Potential Overpayment Patterns: Non-Physician Assistant at Surgery

by Steve Nesnidal, MD, CPC, AHFI
Aug 15, 2024, 08:46 AM

A non-physician assistant at surgery--physician's assistant (PA), nurse practitioner (NP), or clinical nurse specialist (CNS)--actively assists the surgeon in charge of performing certain surgical procedures. An assistant at surgery must be a trained professional who is able to participate in and actively assist the surgeon in completing the operation safely and expeditiously by helping to provide adequate exposure in the operating field, at times maintaining hemostasis, cutting suture materials, clamping and ligating bleeding vessels, visualizing anatomic structures during a surgical operation and, in selected instances, performing designated parts of a procedure. For a non-physician assistant at surgery, the provider must append modifier “AS” to the procedure code when billing.

The Centers for Medicare & Medicaid Services (CMS) assigns indicators for Assistant at Surgery for each code listed on the Medicare Physician Fee Schedule (MPFS) to indicate which procedures are approved for assistants at surgery. Most Commercial health plans, including the major national carriers, follow these same CMS guidelines for assistants at surgery. Procedures with an indicator of “2” on the MPFS have no payment restrictions for assistants at surgery, therefore assistant at surgery is approved.

When an assistant at surgery service is provided by a non-physician provider, two reductions in the allowed charge are actually required. For all services by non-physician providers, Medicare allows only 85 percent of the physician provider’s MPFS amount. The non-physician provider must submit claims with their own NPI to be paid, which results in the first reduction. Assisting at surgery by another physician, the provider is allowed 16 percent of the surgeon’s MPFS amount. Assisting at surgery by a non-physician provider , appropriately billed with the “AS” modifier, results in the second reduction occurring, with the non-physician provider being allowed 13.6% of the surgeon’s MPFS amount (85% non-physician provider reduction on the 16% assistant at surgery reduction)^1,2.

The non-physician provider must bill with their own NPI and bill the modifier “AS” to activate the appropriate reductions. When a non-physician provider fails to use their own NPI, this can bypass the first reimbursement reduction but would be caught by the Context⁴ Payment Integrity system as an incorrect billing. Failure to append modifier “AS”, to identify the service performed as assistant at surgery, can bypass the second reimbursement reduction, but again would be caught by the Context⁴ Payment Integrity system as an incorrect billing. When a non-physician provider assisted at surgery but submits a claim using the surgeon’s NPI and also fails to add an “AS” modifier, the result can lead to reimbursement at 100 percent of the fee schedule instead of 13.6 percent.

Under the Medicare Recovery Audit Program, CMS has recently approved the audit topic of 0222-Non-Physician Billed Without Correct Assistant at Surgery Modifier: Incorrect Coding for the Recovery Audit Contractors (RAC). Assistant at surgery claims billed by non-physician practitioners without modifier “AS” will be corrected and the claim will be repriced.³From the past OIG Audit Report titled “Medicare Improperly Paid Physicians for Co-Surgery and Assistant-at-Surgery Services That Were Billed Without the Appropriate Payment Modifiers” released in November of 2022, we already know significant healthcare resources are involved. In the OIG’s review of just 100 statistically sampled surgical services claims, 14 of those claims were found to have been incorrectly billed without an assistant at surgery modifier.

Most Commercial payers follow CMS’ policies on non-physician provider and assistant at surgery^4,5reductions, so this issue could also cause significant overpayment patterns that impact commercial plans. Health Plans must be able to detect assistant at surgery claims submitted without “AS” modifier for non-physician providers to avoid overpayments. The Context⁴ Payment Integrity solution includes several edits that capture inconsistencies on assistant at surgery claims. Our Context⁴ Reference-based Pricing solution will properly calculate these reductions when pricing with Medicare RBP. For more information about Context⁴ Healthcare’s Payment Integrity and Reference-based Pricing solutions, visit our webpage here:

https://www.context4healthcare.com/health-industries/payers

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