Estimating the probability of neonatal early-onset infection on the basis of maternal risk factors.
OBJECTIVE
To develop a quantitative model to estimate the probability of neonatal early-onset bacterial infection on the basis of maternal intrapartum risk factors.


METHODS
This was a nested case-control study of infants born at ≥34 weeks' gestation at 14 California and Massachusetts hospitals from 1993 to 2007. Case-subjects had culture-confirmed bacterial infection at <72 hours; controls were randomly selected, frequency-matched 3:1 according to year and birth hospital. We performed multivariate analyses and split validation to define a predictive model based only on information available in the immediate perinatal period.


RESULTS
We identified 350 case-subjects from a cohort of 608,014 live births. Highest intrapartum maternal temperature revealed a linear relationship with risk of infection below 100.5°F, above which the risk rose rapidly. Duration of rupture of membranes revealed a steadily increasing relationship with infection risk. Increased risk was associated with both late-preterm and postterm delivery. Risk associated with maternal group B Streptococcus colonization is diminished in the era of group B Streptococcus prophylaxis. Any form of intrapartum antibiotic given >4 hours before delivery was associated with decreased risk. Our model showed good discrimination and calibration (c statistic = 0.800 and Hosmer-Lemeshow P = .142 in the entire data set).


CONCLUSIONS
A predictive model based on information available in the immediate perinatal period performs better than algorithms based on risk-factor threshold values. This model establishes a prior probability for newborn sepsis, which could be combined with neonatal physical examination and laboratory values to establish a posterior probability to guide treatment decisions.
Department of Newborn Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA. kpuopolo@partners.org
Karen M
KM
Puopolo
David
D
Draper
Soora
S
Wi
Thomas B
TB
Newman
John
J
Zupancic
Ellice
E
Lieberman
Myesha
M
Smith
Gabriel J
GJ
Escobar
D000328:Adult; D017668:Age of Onset; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D016470:Bacteremia / Q000175:diagnosis / Q000453:epidemiology* / Q000635:transmission*; D001499:Bayes Theorem; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006090:Gram-Negative Bacteria / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000302:isolation & purification; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000188:drug therapy / Q000453:epidemiology / Q000209:etiology; D018445:Infectious Disease Transmission, Vertical / Q000706:statistics & numerical data*; D008297:Male; D015999:Multivariate Analysis; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D015995:Prevalence; D011336:Probability; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology
D000900:Anti-Bacterial Agents