HCPCS Code M1158: Deleted code for History of Immunocompromising Conditions Prior to or During the Measurement Period

## **HCPCS code M1158 documentation requirements** HCPCS Code M1158 was a deleted code related to a patient’s history of immunocompromising conditions, and documentation requirements for this code were tied to Medicare administrative guidelines. Specifically, Medicare Administrative Contractors (MACs) such as Novitas and FCSO required supporting documentation for certain pathology and laboratory claims, including those involving codes like M1158. The documentation needed typically would include evidence or medical records confirming the patient’s immunocompromised status during the measurement period, or details from a patient reported outcome tool or functional status measurement (e.g., Oswestry Disability Index or visual analog scale) obtained utilizing standard protocols. This could also involve noting when a patient administered vaccine, a patient declined care, or a patient self-discharged early. In some cases, patient reasons, medical reasons, or a patient's allergy had to be recorded if the treatment episode ended prematurely or if an impossible status applied. Documentation also included information about immunosuppressive therapy, active chemotherapy, or the use of intravenous injection drugs, especially when patients faced degenerative or neurological conditions. In inpatient and surgical settings, details about additional spine procedures performed on the same date as the treatment or any specific medical events, such as invasive mechanical ventilation, had to be included. Since M1158 is now a deleted code, contractors use Integrated Outpatient Code Editor (I/OCE) specifications to enforce edits and validate claims with relevant documentation when applicable.

## **M1158 billing requirements** HCPCS code M1158 billing requirements were governed by CMS and Medicare Administrative Contractors (MACs) policies, including those of Novitas and FCSO. These MACs required supporting documentation for certain pathology and laboratory claims involving this code. The claims must be submitted in compliance with the Integrated Outpatient Code Editor (I/OCE) specifications, which route institutional outpatient claims and enforce billing rules. Key billing requirements included are: - Claims with M1158 had to be supported by appropriate documentation verifying the patient's history of immunocompromising conditions. - Medicare contractors applied the I/OCE edits to validate claims involving this code, rejecting those that failed to meet documentation or coding criteria. - Remittance Advice Remark Codes (RARC) would be issued for claim denials or adjustments when edits were triggered. - Starting January 1, 2024, and updates through 2025, the I/OCE specifications outlined the mandatory compliance standards for outpatient billing, with CMS making ongoing updates to reflect deleted or revised codes like M1158. - Since M1158 is a deleted code, billing with this code is no longer valid and may result in claim denials if submitted. Providers must ensure they use current, valid codes and comply with documentation and CPT codes or other coding guidelines provided by MACs and CMS.

## **Other relevant codes** Other relevant codes related to HCPCS code M1158 (which pertained to patients with immunocompromising conditions) would primarily include codes for immunosuppressive therapy, immune globulin injections, and other treatment and prophylaxis codes for immunocompromised patients. Some examples of these relevant HCPCS level II codes for 2025 include: - **J7514**: Mycophenolate mofetil (immunosuppressive drug) - **J1552**: Immune globulin injection - **Q0224**: Injection, pemivibart, for pre-exposure prophylaxis in moderately to severely immunocompromised patients