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MA84 Remark Code: Not an Approved NETT Study Participant

MA84 means the claim identified the patient as a National Emphysema Treatment Trial participant, but the payer's records show the patient either is not a participant or is not yet approved for that phase. The official text directs you to Johns Hopkins University, the study coordinator.

Quick facts

Code
MA84 (RARC MA84)
Status
Active In use since January 1, 1997.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The service was not paid under the study because participation could not be confirmed. The provider resolves it before any patient billing.
Official description
Patient identified as participating in the National Emphysema Treatment Trial but our records indicate that this patient is either not a participant, or has not yet been approved for this phase of the study. Contact Johns Hopkins University, the study coordinator, to resolve if there was a discrepancy.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What MA84 means

MA84 is a narrow, study-specific Medicare remark. It applies when a claim identifies the patient as a participant in the National Emphysema Treatment Trial (NETT), a study of lung volume reduction surgery, but the payer’s records say the patient is not a participant or has not been approved for the phase of the study billed.

Because payment for study services depended on documented enrollment, the claim cannot be paid as submitted.

Common causes

  • The patient’s enrollment or phase approval was not yet recorded when the claim was processed.
  • The patient was never enrolled, but the claim was coded as a study service.
  • Patient identifiers on the claim did not match the study records.

What to do

  1. Check the patient’s study status with your research team.
  2. Contact the study coordinator named in the official text, Johns Hopkins University, if records conflict.
  3. Correct the claim if the service was mistakenly coded as part of the study, and bill it under standard coverage rules.
  4. Resubmit once participation is confirmed, following the payer’s corrected-claim process.

Research-related billing problems overlap with authorization issues; see authorization and referral denials for general prevention practices.

Codes that may appear with MA84

  • CO-96 (Non-covered charge(s).): A non-covered charge, with MA84 explaining that study participation was not verified.
  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Information on the claim, such as study identification, did not match payer records.
  • MA50 (Missing/incomplete/invalid Investigational Device Exemption number or Clinical Trial number.): A missing or invalid investigational device exemption or clinical trial number.
  • MA97 (Missing/incomplete/invalid Medicare Managed Care Demonstration contract number or clinical trial registry number.): A missing managed care demonstration contract number or clinical trial registry number.

MA84 FAQ

What was the National Emphysema Treatment Trial?

It was a Medicare-supported clinical study of lung volume reduction surgery for patients with emphysema. MA84 is tied specifically to that study.

Who resolves a discrepancy?

The official text says to contact Johns Hopkins University, the study coordinator, to resolve any discrepancy in the patient's participation.

Will I see MA84 today?

It is rare because it applies to one specific study. If it appears, confirm the claim was not coded as a study service by mistake.