Performance Comparison of Infection Prediction Scores in a South African Neonatal Unit: A Retrospective Case-Control Study

Abstract

Background and objectives: Infection prediction scores are useful ancillary tests in determining the likelihood of neonatal hospital-acquired infection (HAI), particularly in very low birth weight (VLBW; <1,500 g) infants who are most vulnerable to HAI and have high antibiotic utilization rates. None of the existing infection prediction scores were developed for or evaluated in South African VLBW neonates.

Methods: We identified existing infection prediction scores through literature searches and assessed each score for suitability and feasibility of use in resource-limited settings. Performance of suitable scores were compared using a retrospective dataset of VLBW infants (2016-2017) from a tertiary hospital neonatal unit in Cape Town, South Africa. Sensitivity, specificity, predictive values, and likelihood ratios were calculated for each score.

Results: Eleven infection prediction scores were identified, but only five were suitable for use in resource-limited settings (NOSEP1, Singh, Rosenberg, and Bekhof scores). The five selected scores were evaluated using data from 841 episodes of HAI in 659 VLBW infants. The sensitivity for the scores ranged between 3% (NOSEP1 ≥14; proven and presumed infection), to a maximum of 74% (Singh score ≥1; proven infection). The specificity of these scores ranged from 31% (Singh score ≥1; proven and presumed infection) to 100% (NOSEP1 ≥11 and ≥14, NOSEP-NEW-1 ≥11; proven and presumed infection).

Conclusion: Existing infection prediction scores did not achieve comparable predictive performance in South African VLBW infants and should therefore only be used as an adjunct to clinical judgment in antimicrobial decision making. Future studies should develop infection prediction scores that have high diagnostic accuracy and are feasible to implement in resource-limited neonatal units.

Keywords: bloodstream infection; infection prediction scores; low birth weight; neonate; sepsis.

FIGURE 1

Flow diagram of neonatal hospital-acquired infection episodes in very low birth weight infants included in the analysis. ¹Monitoring purposes: this refers to blood culture/s performed after 72 h of life in response to a positive blood culture or raised CRP obtained <72 h of life to monitor response to antimicrobial therapy.

FIGURE 2

(A) Graph showing the receiver operating characteristic (ROC) curves for the analysis of the diagnostic accuracy of the NOSEP1 score (area under curve 0.753), NOSEP-NEW-1 score (area under curve 0.737), Singh score (area under curve 0.555), Rosenberg score (area under curve 0.594), and Bekhof score (area under curve 0.641), for the prediction of proven hospital-acquired infection. (B) Graph showing the ROC curves for the analysis of the diagnostic accuracy of the NOSEP1 score (area under curve 0.898), NOSEP-NEW-1 score (area under curve 0.820), Singh score (area under curve 0.550), Rosenberg score (area under curve 0.566), and Bekhof score (area under curve 0.620), for the prediction of proven hospital-acquired infection and/or presumed hospital-acquired infection. The reference line on both graphs represents a curve with no predictive value (area under curve = 0.50).