Long-Term Medication Use ICD-10-CM codes

A medication refill visit is coded to the condition being treated, not to the drug. Hypertension gets I10, type 2 diabetes gets E11.9, and so on, with the Z79 code added as a secondary diagnosis to show the patient is on long-term therapy: Z79.4 for insulin, Z79.84 for oral hypoglycemics, Z79.85 for injectable non-insulin antidiabetics such as GLP-1 agonists, Z79.01 for anticoagulants, Z79.52 for systemic steroids, Z79.891 for opioids, and Z79.899 for any drug without its own code. Z79 codes are never first-listed when the treated condition is known. Z76.0 (encounter for issue of repeat prescription) is the only code for a refill-only encounter where no condition is evaluated, and it should be rare in a physician office because such a visit usually does not support an E/M service.

Per section I.C.21.c.3, Z79 applies when a patient takes a drug for an extended period as prophylaxis, as treatment for a chronic condition, or to prevent recurrence. It does not apply to a short course for an acute illness (a 10-day antibiotic is not Z79.2), and it does not apply to methadone or buprenorphine maintenance for opioid dependence, which is captured by the F11.2x code alone. For diabetes, the guidelines now instruct that a patient on both insulin and an oral agent gets both Z79.4 and Z79.84, and a patient on insulin plus an injectable non-insulin drug gets Z79.4 and Z79.85.

Hormone replacement is Z79.890, added as a secondary code to the reason for therapy: N95.1 for symptomatic menopause, Z78.0 for the asymptomatic menopausal state, or a hypogonadism code. Long-term hormonal contraceptives are Z79.3 and are coded with the Z30.4x surveillance encounter, and the cancer-related endocrine agents have their own codes: Z79.810 for tamoxifen and other SERMs, Z79.811 for aromatase inhibitors. Immunosuppressant and biologic use is now subdivided in Z79.6x (Z79.620 biologics, Z79.621 calcineurin inhibitors, Z79.622 JAK inhibitors) and maintenance oral chemotherapy in Z79.63x.

When a drug level or safety lab is the reason for the visit, sequence Z51.81 (therapeutic drug level monitoring) first, then the Z79 code, then the condition. Underdosing or noncompliance with the medication regimen is reported with Z91.12x, Z91.13x, or Z91.14x alongside the condition that worsened, and the underdosing T code with 6th character 6 when the drug is identified.