Evaluation Of Effectiveness Of Hepatitis E Intervention Measures Based On System Dynamics Model

Background and objectiveHepatitis E is a new zoonosis caused by hepatitis E virus(HEV)infection.The clinical manifestation of HEV is similar to that of hepatitis A,which is characterized by fatigue,dysphasia and jaundice,but its severity of the symptoms and fatality rate is higher than that of the hepatitis A.HEV infection brings serious disease burden on patients,families and society.Although there have been some measures to be taken,such as hepatitis E vaccine and improved environment,pigs as the main host and source of transmission of hepatitis E made the sporadic tendency in population,which raised a challenge for prevention and control of hepatitis E.Therefore,the study aimed to understand the burden of hepatitis E disease in Jiangsu Province by means of literature search,field investigation,and expert interviews,and to construct a pig-pig,pig-human system dynamics model to evaluate the effectiveness of different interventions Methods(1)The study subjects were from hepatitis E confirmed cases reported in Nanjing city,Suzhou city,Yancheng city and Zhenjiang city in Jiangsu province from January 2015 to March 2018.The study contents included the direct and indirect economic burden,the quality adjusted life year(QALY)of hepatitis E collected by use of case investigation and hospital management system.(2)According to the transmission pathway of hepatitis E virus,the natural history,epidemiology and medical experts' experience,pig-pig and pig-human transmission dynamics model was constructed.The parameters of the model were estimated based on literature,expert consultation and field investigation.The VENSIM software was used to simulate the epidemic situation with or without intervention measures,and to evaluate their effectiveness.Results(1)The average direct,indirect and total economic burden of 862 cases of hepatitis E patients were ?16,100,?4,300 and ?20,400,accounting for 49.84%,14.02% and 64.05% of PCDI respectively.The economic burden of men was higher than that of women(p<0.001).There were statistically significant between different regions about the economic burden of patients with hepatitis E(p<0.05),and the one in Yancheng city was the highest.Multivariate analysis showed that the direct economic burden of inpatients with hepatitis E was affected by disease history and course of disease(p<0.05),while the total economic burden was influenced by variables such as age,disease history,and course of disease(p<0.05).The EQ-5D utility value of 862 patients with hepatitis E was 622.28 QALY with an average of 0.72 QALY.The EQ-VAS score was 57,297 points,with an average of 70.00 points.There was a positive correlation between EQ-5D utility value(QALY)and EQ-VAS score(P<0.001).(2)The susceptible-infection-removed(SIR)model of pig to pig infection was constructed.The SIR model with birth,slaughter and environmental factors could better reflect the process of hepatitis E transmission in pigs.The results of simulation showed that environment factors was the most important affecting the transmission of hepatitis E.Sensitivity analysis showed that the transmission coefficient of HEV contacting pigs in the environment was the most sensitive.(3)The pig-pig,pig-human dynamic model(susceptible-exposed-asymptomatic infectiousremoved-contamination,SEAIRC)were constructed.Compared with the actual data,the SEAIRC model has a goodness of fit of 0.786.After evaluating the effects of different interventions(vaccinations,removing pig group,cutting water or food),the results demonstrated that removal of pig group transmission and vaccination were two measures to effectively control the hepatitis E epidemic,followed by measures to remove water or food transmission media.Probabilistic sensitivity analysis found that the infection coefficient caused by contact between occupational groups and pigs was the most sensitive.ConclusionsThe burden of hepatitis E in Jiangsu Province was severe and affected by region,gender and age.The system dynamic model showed that strengthening the management of pigs and vaccination of population helped to prevent and control the spread of hepatitis E.