Validity and reliability of clinical signs in the diagnosis of dehydration in children.

OBJECTIVE: To determine the validity and reliability of various clinical findings in the diagnosis of dehydration in children.
DESIGN: Prospective cohort study.
SETTING: An urban pediatric hospital emergency department. PARTICIPANTS: One hundred eighty-six children ranging in age from 1 month to 5 years old with diarrhea, vomiting, or poor oral fluid intake, either admitted or followed as outpatients. Exclusion criteria included malnutrition, recent prior therapy at another facility, symptoms for longer than 5 days' duration, and hyponatremia or hypernatremia.
METHODS: All children were evaluated for 10 clinical signs before treatment. The diagnostic standard for dehydration was fluid deficit as determined from serial weight gain after treatment. MAIN
RESULTS: Sixty-three children (34%) had dehydration, defined as a deficit of 5% or more of body weight. At this deficit, clinical signs were already apparent (median = 5). Individual findings had generally low sensitivity and high specificity, although parent report of decreased urine output was sensitive but not specific. The presence of any three or more signs had a sensitivity of 87% and specificity of 82% for detecting a deficit of 5% or more. A subset of four factors-capillary refill >2 seconds, absent tears, dry mucous membranes, and ill general appearance-predicted dehydration as well as the entire set, with the presence of any two or more of these signs indicating a deficit of at least 5%. Interobserver reliability was good to excellent for all but one of the findings studied (quality of respirations).
CONCLUSIONS: Conventionally used clinical signs of dehydration are valid and reliable; however, individual findings lack sensitivity. Diagnosis of clinically important dehydration should be based on the presence of at least three clinical findings.