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Complete blood cell counts ineffective in detecting neonatal infection
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Complete blood cell counts, whether at commonly used or highest thresholds, are inaccurate in identifying infants aged 60 days or younger with invasive bacterial infections, according to a study published in JAMA Pediatrics.
“Serum inflammatory markers, such as procalcitonin and C-reactive protein, can more accurately predict which young infants have invasive bacterial infections. However, these newer biomarkers are still being validated and are not readily available in all EDs.” Andrea T. Cruz, MD, MPH, from the sections of pediatric emergency medicine and pediatric infectious diseases at Baylor College of Medicine, and colleagues wrote. “Therefore, the ease and tradition of obtaining complete blood cell counts has led clinicians to continue to use complete blood cell parameters in algorithms to help risk stratify young febrile infants.”
To assess the ability of complete blood cell count parameters, the researchers conducted a secondary analysis of a prospective observational cohort study. This study included 26 EDs that were a part of the Pediatric Emergency Care Applied Research Network between 2008 and 2013.
Blood cultures were collected from febrile infants (those with a fever [temperature at or above 38°C]) who were previously healthy, full-term and younger than 60 days at these hospitals. Each of these infants was subjected to either cerebrospinal fluid cultures or follow-up after 7 days.
Of the 4,313 infants included in the study, 31% were between the ages of 0 and 28 days (95% CI, 30%-32%). Most infants in this cohort were white (57%) and included 2,412 boys (56%). Invasive bacterial infections were observed in 97 of these infants (2.2%; 95% CI, 1.8%-2.7%).
Sensitivities for common complete blood cell count parameter thresholds were low, with a sensitivity of 10% noted for white blood cell counts less than 5,000/µL (95% CI, 4%-16%) and 27% for white blood cell counts equal to or more than 15,000/µL (95% CI, 18%-36%). A sensitivity of 18% was observed for absolute neutrophil counts equal to or more than 10,000 (95% CI, 10%-25%), and platelet counts less than 100 x 103/µL were detected, with a sensitivity of 7% (95% CI, 2%-12%).
When optimal thresholds were considered for white blood cell count (11,600/µL), absolute neutrophil count (4,100/µL) and platelet count (362 x 103/µL), all operated under receiver operating characteristic curves (0.57 for white blood cell count, 95% CI, 0.50-0.63; 0.70 for neutrophil count, 95% CI, 0.64-0.76; and 0.61 for platelet count, 95% CI, 0.55-0.67).
“One possible explanation for the complete blood count’s poor performance is the change of pathogens causing bacterial meningitis and bacteremia in young infants,” Cruz and colleagues wrote. “In the pre-pneumococcal conjugate vaccine era, leukocytosis was commonly seen in older infants with Haemophilus and pneumococcal bacteremia. However, pathogens more commonly identified in the modern era may produce less of an inflammatory response by the host.” – by Katherine Bortz
Disclosure: Ramilo reports personal fees from Abbvie, Janssen, Regeneron and Pfizer, and grants from Janssen. All these fees and grants are not related to the current work. No other disclosures are reported.
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