Agreement Between Two Procalcitonin Assays in Hospitalized Children

Association Between Procalcitonin and Antibiotics in Children With Community-Acquired Pneumonia

OBJECTIVE

To determine whether empirical antibiotic initiation and selection for children with pneumonia was associated with procalcitonin (PCT) levels when results were blinded to clinicians.

METHODS

We enrolled children <18 years with radiographically confirmed pneumonia at 2 children's hospitals from 2014 to 2019. Blood for PCT was collected at enrollment (blinded to clinicians). We modeled associations between PCT and (1) antibiotic initiation and (2) antibiotic selection (narrow versus broad-spectrum) using multivariable logistic regression models. To quantify potential stewardship opportunities, we calculated proportions of noncritically ill children receiving antibiotics who also had a low likelihood of bacterial etiology (PCT <0.25 ng/mL) and those receiving broad-spectrum therapy, regardless of PCT level.

RESULTS

We enrolled 488 children (median PCT, 0.37 ng/mL; interquartile range [IQR], 0.11-2.38); 85 (17%) received no antibiotics (median PCT, 0.32; IQR, 0.09-1.33). Among the 403 children receiving antibiotics, 95 (24%) received narrow-spectrum therapy (median PCT, 0.24; IQR, 0.08-2.52) and 308 (76%) received broad-spectrum (median PCT, 0.46; IQR, 0.12-2.83). In adjusted analyses, PCT values were not associated with antibiotic initiation (odds ratio [OR], 1.02, 95% confidence interval [CI], 0.97%-1.06%) or empirical antibiotic selection (OR 1.07; 95% CI, 0.97%-1.17%). Of those with noncritical illness, 246 (69%) were identified as potential targets for antibiotic stewardship interventions.

CONCLUSION

Neither antibiotic initiation nor empirical antibiotic selection were associated with PCT values. Whereas other factors may inform antibiotic treatment decisions, the observed discordance between objective likelihood of bacterial etiology and antibiotic use suggests important opportunities for stewardship.

Harmonization status of procalcitonin measurements: what do comparison studies and EQA schemes tell us?

Sepsis represents a global health priority because of its high mortality and morbidity. The key to improving prognosis remains an early diagnosis to initiate appropriate antibiotic treatment. Procalcitonin (PCT) is a recognized biomarker for the early indication of bacterial infections and a valuable tool to guide and individualize antibiotic treatment. To meet the increasing demand for PCT testing, numerous PCT immunoassays have been developed and commercialized, but results have been questioned. Many comparison studies have been carried out to evaluate analytical performance and comparability of results provided by the different commercially available immunoassays for PCT, but results are conflicting. External Quality Assessment Schemes (EQAS) for PCT constitute another way to evaluate results comparability. However, when making this comparison, it must be taken into account that the variety of EQA materials consist of different matrices, the commutability of which has not yet been investigated. The present study gathers results from all published comparison studies and results from 137 EQAS surveys to describe the current state-of-the-art harmonization of PCT results. Comparison studies globally highlight a significant variability of measurement results that nonetheless seem to have a moderate impact on medical decision-making. For their part, EQAS for PCT provides highly discrepant estimates of the interlaboratory CV. Due to differences in commutability of the EQA materials, the results from different peer groups could not be compared. To improve the informative value of the EQA data, the existing limitations such as non-harmonized conditions and suboptimal and/or unknown commutability of the EQA materials have to be overcome. The study highlights the need for commutable reference materials that could be used to properly evaluate result comparability and possibly standardize calibration, if necessary. Such an initiative would further improve the safe use of PCT in clinical routine.

Pneumonia Severity in Children: Utility of Procalcitonin in Risk Stratification

OBJECTIVES

To determine if serum procalcitonin, an indicator of bacterial etiology in pneumonia in all ages and a predictor of severe pneumonia in adults, is associated with disease severity in children with community-acquired pneumonia.

METHODS

We prospectively enrolled children 2 months to <18 years with clinical and radiographic pneumonia at 2 children's hospitals (2014-2019). Procalcitonin samples were obtained at presentation. An ordinal outcome scale of pneumonia severity was defined: very severe (intubation, shock, or death), severe (intensive care admission without very severe features and/or high-flow nasal cannula), moderate (hospitalization without severe or very severe features), and mild (discharge). Hospital length of stay (LOS) was also examined. Ordinal logistic regression was used to model associations between procalcitonin and outcomes. We estimated adjusted odds ratios (aORs) for a variety of cut points of procalcitonin ranging from 0.25 to 3.5 ng/mL.

RESULTS

The study included 488 children with pneumonia; 30 (6%) were classified as very severe, 106 (22%) as severe, 327 (67%) as moderate, and 25 (5%) as mild. Median procalcitonin in the very severe group was 5.06 (interquartile range [IQR] 0.90-16.83), 0.38 (IQR 0.11-2.11) in the severe group, 0.29 (IQR 0.09-1.90) in the moderate group, and 0.21 (IQR 0.12-1.2) in the mild group. Increasing procalcitonin was associated with increasing severity (range of aORs: 1.03-1.25) and increased LOS (range of aORs: 1.04-1.36). All comparisons were statistically significant.

CONCLUSIONS

Higher procalcitonin was associated with increased severity and LOS. Procalcitonin may be useful in helping clinicians evaluate pneumonia severity.