Z79.623Long term (current) use of mammalian target of rapamycin (mTOR) inhibitor

Z79.623 is the ICD-10-CM diagnosis code for long term (current) use of mammalian target of rapamycin (mTOR) inhibitor. It belongs to category Z79 (long term (current) drug therapy), block Z77-Z99 (persons with potential health hazards related to family and personal history and certain conditions influencing health status) and chapter 21 (factors influencing health status and contact with health services). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within Z79.62 (long term (current) use of immunosuppressant), Z79.623 is specifically for long term (current) use of mammalian target of rapamycin (mTOR) inhibitor. Related codes cover immunosuppressive biologic (Z79.620), calcineurin inhibitor (Z79.621), Janus kinase inhibitor (Z79.622) and inhibitors of nucleotide synthesis (Z79.624).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 949 (Aftercare with CC/MCC, relative weight 1.123) and DRG 950 (Aftercare without CC/MCC, relative weight 0.7664), in MDC 23 (Factors Influencing Health Status and Other Contacts with Health Services), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.

It is exempt from present-on-admission (POA) reporting, so no POA indicator is required.

It was added in FY2023, effective October 1, 2022.