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Accuracy of the “traffic light” clinical decision rule for serious bacterial infections in young children with fever: a retrospective cohort study

BMJ 2013; 346 doi: (Published 13 February 2013) Cite this as: BMJ 2013;346:f866
  1. Sukanya De, PhD student1,
  2. Gabrielle J Williams, clinical researcher1,
  3. Andrew Hayen, associate professor of biostatistics12,
  4. Petra Macaskill, professor of biostatistics1,
  5. Mary McCaskill, medical director3,
  6. David Isaacs, senior staff specialist4,
  7. Jonathan C Craig, senior staff specialist15
  1. 1Screening and Test Evaluation Program, School of Public Health, University of Sydney, Sydney 2006, Australia
  2. 2School of Public Health and Community Medicine, University of New South Wales, Sydney 2052
  3. 3Department of Emergency Medicine, The Children’s Hospital at Westmead, Sydney 2145
  4. 4Department of Infectious Diseases and Microbiology, The Children’s Hospital at Westmead
  5. 5Department of Nephrology, The Children’s Hospital at Westmead
  1. Correspondence to: S De{at}
  • Accepted 5 February 2013


Objectives To determine the accuracy of a clinical decision rule (the traffic light system developed by the National Institute for Health and Clinical Excellence (NICE)) for detecting three common serious bacterial infections (urinary tract infection, pneumonia, and bacteraemia) in young febrile children.

Design Retrospective analysis of data from a two year prospective cohort study

Setting A paediatric emergency department.

Participants 15 781 cases of children under 5 years of age presenting with a febrile illness.

Main outcome measures Clinical features were used to categorise each febrile episodes as low, intermediate, or high probability of serious bacterial infection (green, amber, and red zones of the traffic light system); these results were checked (using standard radiological and microbiological tests) for each of the infections of interest and for any serious bacterial infection.

Results After combination of the intermediate and high risk categories, the NICE traffic light system had a test sensitivity of 85.8% (95% confidence interval 83.6% to 87.7%) and specificity of 28.5% (27.8% to 29.3%) for the detection of any serious bacterial infection. Of the 1140 cases of serious bacterial infection, 157 (13.8%) were test negative (in the green zone), and, of these, 108 (68.8%) were urinary tract infections. Adding urine analysis (leucocyte esterase or nitrite positive), reported in 3653 (23.1%) episodes, to the traffic light system improved the test performance: sensitivity 92.1% (89.3% to 94.1%), specificity 22.3% (20.9% to 23.8%), and relative positive likelihood ratio 1.10 (1.06 to 1.14).

Conclusion The NICE traffic light system failed to identify a substantial proportion of serious bacterial infections, particularly urinary tract infections. The addition of urine analysis significantly improved test sensitivity, making the traffic light system a more useful triage tool for the detection of serious bacterial infections in young febrile children.


  • Contributors SD assisted with the study design, compiled the results, and wrote the manuscript. GJW assisted with the study design, obtained ethical permission, took part in data collection, in database design, monitoring, and reporting, and in medical staff training, and reviewed the manuscript. AH undertook statistical analysis, presented the results, and reviewed the manuscript. PM contributed to the statistical analysis design, interpretation of analysis, and manuscript review. DI formulated the disease definitions, was member of the final diagnoses committee, and reviewed the manuscript. MMC facilitated the study in the emergency department, formulated disease definitions, reviewed the febrile template, undertook training and support of the emergency staff, and reviewed the manuscript. JCC undertook the design of the study, presentation of results, and manuscript review. All authors had full access to all data and analysis, JCC, SD, GW, and PM act as the guarantors.

  • Funding This is a sub-study of FEVER, which was funded by the National Health and Medical Research Council of Australia (grant Nos 211205 and 402764). The funding source had no influence on study design; collection, analysis, or interpretation of data; writing the report; or the decision to submit the paper for publication.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.”.

  • Ethical approval: Approval was obtained through the University of Sydney Human Research Ethics Committee (ID 2405) and the Royal Alexandra Hospital for Children Ethics Committee (ID 99023, 2004/113).

  • Data sharing: No additional data available.

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