Retrospective Study Of Epidemiology And Disease Burden Of Hospitalized Children With Influenza In Suzhou City

Section 1 Epidemiology and clinical characteristics of hospitalized children with laboratory-confirmed influenzaObjective To describe the epidemiological distribution and clinical characteristics of hospitalized children with laboratory-confirmed influenza in Suzhou Children's hospital during 2005-2009, so as to offer information for the immunization and prevention of influenza children. Method Retrospective study. According to the results of laboratory tests and historical records, we collected the useful information and analyzed the data with SPSS18.0 and SAS9.1. Results There were 480 children with laboratory-confirmed influenza in total in Suzhou Children's hospital during 2005-2009, with the positive rate 2.7%. The period between November- April next year was the peak of seasonal influenza. There was also a summer period between July- September. The average temperature and mean relative humidity was relatively lower in the peak period but higher in the summer period. Three hundred and four children with laboratory confirmed influenza were from urban districts of Suzhou City. Two hundred and eighty six children (59.6%) were male and 194(40.4%)were female. Children (?)6 months old and those (?)5 years old accounted for 28.5% and 87.3% of all the influenza children respectively. There were 414 children(86.3%) with influenza A and 66 children(13.7%) with influenza B. The median of the length of hospitalization was 7 days, significantly longer for the children (?)6 months old than those >5 years old. There were 101 children(21.0%) with various high-risk diseases,39 children(8.1%) with supplemental oxygen treatment and 13 children(2.7%) were referred to ICU. The median of oxygen saturation was 98.2%, increasing with the growing age. The most common clinical characteristic was fever(82.9%) and the most common complication was nasosinusitis(8.8%). Dyspnea, septicemia and AOM was rare. There were 115/387 children (29.7%) confirmed to be co-infected with bacteria. Sixty children(52.2%) were co-infected with streptococcus pneumonia, and its percentage increased with the growing age. The peak period of respiratory syscytial virus(RSV) was November-April next year. Conclusion Influenza in Suzhou was seasonal distributed. The peak period of RSV was overlapped with influenza. Children with influenza A and those <5 years old accounted for the most. the children with high-risk diseases were very common and were key population for immunization. Streptococcus pneumonia was the most common co-infected bacterium, leading to pneumonia and hospitalization.Section 2 Analysis of hospitalization cost and its influencing factorsObjective To describe the distribution of the hospitalization cost, and to analyze the influencing factors, so as to provide evidence for influenza prevention. Method Retrospective study. According to historical information system(HIS) of Suzhou Children's Hospital, we collected the various hospitalization costs of the study objects. We analyzed the influencing factors with univariate analysis, logistic analysis and regression tree. Software SPSS18.0 and SAS9.1 were used. Results During 2005-2009, the lowest hospitalization of influenza children was 736 yuan, the highest was 15679 yuan, and the median was 3934 yuan. There was no significant difference among(?)6m,7m-,25m- and >60m age groups. It was significantly higher in male than in the female. The influenza children in ICU had higher hospitalization cost and longer length of hospitalization than those in wards. Among the total hospitalization cost, the cost for treatment accounted for the most(44%), and the cost for doctor diagnosis accounted for the least(12%). The cost of laboratory test, western medicine and others(air-conditioner, water, electricity, etc.) was highest among the cost of tests, treatments and nursing, respectively. The distribution of hospitalization cost among the children with influenza, the children with RSV or virus-negative children was similar, with the highest hospitalization cost and the longest length of hospitalization in influenza children. Univariate analysis found that the hospitalization cost was higher in the influenza children having supplemental oxygen than those never having supplemental oxygen(OR=10.07), it was also higher in those with high-risk diseases than those without high-risk diseases(OR=1.70), and the longer the length of hospitalization was, the higher the hospitalization cost would be(OR=2.20). Logistic regression found that besides the factors whether or not had supplemental oxygen(OR=12.00) and the length of hospitalization(OR=2.37), age was also an significant influencing factor. When other factors were kept still, comparing with the influenza children (?)6 months old, those 25-60 months old(OR=3.54) and those >60months old(OR=4.09) had higher hospitalization cost. Regression tree found that the influencing factors, arranged in order of importance, were the length of hospitalization, whether or not had supplemental oxygen, the age, the level of CRP. The children hospitalized (?)6.5 days cost least while those hospitalized>14.0 days cost most. Conclusion The economic burden of influenza children in Suzhou was relatively heavy, and could be influenced by the factors, such as the length of hospitalization, whether or not had supplemental oxygen, the age, the level of CRP, whether or not had high-risk diseases.Section 3 Estimation of the disease burden of hospitalized children with influenza in SuzhouObjective To estimate the direct economic burden per capita and the excess rate of hospitalization associated with influenza among the children less than 5 years old in Suzhou City, so as to provide information for the immunization and cost-effectiveness analysis of vaccine. Method Using the positive rate of influenza, the average hospitalization cost of Suzhou Children's hospital and the per capita wage in Suzhou City during 2005-2009, we estimated the direct economic burden per capita associated with influenza among the children less than 5 years old in Suzhou City. Combined with the data of annual birth population among resident population during 2005-2009, we also estimated the excess rate of hospitalization associated with influenza among the children less than 5 years old in Suzhou City. Results During 2005-2009, there were 1,153,740 children less than 5 years old in all, among which 233,507 (20.2%) were estimated with respiratory tract infection and 8485 were estimated with influenza among the children less than 5 years old. The direct economic burden per capita associated with influenza was estimated to be 60.9 yuan, including 29.8 yuan for direct medical cost per capita and 31.1 yuan for direct non-medical cost. The direct economic burden of children (?)6 months old was highest(76.6 yuan) and it decreased with the growing age. The excess rate of hospitalization associated with influenza among children less than 5 years old in different years and age groups was estimated to between 15.4-378.3/10,0000. Comparing the peak period with the summer period and the base-line period, the excess rate of hospitalization associated with influenza among children less than 5 years old was estimated to be 106.1/100,000 and 148.0/100,000, respectively, highest in the children 7-24 months old and lowest in those 25-60 months old. Conclusion The direct economic burden per capita and the excess rate of hospitalization associated with influenza among the children less than 5 years old in Suzhou City were both high, and could be underestimated, indicating that the immunization of influenza vaccine could be beneficial in preventing seasonal influenza in Suzhou City.