Estimating Influenza Burden Using Etiology Surveillance Of Sentinel Hospital And Community Investigation

Objective:Evaluate the incidence, direct medical costs and indirect cost of Influenza Like Illness(ILI) case through community investigation, analysis their medical seeking behaviors, explore a method to estimate influenza incidence by combing the etiology surveillance results of sentinel hospital with community investigation results.Methods:we collected the address information of patients seeking care at influenza surveillance sentinel hospital(ChangSha central hospital), calculated their distance from the hospital, acquired the P75 distance. Taking this distance as the radius and the hospital as the center of the circle, we obtained a circle which would sever as the hospital medical service scope. According to the stratified cluster sampling and the cross-sectional survey sample size calculation method, we held a household survey within the scope. We adopted a self-made questionnaire which was modified by experts repeatedly. After preliminary investigation, we modified the draft further more and got the questionnaire finally. Using SPSS 20.0 to analyzethe survey data, we obtained the I LI incidence, direct medical costs and the indirect costs of ILI case and analysis the impact factors of medical seeking behavior and medical institutions choosing respectively by Logistic regression analysis. Finally we estimated the influenza incidence of community residents using the influenza positive rate of hospital etiology monitoring and calculated influenza incidence of community residents eventually. The research would be performed in January to March andApril to June of 2015, respectively.Results:We investigated 24151 people during these two periods, among them 724 ILI case were found. The ILI incidence was 2997.8/100000(95% CI:2782.7/100000-3212.9/100000), the incidence of men was higher than women, children aged 0-5 had the highest incidence, the average age of ILI case was 6 years old (IQR:3-31).Children under the age of 15 usually attack more episodes ILI.62.8% of ILI case chose self-medication treatment firstly,62.8% of ILI case sought care in medical institutions, among them 56.5% of patients received outpatient treatment,6.7% of patients accepted inpatient treatment. Cost per episode for ILI patients was ￥565.2 (±1106.7), self medication cost per episode was ￥106.7 (±192.1), cost per episode for ILI outpatients was ￥523.0 (±696.3), cost per episode for ILI inpatients was ￥3634.2 (±2859.8).38.4% of the patients with ILI were absence from day care, the mean lost day was 5.9 (±7.7). 26.9% of patient parent were absence from work, the mean lost day was5.6 (±6.6). Multivariable Logistic regression analysis result showed that different age groups were the impact factor of medical seeking behavior. Logistic regression analysis found that small age group, men and higher income group were more likely to seek care in municipal-level hospital or above. As the result of etiology surveillance of hospital shown, influenza positive rate during January to March and April to June in 2015 were 14.3% and 5.0% respectively. With these results, we estimated the influenza burden of community residents within the hospital medical service scope. The influenza incidence of community residents during January to March and April to June were 305.1/100000(95% CI:201.4/100000-399.2/100000) and 191.0/100000(95%CI:113.3/ 100000-266.7/100000) respectively.Conclusion:This study estimated influenza disease burden by combing the etiology results of sentinel hospital with community survey.The influenza incidence of community residents during January to March and April to June were 305.1/100000(95% CI: 201.4/100000-399.2/100000) and 191.0/100000 (113.3/100000-266.7/100000). Our study provided the guidance for public health decision. The community survey results showed that ILI brought heavy medical burden for community residents. Children under 15 years old were the highest risk group. Cost per episode for ILI aged over 60 years old was the highest. Most of the ILI cases sought care in municipal-level hospital or above. This indicated that the health policy maker should allocated health resources more rationally and improved the basic medical services utilization rate.