Value of white cell count in predicting serious bacterial infection in febrile children under 5 years of age De S, et al. Arch Dis Child 2014;99:493–499. doi: /archdischild David King

Clinical scenario 11 month old boy Temperature 39 C No clear focus

the results… WCC 24.5 (Neut 18) CRP 54 Urine: 1 + WCC +/- epithelial cells no organisms

The dilemma

Clinical assessment… Clinical assessment had a sensitivity of % for detecting SBI (Craig et al, 2010)

Dr Damien Roland (Leicester consultant)

Is a WCC clinically useful in excluding (or ruling in) a serious bacterial infection?

Current guidelines (NICE)… Perform FBC, CRP, blood culture, CRP, urine test, CXR (if resp signs) if < 3 months with fever Perform LP in febrile infants 15 Start empirical antibiotics if febrile infants 15. Perform investigations including FBC in older children with red or amber features (unless deemed unnecessary) CXR if WCC > 20 and temp > 39

Results

Performance of WCC in detecting SBI

Performance of ANC in detecting SBI

In summary The FBC in excluding serious bacterial infection in children is rubbish…

CASP checklist

Clearly focused issue? Well set out and considered research question.

Recruitment of patients? Only patients having FBC included in analysis (for ethical reasons)

Outcome accurately measured to minimise bias? Relatively large number of children had CXRs ? Overdiagnosed pneumonias

Follow-up of patients? >95% follow-up rate

Are the results precise and do you believe them? Results seem valid Study has some weaknesses but overall findings are convincing

Can the results be applied locally?

WCC thresholds likely to be reviewed when NICE guidelines updated Still waiting for the “perfect test”… The future?