Procalcitonin as a marker of serious bacterial infections in febrile children younger than 3 years old.

Objectives There is no perfectly sensitive or specific test for identifying young, febrile infants and children with occult serious bacterial infections (SBIs). Studies of procalcitonin (PCT), a 116-amino-acid precursor of the hormone calcitonin, have demonstrated its potential as an acute-phase biomarker for SBI. The objective of this study was to compare performance of serum PCT with traditional screening tests for detecting SBIs in young febrile infants and children. Methods This was a prospective, multicenter study on a convenience sample from May 2004 to December 2005. The study was conducted in four emergency departments (EDs): one pediatric ED and three EDs with pediatric units, all with academic faculty on staff. A total of 226 febrile children 36 months old or younger who presented to the four participating EDs and were evaluated for SBI by blood, urine, and/or cerebral spinal fluid (CSF) cultures were included. Results The test characteristics (with 95% confidence intervals [CIs]) of the white blood cell (WBC) counts including neutrophil and band counts were compared with PCT for identifying SBI. Thirty children had SBIs (13.3%, 95% CI = 8.85 to 17.70). Four (13.3%) had bacteremia (including one with meningitis), 18 (60.0%) had urinary tract infections (UTIs), and eight (26.6%) had pneumonia. Children with SBIs had higher WBC counts (18.6 × 109 ± 8.6 × 109 cells/L vs. 11.5 × 109 ± 5.3 × 109 cells/L, p < 0.001), higher absolute neutrophil counts (ANCs; 10.6 × 109 ± 6.7 × 109 cells/L vs. 5.6 × 109 ± 3.8 × 109 cells/L, p = 0.009), higher absolute band counts (0.90 × 109 ± 1.1 × 109 cells/L vs. 0.35 × 109 ± 0.6 × 109 cells/L, p = 0.009), and higher PCT levels (2.9 ± 5.6 ng/mL vs. 0.4 ± 0.8 ng/mL, p = 0.021) than those without SBIs. In a multivariable logistic regression analysis, the absolute band count and PCT were the two screening tests independently associated with SBI, although the area under the receiver operating characteristic (ROC) curve for PCT was the largest (0.80, 95% CI = 0.71 to 0.89). Conclusions Procalcitonin is a more accurate biomarker than traditional screening tests for identifying young febrile infants and children with serious SBIs. Further study on a larger cohort of young febrile children is required to definitively determine the benefit of PCT over traditional laboratory screening tests for SBIs. Resumen Objetivos No existe un test con la sensibilidad o especificidad ideal es para identificar las infecciones bacterianas graves (IBG) ocultas en los ninos durante su primera infancia con fiebre. Los estudios de procalcitonina (PCT), un precursor de 116-aminoacidos de la hormona calcitonina, han demostrado su potencial como biomarcador de fase aguda para las IBG. El objetivo de este estudio es comparar el rendimiento de la PCT en plasma con las pruebas de despistaje tradicionales para la deteccion de IBG en los ninos durante la primera infancia con fiebre. Metodologia Estudio prospectivo multicentrico en una muestra de conveniencia realizado de mayo de 2004 a diciembre realizado de 2005. Este estudio se llevo a cabo en cuatro servicios de urgencias (SU): un SU pediatrico y tres SU con unidades pediatricas, todos ellos con docentes universitarios en la plantilla. Se incluyeron 226 ninos de 0 a 36 meses de edad con fiebre que acudieron a los cuatro SU participantes y se les evaluo para IBG mediante cultivos de sangre, orina y/o liquido cefalorraquideo. Resultados Los resultados (con los intervalos de confianza [IC] al 95%) del numero de leucocitos, incluyendo numero neutrofilos y blastos, y de la PCT se compararon para identificar las IBG. Treinta ninos tuvieron IBG (13,3%, IC 95% = 8,85 a 17,70). Cuatro (13,3%) tuvieron bacteremia (incluyendo uno con meningitis), 18 (60,0%) infeccion del tracto urinario y 8 (26,6%) neumonia. Los ninos con IBG tuvieron mayor numero de leucocitos (18.600 ± 8.600 cel/mm3 vs. 11.500 ± 5.300 cel/mm3, p< 0,001), numero absoluto de neutrofilos (NAN) (10.600 ± 6.700 cel/mm3 vs. 5.600 ± 3.800 cel/mm3, p = 0,009), numero absoluto de blastos (900 ± 1.100 cel/mm3 vs. 350 ± 600 cel/mm3, p = 0,009) y valores de PCT (2,9 ng/mL ± 5,6 ng/mL vs. 0,4 ng/mL ± 0,8 ng/mL, p = 0,021), que aquellos sin IBG. En un analisis multivariable de regresion logistica, el numero absoluto de blastos y la PCT fueron los dos test de despistaje que se asociaron de forma independiente con IBG, aunque el area bajo la curva de rendimiento diagnostico para la PCT fue la mayor de los test de despistaje (0,80, IC 95% = 0,71 a 0,89). Conclusiones La PCT es un biomarcador mas preciso que las pruebas de despistaje tradicionales para identificar a los ninos durante la primera infancia con IBG. Se requieren futuros estudios en una mayor cohorte de ninos durante la primera infancia con fiebre para determinar de forma definitiva el beneficio de la PCT sobre las pruebas de despistaje de laboratorio tradicionales para identificar las IBG.