Diagnostic accuracy of clinical signs used to identify electrolyte disturbances in children with diarrhoea

Abstract

Background: No studies have assessed the diagnostic accuracy of clinical signs of electrolyte disturbances in children with dehydrating diarrhoea.

Aims: To assess the diagnostic accuracy and reliability of clinical signs previously reported to be associated with plasma sodium and potassium disturbances in children.

Methods: A cross-sectional analytical study of 476 children aged 6 weeks to 2 years, admitted to a rehydration unit in Cape Town, South Africa. The clinical signs were elicited on admission by one of 58 junior doctors. Operational definitions of clinical signs were provided, but no additional training was given. Admission plasma electrolyte levels were the reference standard. Likelihood ratios were the primary measures of diagnostic accuracy, with reliability expressed as weighted Kappa scores.

Results: Inter-observer agreement was generally poor, and confidence intervals were wide. None of the 18 signs studied had clinically meaningful diagnostic accuracy even for severe plasma sodium and potassium abnormalities.

Conclusions: None of the clinical signs assessed were useful in clinical practice. Additional training would improve the accuracy of the signs.

Keywords:

• Diarrhoea
• electrolyte disturbances
• hypokalaemia
• hyponatraemia
• hypernatraemia
• diagnosis
• observer variation
• sensitivity
• specificity

The study was funcded by the Medical Research Council, South Africa, the University of Cape Town and the Deutsche Geselleschaft für Technische Zusammenarbeit (GTZ) GmbH.

Further details of the study are available from the authors on request.