Undrdose of immune checkpoint inhibtr/immunostim drugs, subs

This code indicates that a patient is experiencing adverse effects or complications due to receiving an insufficient dose of immune checkpoint inhibitors or other immunostimulant medications. This underdosing is occurring during a follow-up visit, after the initial treatment or diagnosis of the underdosing event. The underdosing may lead to suboptimal therapeutic response or disease progression.

Apply this code when documentation clearly states that a patient's current condition is a direct result of receiving less than the prescribed amount of immune checkpoint inhibitors (e.g., pembrolizumab, nivolumab) or other immunostimulant drugs. This is appropriate for subsequent encounters where the underdosing is still being managed or its effects are being addressed. It should be used when the patient is seen for ongoing care related to the underdosing, not the initial discovery.

• Ensure the medical record explicitly states "underdosing" and identifies the drug class as immune checkpoint inhibitors or immunostimulants.
• Verify that the encounter is a "subsequent encounter," meaning it's not the first time the underdosing issue is being addressed.
• Always code the specific adverse effect or complication resulting from the underdosing first, followed by this underdosing code.