Oncology & Hematology Coding Alert

A patient arrives for an evaluation and management (E/M) visit following chemotherapy for metastatic squamous neck cancer. The reason for the visit states “throat pain from vomiting following chemotherapy.” Documentation confirms the patient received the chemotherapeutic agent prescribed, and it was administered per the physician’s order.

Code for Adverse Drug Effect

Codes in categories T36-T50 are combination codes that identify the substance the patient took, as well as the intent. Your code search begins at the Table of Drugs and Chemicals, and landing on the correct code hinges on you pinpointing the type of drug toxicity:

• Adverse effect: Problem that arises after taking a drug that has been correctly prescribed and properly administered
• Poisoning: Reaction to the improper use of a medication
• Underdosing: Taking less of a medication than is prescribed
• Toxic effect: Ingestion or contact with a harmful substance

“The key to coding from the Table of Drugs and Chemicals in ICD-10-CM is understanding the differences between these definitions, knowing the difference between adverse effect, poisoning, underdosing, and toxic effect,” says Barbara J. Cobuzzi, MBA, CPC, COC, CPC-P, CPC-I, CENTC, CPCO, CMCS, of CRN Healthcare in Tinton Falls, New Jersey. Based on these definitions, we can deduce that the patient is experiencing an adverse effect of the chemotherapeutic agent.

So, if you turn to the ICD-10-CM Table of Drugs and Chemicals, you can search under the terms “antineoplastic” or “cancer chemotherapy drug regimen” to find the correct set of codes. You will then select the code listed under “adverse effect” and refer to the Tabular List to verify the full code, which in this case is T45.1X5A (Adverse effect of antineoplastic and immunosuppressive drugs, initial encounter).

Remain vigilant: You do not want to use the code listed under “poisoning, accidental (unintentional).” While providers typically take precautions to lessen or eliminate common side effects, and since the provider prescribed the correct drug in the correct dosage, these side effects can be an expected course of chemotherapy treatment. If, on the other hand, the patient received a much greater dosage than the doctor had prescribed or the wrong substance was given, you could report code T45.1X1A (Poisoning by antineoplastic and immunosuppressive drugs, accidental (unintentional), initial encounter).

Code for the Condition

In order to code this scenario correctly, you need to have a firm grasp of the known side effects of chemotherapy. Since nausea and vomiting are typical side effects for patients being administered chemotherapy, you will take a different route of coding this situation than if the effects were unintended or unexpected. According to section I.C.19.e.5.a of the 2023 ICD-10-CM guidelines:

When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug (T36-T50). ... Examples of the nature of an adverse effect are tachycardia, delirium, gastrointestinal hemorrhaging, vomiting, hypokalemia, hepatitis, renal failure, or respiratory failure.

Based on this guideline, you should code the vomiting first, followed by the adverse effect of chemotherapy code. For emesis, you will report code R11.10 (Vomiting, unspecified) along with T45.1X5A.

Even though the throat pain is the underlying reason for the visit, the pharyngalgia is a result of the vomiting. ICD-10-CM guideline I.B.7 states that “if a causal condition is known, then the code for that condition should be sequenced as the principal or first-listed diagnosis.” Since throat pain is not always a typical symptom of vomiting, you may include R07.0 (Pain in throat) as a third and final diagnosis.

Code for Long-Term Drug Use if Appropriate

The 2023 ICD-10-CM code set expands your options in category Z79 (Long term (current) drug therapy). This code boost allows you to identify the type of chemotherapy being administered to the patient. If the specific drug is documented, you can now assign the appropriate code from the following:

• Z79.630 (Long term (current) use of alkylating agent) for chlorambucil, cisplatin, and cyclophosphamide
• Z79.631 (Long term (current) use of antimetabolite agent) for methotrexate, 5-fluorouracil, 6-mercaptopurine, and cytarabine
• Z79.632 (Long term (current) use of antitumor antibiotic) for bleomycin, doxorubicin, and mitomycin C
• Z79.633 (Long term (current) use of mitotic inhibitor) for paclitaxel, plant alkaloids, vinblastine, and vincristine
• Z79.634 (Long term (current) use of topoisomerase inhibitor) for etoposide, irinotecan, and topotecan

Code for the E/M Visit

Remember that the patient’s response to the chemotherapy treatment may require a visit with the physician or other qualified health care provider (QHP). Chemotherapy, and the cancer itself, could be enough to potentially bump an E/M service to 99215 (Office or other outpatient visit for the evaluation and management of an established patient … high level …) if the drug therapy required intensive monitoring for toxicity, as this could create a high level for the risk element of medical decision making (MDM). So, reporting a code such as Z79.630- may support the higher-level E/M. “Considering only the side effects and throat pain for an ongoing chemotherapeutic regimen, without additional contributing factors, the visit would likely fall into a moderate level of MDM if it was only directed toward the vomiting due to chemo. The E/M service level is entirely dependent on the documentation of the service,” says Leah Fuller, CPC, COC, with Pinnacle Enterprise Risk Consulting Services in Charlotte, NC.

Note: Be on the lookout for when the Centers for Medicare & Medicaid Services (CMS) adds these codes to the National Coverage Determination (NCD) and Local Coverage Determination (LCD) lists and articles. “Ordering lab work to monitor patients on these newly represented medications may not be covered if reported with Z79.8 or Z79.899,” cautions Halee Garner, CPC, CPMA, CCA, certified coder for Digestive Health Partners in Asheville, N.C.