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AAOS Now

Published 3/1/2007
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Jennifer Bever, MS, FACHE

Using Modifier AS for surgical assist services

Nonphysician providers (NPPs) are becoming increasingly important in orthopaedic practices, leading to questions about how to correctly code and bill for the surgical assist services they provide. Although commercial rules for reporting surgical assist services can and do vary markedly, the Medicare rules apply across the country and are quite clear.

Medicare uses modifier AS to report nonphysician assistant-at-surgery services. When an NPP assists a surgeon, Medicare requires that the claim be submitted under the NPP’s name with his or her provider number (National Provider Identifier or NPI) and with modifier AS appended to the reported surgical code(s). Use of modifier AS to report assistant-at-surgery services by NPPs is a national Medicare policy and not subject to local payment policies. As such, NPP assistant-at-surgery claims billed to Medicare should always use modifier AS. Submission of NPP assist charges to Medicare with modifier 80 will result in claim denials.

Medicare recognizes physician assistants (PAs), nurse practitioners, and clinical nurse specialists as NPPs with independent billing rights. Additional clinicians, although skilled, are not recognized for payment by Medicare. These include registered nurse first assistant, certified surgical tech, and orthopaedic physician assistant (OPA or ortho tech). The OPA situation is perhaps the most confusing, due to the similarity in title with PAs. But because OPAs have not completed the requirements of a PA (undergraduate degree and additional graduate studies, plus state licensure and association certification), no claims should be submitted to Medicare for assistant-at-surgery claims for these alternate clinicians.

Practices should check with commercial plans as these additional clinicians may be eligible for reimbursement as an assistant at surgery depending on plan payment rules or employer benefit plans. Also check for state laws governing payment of clinicians. If reimbursement is available, inquire about required modifiers and claim format and obtain these directives in writing.

Ideally, all commercial plans would accept and process the AS modifier for assistant-at-surgery NPP claims. Some plans may request alternate modifiers. Commercial plans that do not accept the AS modifier sometimes require that NPP assistant-at-surgery claims must be submitted not only with the modifier 81 (or 80/82), but also under the physician’s name and number (as opposed to Medicare’s requirement of submitting the claim under the NPP’s name and number). This can result in confusion, however, and, in the worst-case scenario, the payer might pay the assistant claim and deny the primary surgeon’s claim as a duplicate. For this reason, widespread use of the AS modifier and independent credentialing of NPPs would be ideal.

Jennifer Bever, MS, FACHE, is a consultant with KarenZupko & Associates.