Case definition selection and evaluation research of the hospital-based febrile respiratory syndromic surveillance

Objective To explore the early clinical symptom characteristics of patients confirmed common acute respiratory infectious and to select combinations of common clinical symptoms in order to provide references for intelligent febrile respiratory syndromic surveillance in the hospital-based to aid in early warning of acute respiratory infectious disease outbreaks.

Methods Data on clinical manifestations and laboratory testing results was collected from nationwide surveillance of all-age patients with acute respiratory infections between 2011−2015. Descriptive analysis was used to describe the early clinical characteristics in different population groups. Sensitivity, specificity, positive and negative predictive values were calculated for various symptom complexes.

Results Fever and cough were the most common symptoms of the cases, although proportions of early common respiratory symptoms including degree of fever, cough, sore throat, runny nose and others varied by age-group and pathogen type. Fever (≥37.2 ℃) plus cough or sore throat or runny nose case definition had maximum sensitivity (71.63%) but low specificity (33.52%). No difference was found in the improvement of sensitivity by adding sputum to the criteria (P>0.05). Compared with other symptom combinations, the difference of positive predictive value and negative predictive value was slight, which was 33.41% and 71.73%, respectively.

Conclusions Case definition of fever (≥37.2 ℃) plus cough or sore throat or runny nose was more sensitive in the hospital-based febrile respiratory syndromic surveillance which would be useful for early detecting clusters and abnormal rises of acute respiratory infectious diseases cases.