Updated Posterior Probability and NNTa

Clinical PresentationbPrevious Probability (Sepsis Risk at Birth, Based on Maternal Risk Factorsb) Rate per 1000 Live Births
Well appearing
 PP0.11 (0.08–0.13)1.08 (0.70–1.65)6.74 (3.09–16.06)
 NNT9370 (7418–12 073)923 (605–1428)148 (62–323)
Equivocal presentation
 PP1.31 (0.93–1.84)11.07 (5.02–27.74)
 NNT763 (543–1076)90 (36–199)
Clinical illness
 PP4.66 (2.80–8.04)62.94 (12.94–583.72)
 NNT214 (124–357)16 (2–77)
  • a In this table, the columns show 3 sepsis risk at birth ranges calculated based on maternal risk factors (see citation 2), which constitute the initial previous probability for a given neonate. These are then combined with the infant’s clinical presentation (rows) to generate an updated PP and the NNT. The updated PPs, with their associated 95% CIs in parentheses, are expressed as the rate of sepsis per 1000 live births. The NNT (total number of newborns one would need to treat to ensure that all cases of sepsis were treated within a given risk group) is estimated by dividing 1000 by the rate per thousand live births. For the entire study population, in which the incidence was 0.58/1000 (350 cases in a population of 608 014), the number NNT is 1737 (95% CI 1562–1.923). See text for details on how we estimated 95% CIs. Some cells were combined because of very small numbers. For example, only 2.9% of all infants (but 42% of all sepsis cases) showed clinical illness; within this group, infants with a sepsis risk at birth of ≥1.54/1000, who constituted 0.2% of all live births (but 8.3% of all sepsis cases), had a PP of 25.4/1000. Detailed breakdowns for all clinical presentations are provided in the Supplemental Information.

  • b See text and Supplemental Information for a description of how sepsis risk at birth ranges were established. The hierarchical, mutually exclusive clinical categorizations are described in Table 1; a description of their development is in the Supplementarl Information.