A case–control study of risk factors for severe hand–foot–mouth disease among children in Ningbo, China, 2010–2011

BackgroundA small fraction of hand–foot–mouth disease (HFMD) progression from the onset of severity to fatality may be remarkably rapid. Early recognition of children at risk of severity is critical to increase treatment effectiveness and reduce acute mortality.MethodsA frequency-matched case–control study was conducted between January 2010 and June 2011 in Ningbo to identify risk factors associated with the occurrence of severity in children with HFMD. Data including demographic characteristics, clinical features, and laboratory test results were collected by trained interviewers through retrospective medical record review and/or face-to-face interviews with children’s parents using a standardized questionnaire.ResultsEighty-nine cases with severe HFMD and 267 controls with mild HFMD were recruited in this study. Palm rashes (OR = 0.004, 95%CI = 0.000–0.039, p < 0.001), oral ulcers or herpes (OR = 0.001, 95%CI = 0.000–0.009, p < 0.001) were significantly associated with protection against severity, and an increased risk of severity was significantly associated with the presence of, e.g., a high fever of over 39°C for more than 3 days (OR = 2.217, 95%CI = 1.082–4.541, p = 0.030), leg trembling (OR = 29.008, 95%CI = 1.535–548.178, p = 0.025), papule rash (OR = 4.622, 95%CI = 1.110–19.252, p = 0.035), a raised WBC count > 10.8 × 109/L (OR = 4.495, 95%CI = 1.311–15.415, p = 0.017), and human enterovirus 71 infection (OR = 39.172, 95%CI = 9.803–156.522, p < 0.001).ConclusionClinicians should pay increased attention to children diagnosed as HFMD with the independent risk factors above.