdosing occurred and that this is not the first time the patient is being seen for this issue.
• Distinguish from poisoning (T36-T50 with 5th or 6th character 1-4) where the drug was correctly administered but caused an adverse effect.