[Clinical values and optimal cut-off points of basic vital signs in early identification of critical hand, foot, and mouth disease].

Objective: To study the clinical values of basic vital signs in early identification of critical hand-foot-mouth disease (HFMD).

Methods: The clinical data of 358 children with severe HFMD [212 cases in stage 2 (central nervous system involvement) and 146 cases in stage 3 (earlier stage of cardiopulmonary failure, critical type)] were reviewed. The diagnostic values of peak temperature and duration of fever, as well as the heart rate (HR), respiratory rate (RR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) in different age groups, for critical HFMD (stage 3) were analyzed using the receiver operating characteristic (ROC) curve.

Results: HFMD might progress to critical type in case of HR≥148.5 beats/minutes, RR≥36.5 times/minutes, SBP≥95 mm Hg, and DBP≥59 mm Hg among children aged 0-1 year. HR≥142.5 times/minutes, RR≥31.5 times/mintes, SBP≥103 mm Hg, and DBP≥60.5 mm Hg in children aged 1-2 years had a certain diagnostic value for critical HFMD. HFMD might progress to critical type in case of HR≥139.5 times/minutes, RR≥29.5 times/minutes, and SBP≥103 mm Hg among children≥3 years of age. The sensitivity and specificity of every indicator were higher than 0.517 and 0.769, respectively. The area under the ROC curve (AUC) for peak temperature was 0.507 (P=0.816, compared with AUC=0.5). When the duration of fever was ≥5.5 days, the sensitivity and specificity were 0.589 and 0.571, respectively.

Conclusions: HR, RR, and BP are good indicators to identify critical HFMD (stage 3) early. The optimal cut-off points conform to the age characteristics of children. DBP in children≥3 years of age, peak temperature, and duration of fever have a low value in early identification of critical HFMD.