What is the diagnostic accuracy of procalcitonin (PCT) for sepsis?

From the Guidelines

Procalcitonin has a moderate diagnostic accuracy for sepsis, with a sensitivity of 0.80 (95% CI, 0.69–0.87) and specificity of 0.77 (95% CI, 0.60–0.88) at commonly used cutoff values, as reported in a recent systematic review and meta-analysis 1. The diagnostic accuracy of procalcitonin for sepsis is influenced by various factors, including the cutoff value used, the population being studied, and the presence of other inflammatory conditions. Some key points to consider when using procalcitonin for sepsis diagnosis include:

• Procalcitonin levels can be elevated in conditions other than sepsis, such as trauma, surgery, and certain cancers 1.
• Serial measurements of procalcitonin can provide more valuable information than single values, as they can help identify trends and patterns in the patient's condition 1.
• Procalcitonin should not be used as the sole diagnostic marker for sepsis, but rather as part of a comprehensive clinical assessment that includes other biomarkers, clinical findings, and microbiological data 1.
• The use of procalcitonin-guided antibiotic stewardship has been shown to reduce antibiotic exposure and improve patient outcomes in certain populations, such as critically ill patients with suspected sepsis 1. Overall, procalcitonin can be a useful tool in the diagnosis and management of sepsis, but its use should be guided by a thorough understanding of its limitations and potential biases, as well as the individual patient's clinical context. Some of the key evidence supporting the use of procalcitonin in sepsis diagnosis and management includes:
• A systematic review and meta-analysis of 9 studies involving 495 patients in the sepsis and 873 in the nonsepsis groups, which found that procalcitonin had a moderate diagnostic accuracy for sepsis, with an area under the summary receiver operator characteristic (SROC) curve of 0.85 (95% CI, 0.82–0.88) 1.
• A meta-analysis of 11 RCTs involving 4,482 patients, which found that procalcitonin-guided antibiotic treatment in ICU patients with infection and sepsis resulted in improved survival and lower antibiotic treatment duration 1.
• A study of 16 studies and greater than 5000 patients, which found that procalcitonin-guided antibiotic discontinuation appeared to decrease antibiotic utilization by 1 day and improve mortality, although the evidence was considered low-certainty due to the substantial risk of bias, indirectness of effect, and unknown application of antibiotic stewardship programs in control arms 1.

From the Research

Diagnostic Accuracy of Procalcitonin for Sepsis

• The diagnostic accuracy of procalcitonin for sepsis has been evaluated in several studies, with varying results 2, 3, 4.
• A systematic review and meta-analysis published in 2013 found that procalcitonin had a mean sensitivity of 0.77 and specificity of 0.79 for diagnosing sepsis in critically ill patients 2.
• Another study published in 2007 found that the diagnostic performance of procalcitonin was low, with a mean sensitivity and specificity of 71% and an area under the summary receiver operator characteristic curve of 0.78 3.
• A more recent meta-analysis published in 2019 found that procalcitonin had a higher diagnostic accuracy than C-reactive protein for sepsis, with an area under the summary receiver operator characteristic curve of 0.85 and a sensitivity and specificity of 0.80 and 0.77, respectively 4.
• However, a study published in 2024 found that the sensitivity and specificity of procalcitonin in diagnosing bacterial sepsis in neonates varied greatly across different cut-off values, with a cut-off value of 0.5 ng/mL being highly sensitive but having variable specificity 5.

Comparison of Procalcitonin with Other Biomarkers

• Procalcitonin has been compared to C-reactive protein in several studies, with procalcitonin generally showing higher diagnostic accuracy for sepsis 4.
• However, the diagnostic accuracy of procalcitonin can be influenced by various factors, such as the cut-off value used and the population being studied 5.

Clinical Implications

• The use of procalcitonin as a diagnostic marker for sepsis has been recommended in several guidelines, but its clinical utility is still a topic of debate 2, 3.
• Procalcitonin may be useful in guiding antibiotic therapy and reducing unnecessary antibiotic use, but its use should be interpreted in the context of clinical judgment and other diagnostic tests 4.