[Severe cases with hand, foot and mouth disease: data based on national pilot hand, foot and mouth disease surveillance system].

To investigate the clinical severity, etiological classification and risk factors of severe cases with hand, foot and mouth disease (HFMD). A total of 1 489 records on severe and fatal HFMD cases reported to the national pilot surveillance system of HFMD were used to analyze the demographic, medical treatment, etiological classification of the cases. Treatment outcome related risk factors were also studied with multi-variable stepwise logistic regression method. Seven out of the 1 489 severe HFMD cases died of this disease. A total of 960 (72.9) were under three years old and 62.9 were male and most of the cases (937, 62.9) resided in rural areas. Among all the cases, 494 (33.2) went to seek the first medical assistance at the institutions of village or township level. Durations between disease onset and first medical attendance, being diagnosed as the disease or diagnosed as severe cases were 0(0-1) d, 1 (0-2) d and 2 (1-4) d, respectively. In total, 773 (51.9) of the severe HFMD cases were diagnosed as with aseptic meningitis, 260 (17.5) with brainstem encephalitis, 377 (25.3) with non-brainstem encephalitis, 6 (0.4) with encephalomyelitis, 1 (0.1) with acute flaccid paralysis, 4 (0.3) with pulmonary hemorrhage/pulmonary edema and 68 (4.6) with cardiopulmonary failure. Of the etiologically diagnosed 1 217 severe and fatal HFMD cases, 642 (52.8) were with EV71, other enterovirus 261 (21.5), Cox A16 36 (3.0), 1 (0.1) with both EV71 and Cox A16. However, 277 (22.8) showed negative on any pathogenic virus. Complication (=3.15, =0.002) and duration between onset and diagnosed as severe cases (=3.95, <0.001) were shown as key factors related to treatment outcomes. Most severe HFMD cases appeared in boys, especially living in the rural areas. Frequently seen complications would include aseptic meningitis, non-brainstem encephalitis and brainstem encephalitis. EV71 was the dominant etiology for severe and fatal cases. Early diagnosis and complication control were crucial, related to the treatment outcome of HFMD.