Objective  To explore the risk factors and occurrence of severe hand, foot and mouth disease (HFMD) in children.

  Methods  A total of 271 children with HFMD were selected and divided into two groups according to severity of disease. The influence of clinical features and laboratory data on severe HFMD was analyzed.

  Results  There were no significant differences in gender, type of children, type of household registration, residence, preterm delivery, birth weight, delivery status, maximum body temperature, convulsion, pale face, runny nose, diarrhea, hand and foot rash, oral herpes, hip rash between the two groups (P>0.05). There were significant differences in age, breast-feeding condition, time from onset to treatment, vulnerability, fatigue, limb tremor, lethargy, dyspnoea, dyspnea, vomiting, leukocyte count, blood glucose, C reactive protein, creatine kinase isoenzyme (CK-MB) and virus infection type between the two groups (P < 0.05). In term of cytokine level, the levels of interleukin-4 (IL-4), interleukin-6 (IL-6), interleukin-6 (IL-8), interleukin-10 (IL-10) and interferon-γ (IFN-γ) in severe HFMD group were significantly higher than those in normal HFMD group (P < 0.05). In ROC curve analysis, IL-6, IL-10 and IFN-γ played important roles in the differentiation of common HFMD and severe HFMD. Logistic regression analysis showed that IL-6 ≥46.0 pg/mL, IL-10 ≥22.7 pg/mL and IFN-γ ≥81.9 pg/mL were important predictors of severe HFMD.

  Conclusion  Clinicians and parents should pay attention to HFMD children with age less than 3 years old, trembling limbs, lethargy, irritability, elevated blood sugar and CK-MB and EV-71 virus infection. IL-6 ≥46.0 pg/mL, IL-10 ≥22.7 pg/mL and IFN-γ ≥81.9 pg/mL could be used as the good predictors of severe HFMD in children.