ICD 10 Coding Alert

You’ve had months to use the Z79.- (Long term (current) drug therapy) codes.

Pause and make sure that your use of these drug therapy codes is tip-top.

Revisit Z79.- Codes

The 2023 ICD-10-CM code set added a new code group: Z79.6- (Long term (current) use of immunomodulators and immunosuppressants). The code set features the following subdivisions:

• Z79.60 (Long term (current) use of unspecified immunomodulators and immunosuppressants)
• Z79.61 (… immunomodulator)
• Z79.62- (… immunosuppressant)
• Z79.63- (… chemotherapeutic agent)
• Z79.64 (… myelosuppressive agent)
• Z79.69 (… other immunomodulators and immunosuppressants)

Coding alert: ICD-10-CM 2023 also broke Z79.62- and Z79.63- down into more specific drug types, such as Z79.623 (… mammalian target of rapamycin (mTOR) inhibitor) and Z79.634 (… topoisomerase inhibitor). Many of these codes also provide inclusion terms that identify specific drugs. For example, you can use Z79.630 (… alkylating agent) for such chemotherapy drugs as chlorambucil, cisplatin, and cyclophosphamide.

Coding tip: AAPC’s 2023 ICD-10-CM Expert code book contains an appendix, A, that lists numerous drugs and connects them to their appropriate Z79 code.

Use Z Codes in These Situations

In general, you can assign these, or any Z code for that matter, “as appropriate to further explain the reasons for presenting for healthcare services, including transfers between healthcare facilities, or provide additional information relevant to a patient encounter,” according to ICD-10-CM Official Guideline I.B.19.d. Essentially, you’ll use Z codes as supporting details.

Define ‘Long-Term’ With ICD-10-CM

ICD-10-CM does not specify a time frame for assigning any code from Z79.-. However, you should “assign a code from Z79 if the patient is receiving a medication for an extended period as a prophylactic measure (such as for the prevention of deep vein thrombosis) or as treatment of a chronic condition (such as arthritis) or a disease requiring a lengthy course of treatment (such as cancer),” per guideline I.C.21.c.3.

Alternatively, the guideline also says you should not assign a code from Z79.- “for medication being administered for a brief period of time to treat an acute illness or injury (such as a course of antibiotics to treat acute bronchitis).”

In other words, you’ll assign a Z79.- code if the patient is taking a drug over an extended period of time (“long-term”) for a chronic condition, and the patient is taking the medication at the time of the encounter (“current”).

Use Z79.- Codes to Add Context

Even though ICD-10-CM does not require you to report Z79.- codes, there are several good reasons why you should.

Support MDM level: Z79.- codes can play an important role in helping to determine moderate and high medical decision making (MDM) levels of an office/outpatient evaluation and management (E/M) visit. That’s because prescription drug management is an example of moderate risk of morbidity from additional diagnostic testing or treatment, while drug therapy requiring intensive monitoring for toxicity is an example of high risk. So, the Z79.- codes can play a role in helping to justify the complexity of the MDM involved in the patient’s care.

For example, reporting a code such as one from Z79.63- may help support the highest-level E/M, but only when one of the two other MDM elements also supports that level. You’ll also need to ensure physician documentation is present to support the monitoring or toxicity of the drug reported with the ICD-10-CM code.

Support medical necessity for testing and treatment: “When patients require laboratory testing to ensure drug efficacy and safety, the claim reporting is better serviced with the addition of a specific Z79.- code that identifies the therapy the patient is receiving,” explains Carol Pohlig, BSN, RN, CPC, ACS, senior coding and education specialist for the University of Pennsylvania Department of Medicine, Hospital of the University of Pennsylvania. “Adding a diagnosis from this expanded category provides a better electronic explanation of these tests or treatments,” Pohlig adds.

Additionally, the codes provide more specificity than Z79.899 (Other long term (current) drug therapy), which you may have used prior to ICD-10-CM’s introduction of the Z79.6- codes to document long-term current use of drugs for treating a cancer patient. This means you’ll need to use them if and when Medicare adds these codes to their national coverage determination (NCD) and/or 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 Z79.899,” cautions Halee Garner, CPC, CPMA, CCA, certified coder for Digestive Health Partners in Asheville, North Carolina.