Diagnosing serious infections in acutely ill children in ambulatory care: diagnostic accuracy of a clinical decision tree together with a point-of-care C-reactive protein test.

The problem

Acute illness is the most common presentation of children to ambulatory care. In contrast, serious infections are rare and often present at an early stage. To avoid complications or death, early recognition and adequate referral are essential. In a recent large study children were included prospectively to construct a symptom-based decision tree with a sensitivity and negative predictive value of nearly 100%. Aiming to improve detection of serious infections in ambulatory care, and reduce the number of false positives, point-of-care tests might be useful, providing an immediate result at bedside. The most probable candidate is C-reactive protein.

The approach

This is a diagnostic accuracy study of signs, symptoms and point-of-care tests for serious infections in ambulatory care. Acutely ill children presenting to a general practitioner or paediatrician were included consecutively in Flanders, Belgium. Children testing positive on the decision tree got a point-of-care C-reactive protein test. The outcome of interest was hospital admission more than 24 hours with a serious infection within 5 days.

Findings

8962 children were consecutively included from 15 February 2013 to 28 february 2014 by 170 general practitioners and 106 paediatricians, identifying 283 serious infections. In the GP setting, the symptom-based 4-step decision tree reached a sensitivity of 100% (95% CI 71.5-100%) ruling out serious infections. Adding the results of the point-of-care C-reactive protein test after a positive result on the decision tree increased the specificity from 83.6% (95% CI 82.3-84.9%) to 89.5% (95%CI 88.3 - 90.5%) while maintaining a 100% sensitivity in the GP setting. A multivariable model, based on objective easy-to-assess clinical features was developed in the specialist setting, reaching a sensitivity of 97.1% (95% CI 94.3-98.7%) and a negative predictive value of 99.6% (95% CI 99.2-99.8%).

Consequences

Adding point-of-care C-reactive protein test results to a validated signs and symptoms-based decision tree aids identifying serious infections in the GP setting without increasing the number of investigations and admissions in acutely ill children. This practical tool for diagnostic triage of acutely ill children has shown to be valid in general practice and is ready to be implemented in routine care. We propose a new multivariable model to be used as a triage instrument in specialist settings to safely rule out serious infections.

Credits

• Jan Verbakel, Department of Public Health and Primary Care, Leuven, Belgium