New AACC Procalcitonin Testing Guidance to Improve Care for Patients with Bacterial Infections

Although procalcitonin tests have been employed in Europe for years, they were only introduced in the U.S. in 2017 when the FDA approved their use for guiding antibiotic treatment and predicting the likelihood of death within 28 days for sepsis patients. Given their recent arrival in the U.S., there remains uncertainty about the appropriate use of these tests, which are sometimes ordered in clinically inapplicable situations. To address this issue, new guidance offers a comprehensive analysis of procalcitonin research and its limitations, aiming to improve testing and treatment practices.

The American Association for Clinical Chemistry (AACC, Washington, DC, USA) has released expert guidance on procalcitonin testing, a blood marker used to detect severe bacterial infections and sepsis. This guidance aims to provide clarity for clinicians and laboratory professionals, enhancing the treatment of critically ill patients and those with specific lower respiratory infections. The document tackles key questions related to procalcitonin usage in managing adult, pediatric, and newborn patients with suspected sepsis and/or bacterial infections, especially those affecting the lower respiratory tract. It also examines the evidence for using these tests to inform antimicrobial treatment decisions and predict patient outcomes.

There is strong evidence supporting procalcitonin testing in guiding clinicians on when to discontinue antibiotic treatment in critically ill patients and those with certain lower respiratory tract infections. The AACC guidance suggests incorporating procalcitonin testing into comprehensive antimicrobial stewardship efforts, involving multidisciplinary teams. Some studies indicate that procalcitonin levels can also help determine when to stop antibiotics in newborns and pediatric patients with suspected sepsis who exhibit clinical improvement. However, the guidance authors believe these studies are insufficient in size to establish standard levels applicable across pediatric populations, given that procalcitonin reference intervals were established for adults. Consequently, if procalcitonin testing is used for these groups, it is important to define pediatric reference intervals or interpretive criteria.

Despite the FDA's approval of procalcitonin tests for predicting 28-day mortality risk in sepsis patients, the guidance does not recommend their routine use for this purpose. This is due to inconsistent procalcitonin cut-offs and clearance parameters, as well as a lack of substantial evidence demonstrating the benefit of estimating 28-day mortality risk for patients with sepsis and lower respiratory tract infections.

"Improved outcomes from [procalcitonin] implementation are more likely to be realized when the test is used in conjunction with antimicrobial stewardship programs, institutional interpretive algorithms, and clinical decision support tools," said the guidance document authors Drs. Allison B. Chambliss, Khushbu Patel, Jessica M. Colón-Franco, Joshua Hayden, Sophie E. Katz, Emi Minejima, and Alison Woodworth. "Successful implementation of clinical [procalcitonin] requires a multidisciplinary effort among laboratorians, pharmacists, and infectious disease providers."