Executive Summary

Multiplex polymerase chain reaction (PCR) panels have transformed GI infection diagnostics, offering fast, accurate, and potentially cost-effective testing. However, regulatory inconsistencies, coding limitations, and laboratory practices are impeding their full potential. Systemic reforms are needed to ensure equitable access and optimal utilization, ultimately improving patient outcomes.

Acute gastroenteritis is a leading cause of outpatient visits in the US, with viral pathogens like norovirus and rotavirus being the most common. While typically self-limiting, bacterial and parasitic infections—especially in vulnerable groups such as travelers, immunocompromised individuals, men who have sex with men (MSM), and persons experiencing homelessness—can be more severe and require targeted treatment.

Traditional diagnostic methods, including stool cultures and antigen tests, are limited by low sensitivity and long turnaround times. Syndromic multiplex PCR panels have emerged as an alternative, offering fast and simultaneous detection of multiple pathogens. These panels are now widely adopted, though cultures remain necessary for public health surveillance and antimicrobial susceptibility testing.

Multiplex PCR panels demonstrate high sensitivity and specificity, detecting significantly more pathogens—including mixed infections—than conventional methods. Their fast turnaround enables timely treatment, reduces unnecessary antimicrobial use, and improves infection control. Studies show benefits such as shorter hospital stays, reduced imaging and endoscopy needs, and improved antimicrobial stewardship (AMS). These panels are especially valuable in immunosuppressed patients and those with inflammatory bowel disease.

Despite their advantages, multiplex panels must be used judiciously. Guidelines recommend testing only in patients with severe, prolonged, or outbreak-related symptoms, and discourage use in hospitalized patients beyond three days unless C. difficile is suspected. Stewardship efforts span pre-analytic (e.g., specimen appropriateness), analytic (e.g., result reporting), and post-analytic phases to ensure optimal use and avoid over testing.

Reimbursement challenges remain a hindrance to broader adoption. Medicare’s Local Coverage Determinations (LCDs) vary widely, often limiting coverage for expanded panels unless specific criteria are met. These inconsistencies lead to provider confusion and may incentivize the use of smaller, less optimal panels. Additionally, ICD-10 coding lacks granularity to capture symptom severity or duration, complicating reimbursement and contributing to denials.

To address these challenges, the authors recommend harmonizing LCD criteria, updating ICD-10 codes to reflect clinical severity and duration, and refining guidelines to support evidence-based use of multiplex panels. Reimbursement should be based on clinical necessity rather than panel size limits. Full result reporting and improved coding practices would enhance diagnostic accuracy, reduce administrative burdens, and promote equitable access to advanced diagnostics.

Multiplex PCR panels have transformed GI infection diagnostics, offering rapid, accurate, and cost-effective testing. However, regulatory inconsistencies, coding limitations, and laboratory practices are impeding their full potential. Systemic reforms are needed to ensure equitable access and optimal utilization, ultimately improving patient outcomes.

Authors:

Giannoula S. Tansarli, MD, PhD¹, David R. Allen, PharmD², Ferric C. Fang, MD^{1, 3}

1. Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA, USA
2. bioMérieux, Market Access, Salt Lake City, UT, USA
3. Department of Microbiology, University of Washington School of Medicine, Seattle, WA, USA