From the Guidelines
Sensitivity and Specificity of Procalcitonin (PCT) in Diagnosing Neonatal Sepsis
The sensitivity and specificity of procalcitonin (PCT) in diagnosing sepsis have been reported to be 0.80 (95% CI, 0.69–0.87) and 0.77 (95% CI, 0.60–0.88), respectively, in adult patients 1.
- Key points about PCT include:
- PCT is a precursor hormone of calcitonin produced by the parafollicular cells of the thyroid gland and neuroendocrine cells of the lung and the intestine 1.
- PCT begins to rise four hours after exposure to bacteria, reaching a maximum level after six to eight hours 1.
- Serum levels of PCT are associated with the severity of the infection, and decrease rapidly after antibiotic treatment 1.
- However, it's essential to note that the provided evidence does not specifically address neonatal sepsis, and the studies mentioned are focused on adult patients 1.
- In adult patients, a systematic review and meta-analysis found that PCT had a higher diagnostic accuracy and specificity compared to C-reactive protein (CRP) for diagnosing sepsis 1.
- The optimal cutoff values for PCT in diagnosing sepsis are not well established, but a level of less than 0.5 µg/L or a decrease of greater than or equal to 80% from peak levels may guide antibiotic discontinuation once patients stabilize 1.
- It's crucial to consider that decisions on initiating, altering, or discontinuing antimicrobial therapy should not be made solely based on changes in PCT or CRP levels, but rather as part of a comprehensive clinical evaluation 1.
From the Research
Sensitivity and Specificity of Procalcitonin in Diagnosing Neonatal Sepsis
- The sensitivity and specificity of procalcitonin (PCT) in diagnosing neonatal sepsis vary across different studies, with reported sensitivity ranging from 67% to 100% and specificity ranging from 17% to 95.5% 2, 3, 4, 5.
- A study found that PCT was highly sensitive (87% to 100%) at a cut-off value of 0.5 ng/mL, although specificity varied greatly across all cut-off values reviewed 2.
- Another study reported that at a PCT cut-off of 1.1 ng/mL, the sensitivity and specificity were 78.6% and 81.2%, respectively, for early-onset neonatal sepsis (EONS) 3.
- A study also found that at a PCT cut-off of 1.5 ng/mL, the sensitivity and specificity were 92.9% and 85.2%, respectively, for the diagnosis of neonatal infection 4.
- A secondary analysis of the Neonatal Procalcitonin Intervention Study reported that a PCT cutoff value of 2.8 ng/L provided a sensitivity of 100% for discriminating no sepsis vs proven sepsis within 36 hours 5.
Optimal Cut-off Values for Procalcitonin
- The optimal cut-off values for PCT in diagnosing neonatal sepsis are not well established, with different studies reporting different cut-off values 2, 3, 4, 5.
- A study suggested that PCT cut-off values may differ in preterm sepsis subgroups, with optimal cut-off levels of 1.1 ng/mL for EONS and 5.2 ng/mL for late-onset neonatal sepsis (LONS) 3.
- Another study reported that a PCT cut-off value of 1.36 ng/mL provided a sensitivity of 90.8% and specificity of 83.4% for proven sepsis 3.
Comparison with Other Biomarkers
- PCT has been compared to other biomarkers, such as C-reactive protein (CRP) and white blood count (WBC), in diagnosing neonatal sepsis 3, 4, 5.
- A study found that PCT and CRP had similar diagnostic performances, but were more efficacious than WBC in diagnosing neonatal sepsis 3.
- Another study reported that serial measurements of CRP and PCT within 36 hours after the start of empiric antibiotic therapy can exclude the presence of neonatal EOS with a high probability 5.