PR-55: Experimental / Investigational Procedure

What Does PR-55 Mean?

PR 55 shifts financial responsibility to the patient because their benefit plan explicitly excludes experimental, investigational, or unproven treatments. The patient may have been unaware of this exclusion at the time of enrollment. For Medicare patients enrolled in qualifying clinical trials, separate rules may provide some coverage for routine costs of care associated with the trial.

CARC 55 shows up when the payer has decided that the service you billed is experimental, investigational, or does not have sufficient clinical evidence to meet their coverage standards. This is a coverage denial based on the payer's medical policy, not on whether the service was coded correctly or documented properly. The payer is saying that even with perfect documentation, they do not consider this service proven enough to cover.

This denial code frequently applies to newer medical technologies, off-label drug uses, emerging surgical techniques, and treatments that have Category III CPT codes (temporary codes for emerging technology). Each payer maintains their own medical policy that defines what they consider experimental. A procedure might be covered by one commercial plan and denied as experimental by another based on their respective evidence review processes. Medicare uses NCDs and LCDs to make these determinations, while commercial payers typically rely on internal medical policy committees and technology assessment organizations.

The distinction between CARC 55 (experimental/investigational) and CARC 56 (not effective) is subtle but important. CARC 55 applies when the payer says the treatment lacks enough evidence to determine if it works. CARC 56 applies when the payer has reviewed the evidence and concluded the treatment does not work. The appeal strategy differs: for CARC 55, you need to demonstrate that sufficient evidence exists; for CARC 56, you need to prove the evidence shows the treatment is effective.

Common Causes

How to Resolve

Challenge the payer's experimental classification by presenting peer-reviewed clinical evidence, FDA approval status, and professional society endorsements.

1. Confirm the plan exclusion Verify with the payer that the patient's plan excludes the treatment and that the experimental classification is current. Payer policies change, and what was experimental last year may now be covered.
2. Inform the patient Explain the denial to the patient, including why the payer classified the treatment as experimental. Provide information about their appeal rights and any external review options.
3. Explore clinical trial coverage For Medicare patients, check whether the patient is enrolled in a qualifying clinical trial that would provide coverage for routine costs. For commercial patients, check if the plan has a clinical trial coverage provision.

How to Prevent PR-55

• Inform patients before rendering services if the treatment may be classified as experimental by their payer.
• Obtain signed financial responsibility forms before providing potentially non-covered experimental treatments.
• Help patients explore clinical trial enrollment options that may provide coverage.

General Prevention

• Inform patients before rendering services if the treatment may be classified as experimental by their insurance.
• Obtain signed ABNs or financial responsibility forms before providing potentially non-covered treatments.
• Help patients explore clinical trial enrollment options that may provide coverage for experimental treatments.

Also Filed As

The same CARC 55 may appear with different Group Codes:

Related Denial Codes