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Objective To collate all available evidence on the diagnostic value of laboratory tests for the diagnosis of serious infections in febrile children in ambulatory settings. Design Systematic review. Data sources Electronic databases, reference tracking, and consultation with experts. Study selection Studies were selected on six criteria: design (studies of diagnostic accuracy or deriving prediction rules), participants (otherwise healthy children and adolescents aged 1 month to 18 years), setting (first contact ambulatory care), outcome (serious infection), features assessed (in first contact care), and data reported (sufficient to construct a 2×2 table). Data extraction Quality assessment was based on the quality assessment tool of diagnostic accuracy studies (QUADAS) criteria. Meta-analyses were done using the bivariate random effects method and hierarchical summary receiver operating characteristic curves for studies with multiple thresholds. Data synthesis None of the 14 studies identified were of high methodological quality and all were carried out in an emergency department or paediatric assessment unit. The prevalence of serious infections ranged from 4.5% to 29.3%. Tests were carried out for C reactive protein (five studies), procalcitonin (three), erythrocyte sedimentation rate (one), interleukins (two), white blood cell count (seven), absolute neutrophil count (two), band count (three), and left shift (one). The tests providing most diagnostic value were C reactive protein and procalcitonin. Bivariate random effects meta-analysis (five studies, 1379 children) for C reactive protein yielded a pooled positive likelihood ratio of 3.15 (95% confidence interval 2.67 to 3.71) and a pooled negative likelihood ratio of 0.33 (0.22 to 0.49). To rule in serious infection, cut-off levels of 2 ng/mL for procalcitonin (two studies, positive likelihood ratio 13.7, 7.4 to 25.3 and 3.6, 1.4 to 8.9) and 80 mg/L for C reactive protein (one study, positive likelihood ratio 8.4, 5.1 to 14.1) are recommended; lower cut-off values of 0.5 ng/mL for procalcitonin or 20 mg/L for C reactive protein are necessary to rule out serious infection. White blood cell indicators are less valuable than inflammatory markers for ruling in serious infection (positive likelihood ratio 0.87-2.43), and have no value for ruling out serious infection (negative likelihood ratio 0.61-1.14). The best performing clinical decision rule (recently validated in an independent dataset) combines testing for C reactive protein, procalcitonin, and urinalysis and has a positive likelihood ratio of 4.92 (3.26 to 7.43) and a negative likelihood ratio of 0.07 (0.02 to 0.27). Conclusion Measuring inflammatory markers in an emergency department setting can be diagnostically useful, but clinicians should apply different cut-off values depending on whether they are trying to rule in or rule out serious infection. Measuring white blood cell count is less useful for ruling in serious infection and not useful for ruling out serious infection. More rigorous studi...

A gut feeling about the seriousness of illness in children is an instinctive response by clinicians to the concerns of the parents and the appearance of the children. It should trigger action such as seeking a second opinion or further investigations. The observed association between intuition and clinical markers of serious infection means that by reflecting on the genesis of their gut feeling, clinicians should be able to hone their clinical skills.

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ObjectiveDespite the growing number of point-of-care (POC) tests available, little research has assessed primary care clinician need for such tests. We therefore aimed to determine which POC tests they actually use or would like to use (if not currently available in their practice).DesignCross-sectional survey.SettingPrimary care in Australia, Belgium (Flanders region only), the Netherlands, the UK and the USA.ParticipantsPrimary care doctors (general practitioners, family physicians).Main measuresWe asked respondents to (1) identify conditions for which a POC test could help inform diagnosis, (2) from a list of tests provided: evaluate which POC tests they currently use (and how frequently) and (3) determine which tests (from that same list) they would like to use in the future (and how frequently).Results2770 primary care clinicians across five countries responded. Respondents in all countries wanted POC tests to help them diagnose acute conditions (infections, acute cardiac disease, pulmonary embolism/deep vein thrombosis), and some chronic conditions (diabetes, anaemia). Based on the list of POC tests provided, the most common tests currently used were: urine pregnancy, urine leucocytes or nitrite and blood glucose. The most commonly reported tests respondents expressed a wish to use in the future were: D-dimer, troponin and chlamydia. The UK and the USA reported a higher actual and desired use for POC tests than Australia, Belgium and the Netherlands. Our limited data suggest (but do not confirm) representativeness.ConclusionsPrimary care clinicians in all five countries expressed a desire for POC tests to help them diagnose a range of acute and chronic conditions. Rates of current reported use and desired future use were generally high for a small selection of POC tests, but varied across countries. Future research is warranted to explore how specific POC tests might improve primary care.