Assigning ICD-10-CM Codes for Long Term Drug Therapy

ICD-10-CM has codes to report a patient’s continuous use of a prescribed drug for the long term management of a condition or prophylactic use.

The designation “long term” could mean different things to different people. The coding reference Basic ICD-10-CM and ICD-10-PCS Coding adds clarification to this designation. This publication states, “There is no official definition or time frame for long term. If a patient receives a drug on a regular basis and has multiple refills available for a prescription it is appropriate to document long term drug use.”

These codes are “status” Z codes. The information they report is important because it may affect the course of treatment or management of the patient.

These codes may be used to explain why certain diagnostic tests are being performed for a patient. For example, a patient taking Coumadin on a long term basis will need regular testing to ensure their PT/PTT times are at an acceptable level. Assignment of code Z79.01 Long term use of anticoagulants, assigned as a secondary code to Z51.81 Encounter for therapeutic drug level monitoring, indicates the reason the patient needs those diagnostic tests.

These codes may also be used to indicate the type of long term drug therapy that has been prescribed for a patient such as specifying the type of glucose management used by a diabetic patient as insulin, non-insulin injectables or oral medication.

Category Z79 Long Term (Current) Drug Therapy

In ICD-10-CM, codes to report continuous use of a prescribed drug are found in category Z79 Long term (current) drug therapy.

ICD-10-CM Subcategories of Long Term Drug Therapy Codes

Category Z79 is subdivided into eight categories based on drug classification.

• Z79.0 Long term (current) use of anticoagulants and antithrombotics/antiplatelets
• Z79.1 Long term (current) use of non-steroidal anti-inflammatories (NSAID)
• Z79.2 Long term (current) use of antibiotics
• Z79.3 Long term (current) use of hormonal contraceptives
• Z79.4 Long term (current) use of insulin
• Z79.5 Long term (current) use of steroids
• Z79.6 Long term (current) use of immunomodulators and immunosuppressants
• Z79.8 Other long term (current) drug therapy

These subcategories are further divided into more specific subcategories and then into codes for a specific drug or classification of drugs.

Example:

Subcategory Z79.5 reports long term use of drugs classified as steroids. This subcategory is further divided into two codes, one reporting long term use of inhaled steroids and one reporting long term use of systemic steroids.

Z79.5 Long term (current) use of steroids

Z79.51 Long term (current) use of inhaled steroids

Z79.52 Long term (current) use of systemic steroids

The coder is responsible for knowing which of these codes represents the medication the patient has been prescribed. If the patient uses Flovent to treat asthma the correct code is Z79.51 because Flovent is administered by inhalation. If the patient uses prednisone to treat ulcerative colitis the correct code is Z79.52 because the drug is distributed throughout the body (systemic).

ICD-10-CM Coding Guideline I.C.21.c.3

ICD-10-CM guideline I.C.21.c.3 includes instruction specific to the assignment of category Z79 codes.

Z79 Long-term (current) drug therapy

Codes from this category indicate a patient’s continuous use of a prescribed drug (including such things as aspirin therapy) for the long-term treatment of a condition or for prophylactic use. It is not for use for patients who have addictions to drugs. This subcategory is not for use of medications for detoxification or maintenance programs to prevent withdrawal symptoms (e.g., methadone maintenance for opiate dependence). Assign the appropriate code for the drug use, abuse, or dependence instead.

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). Do not assign a code from category 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).

The guideline explains that these codes:

• Report continuous use of a prescribed drug for
  • long-term treatment of a chronic condition (eg, diabetes)
  • prophylaxis against the occurrence of a condition (eg, blood clots)
  • treatment of a disease that is not chronic, but requires a lengthy course of treatment (eg, cancer) 

• Are not used to report addiction to drugs
• Do not report use of drugs for detoxification or maintenance programs or to prevent symptoms of withdrawal.
• Do not report use of drugs prescribed for a brief time or to treat an acute illness. (Per Coding Clinic this includes drugs prescribed on a PRN basis).

Medication Prescribed During a Patient Encounter

The direction provided in the ICD-10-CM coding guidelines does not specifically indicate at what point in a patient’s course of care assignment of a code from category Z79 should begin. It’s long been thought by many coders that the patient must have been taking the medication prior to the encounter being coded for long term drug therapy codes to be assigned and that no long term drug therapy codes are assigned if the drug was first prescribed during the encounter being coded.

Coding Clinic advice from second quarter of this year provides clarification on this point.

The question was posed to Coding Clinic, “…Would it be appropriate to assign a code from category Z79, Long-term (current) drug therapy, for newly prescribed medication based on the intended long-term use to manage a chronic condition?”

The response in Coding Clinic affirms that “…it would be appropriate to assign a code from category Z79, Long-term (current) drug therapy, when a patient is prescribed a medication that is intended to be taken on a long-term basis to control a chronic condition such as diabetes mellitus. Code assignment is not based on whether the medication is new for the patient, but rather the intended use of the medication for long-term drug therapy. However, if there is an indication that the medication is to be used for a brief period and not on a long-term basis, a code for long-term drug therapy would not be reported.”

In consideration of Coding Clinic’s advice, codes from category Z79 Long term (current) drug therapy may be assigned for any encounter where the patient has been prescribed medication for the long term management of a condition regardless of when the medication was prescribed.

Take Aways

• Long term drug therapy codes are used to report continuous use of prescribed medication
• Regular use of a prescribed medication with multiple refills available qualifies for reporting long term use of a drug
• Long term drug therapy codes are not used to report addiction to drugs or use of medication used to manage drug addiction or withdrawal
• Codes for long term drug therapy may be assigned anytime the patient has a prescription for and it taking the medication, even if the prescription was written during the encounter currently being coded.

On October 1, 2023, 15 new “Long Term (Current) Drug Therapy” codes were added to ICD-10-CM. At that time HIA released a list of the new codes with a list of drugs whose long term use is reported with each code and the diagnoses these drugs are used to treat. Click here to download the updated list. Keep in mind that the list is not all-inclusive or exhaustive.

References

• Basic ICD-10-CM and ICD-10-PCS Coding (Palkie and Walraven 2024, page 716)
• ICD-10-CM Official Guidelines for Coding and Reporting
• Coding Clinic for ICD-10-CM/PCS, Second Quarter 2024, Page 26
• Coding Clinic for ICD-10-CM/PCS, First Quarter 2021, Page 12
  
• https://www.micromedexsolutions.com/micromedex2/librarian/deeplinkaccess?source=deepLink&i

Since 1992, HIA has been the leading provider of compliance audits, coding support services and clinical documentation audit services for hospitals, ambulatory surgery centers, physician groups and other healthcare entities. HIA offers PRN support as well as total outsource support.

The information contained in this coding advice is valid at the time of posting. Viewers are encouraged to research subsequent official guidance in the areas associated with the topic as they can change rapidly.