IntroductionHand Foot and Mouth disease (HFMD) is an acute viral infection caused by a variety of enteroviruses that affect young children (aged less than 10 years), especially children less than 5 years old . Recently, there has been an increase in the number of children who go to daily childcare, and this seems to have an effect on shortening the cycle of major epidemics compared to previous years in Republic of Korea (ROK). Enteroviruses are highly contagious, so to prevent HFMD outbreaks and epidemics in ROK, new vaccination development is essential. However, the only HFMD vaccine (enterovirus 71) was developed and licensed for use only in China. A new HFMD vaccine needs to be developed and authorized for use in ROK.Government policies in ROK are in place to aid the development of a new HFMD vaccine so that it can be introduced into the national immunization program (NIP). However, introduction of a new vaccine program requires evaluation of cost-effectiveness. Therefore, the socioeconomic disease burden of HFMD in ROK needs to be estimated in advance.
1. Study populationData from the national sentinel surveillance and national health insurance systems reported from 2010 to 2014 were used. The assumption was made that all patients visited outpatient clinics or were hospitalized.Due to limitations in access to all data, randomly sampled insurance data were used from 1 million people who claimed medical compensation from the national health insurance organization. To extract HFMD cases, patients were selected whose main diagnosis in insurance data terms were B08.4 or B08.5 within the KCD-10 code.
2. Estimating the incidence of cases and deaths resulting from hand, foot and mouth diseaseThe estimation for number of HFMD cases and death in ROK was based on the annual occurrence rate of HFMD and was reverse calculated. We referred annual occurrence rates of HFMD from “KCDC Surveillance reports for infectious disease” from 2010 to 2014. Total number of patients who visited hospitals, especially the department of pediatrics were referred from the “Annual statistical reports of national health insurance system” from 2010 to 2014 .
3. Models for calculating economic disease burden of HFMDSince HFMD is an acute viral infectious disease and, disease progression and recovery occurs in a short period of time (less than 1 year), methodology was based on incidence rather than prevalence.Figure 1 shows the proposed formula for calculating economic costs due to HFMD . Moreover, direct costs and indirect costs are considered, with several components which are described in Figure 2.From available data in the health insurance system, total medical costs for patients who visited outpatient clinics or who were hospitalized due to HFMD were used. The medical costs for prescribed medicines due to HFMD were calculated by multiplying annual total number of HFMD patients by the average number of prescribed days and average daily medical costs for the prescribed medicines.
ResultsIn Table 1, the estimated number of HFMD cases and deaths in ROK between 2010 and 2014 are listed and show the number of HFMD cases was mainly influenced by epidemics. Estimated number of deaths due to HFMD ranged from 1 to 3, which seems rational considering the low death rates in young children in ROK. Cost due to premature deaths rose from 2.3 million to 7.2 million from 2010 to 2014.In 2008 and 2009, 5,870 and 6,338 HFMD cases were reported to the national surveillance system in ROK . The number of HFMD cases was mainly influenced by whether there was a large epidemic or not in that year. However, the estimated numbers of HFMD cases between 2010 and 2014 seem to be similar to the figures in 2008 and 2009 . Estimated number of deaths due to HFMD ranged from 1 to 3 which seemed reasonable considering the low death rates in young children in ROK. It is consistent with the fact that the cumulative number of deaths from HFMD was 9 until 2016.Table 2 shows referred values calculated for direct non-medical costs and indirect costs for transportation and caregiving. Estimated indirect costs of caregiving were calculated in 2 ways. By taking the average salary of caregivers and parents or relatives, based on gender, where a range of indirect costs were observed. In the case of caregiving by families, according to caregiver’s gender and contribution to the household income (e.g. 100% or 25%), indirect costs for caregiving resulted in different values. Where male caregivers contributed more, indirect costs for caregiving were higher due to gender differences in average salaries per hour.From 2010 to 2013, instead of average daily hospital visits or admitted period, the total number of hospital visits or annual admitted periods from health insurance data was adapted because it was not possible to obtain the exact number of total hospital visits or admitted period for 2014, so an estimated average daily hospital visits or admitted period per patient was used and multiplied by the total annual number of patients.In Table 3, socioeconomic disease burden of HFMD in ROK between 2010 and 2014 is shown. The economic costs had not increased annually since the total number of HFMD cases depended on whether there were more outbreaks, or a large epidemic in that year. Even though increased health insurance fees and inflation rates had an effect on economic costs, the differences in total number of HFMD cases offset the impact. The total individual patient costs during the period of infection with HFMD were significantly different between 2010 and 2014 as determined by ANOVA (p 0.021).The estimated total economic costs of HFMD in ROK between 2010 and 2014 ranged from 80.5 to 164.2 million USD. They were similar to the costs from hepatitis A infection which was previously treated as enterovirus infection and more than the costs from rotavirus infection. However, they were less than the socioeconomic burden of irritable bowel syndrome (Table 4). The 4 components (direct medical costs from outpatient clinics or hospitals, costs for the prescribed medicines, direct non-medical costs, cost for caregiving) consisting the socioeconomic burden of HFMD were revealed to be related to each other statistically by partial correlation analysis, after putting year as the control variable (Table 5).
DiscussionIn the Western Pacific region, widespread epidemics of HFMD have been reported in many countries including Australia, China, Japan and the ROK . HFMD cases in ROK were mostly reported in summer and was similar to other Asian countries having comparable climates such as China and Japan .Therefore, during the peak period in summer, the incidence of complaints about sick children from parents and the media is heightened. HFMD seems to increase social concern after large epidemics that mostly affect young children, resulting in parents’ loss of work due to caregiving. In our model, we calculated the costs of caregiving adapting both ways of caregiving.Since caregivers hired by parents of sick children tend to be paid less than the average salary of parents, the costs for hiring caregivers were estimated to be lower. Previously hepatitis A virus was classified as an enterovirus, since it shared common characteristics. Therefore, the socioeconomic disease burden of HFMD was considered to be similar to that of hepatitis A virus. Most of the estimated socioeconomic disease burden of HFMD arises from the costs for caregiving. Therefore, the high socioeconomic concern for HFMD epidemics seems to be mainly due to the loss of labor and the resulting opportunity costs. There may be a need for new policies to make up for the labor loss, such as making it easier to hire caregivers by compensating the costs and providing systematic support for emergency, short-term hiring. Although we calculated the average increasing rate for socioeconomic disease burden of HFMD, the costs fluctuated yearly depending on the size and number of outbreaks. The budget for preparing and responding to national HFMD epidemics has to be changed to allow flexible responses according to the situation. In addition, 4 components that contribute to the socioeconomic burden of HFMD (direct medical costs from outpatient clinics or hospitals, costs for prescribed medicines, direct non-medical costs, and costs for caregiving), were revealed to be statistically related to each other, since they are all dependent on the number of HFMD cases in a year. In other words, if a new vaccine for HFMD was to be developed in the future, it may be a useful strategy to decrease these 4 components at the same time.Although the current study estimated socioeconomic disease burden of HFMD and compared it with those of other similar diseases such as rotavirus and hepatitis A virus infection, several assumptions were made and calculations were based on average values resulting in a less precise estimation.