This study aimed to evaluate the value of medical care use according to travel costs for patients with mild diseases who visited tertiary hospitals to devise measures to alleviate patient concentration. The analysis revealed that travel costs for patients with mild disease were higher in Jeollanam-do, Daejeon Metropolitan City, and Gyeongsangnam-do. Jeollanam-do and Gyeongsangnam-do, where travel costs appeared relatively high, are located in the southernmost regions of Korea, showing a similar context to the research results suggesting that transportation and medical costs would increase as the distance to visit a medical institution increases more [38, 39]. However, Daejeon Metropolitan City showed high travel costs despite its relatively short distance. This implies that Ajou University Hospital, located at the southernmost point among the tertiary hospitals in the metropolitan area, is also attracting patients from Daejeon Metropolitan City who visit medical institutions to use multiple medical services. However, regions with high travel costs have one similarity, that is, a lack of medical institutions. Jeollanam-do has the largest number of medically vulnerable areas as 17 spots and is also in a situation where the medical departments of public medical institutions are being abolished owing to a shortage of medical personnel. Additionally, Daejeon Metropolitan City is experiencing a serious medical vacancy, as some specialists are not assigned by the locally responsible medical institution that is supposed to provide essential medical care services. In Gyeongsangnam-do, there is a shortage of public medical centers owing to incidents such as the abolition of the Jinju Medical Center, resulting in high utilization rates at tertiary hospitals in other regions. As such, the lack of medical institutions and manpower in the region may induce problems in medical equity, and continuous patient breakaway leads to difficulties in operating primary and secondary medical institutions in the region, making it a medically vulnerable area, which may be repeated in a vicious cycle [40, 41].
Examining the results of the comparative analysis of travel costs according to disease and demographic characteristics, no statistically significant differences were found in all variables when medical costs were included. This finding suggests that travel and time costs are more valuable than medical costs when patients with mild disease choose to visit tertiary hospitals. The comparative analysis of travel costs, excluding medical costs, revealed statistically significant differences for all variables. Travel costs were the highest for diabetes, followed by dementia, cerebrovascular disease, and hypertension. This means that patients with diabetes, dementia, and cerebrovascular disease are more likely to visit tertiary hospitals in areas with greater access costs than patients with hypertension. This supports research that compares per capita chronic disease outpatient medical expenditures by region and finds that overall, diabetes and hyperlipidemia patients have higher medical expenditures than hypertension patients, that diabetes patients have a higher preference for tertiary hospitals than hypertension patients, and that diabetes patients are more likely to use tertiary hospitals once they have used them [42, 43]. This may be because patients with hypertension, unlike patients with diabetes, dementia, and cerebrovascular disease, prefer to manage their disease by taking medication for a long period to visit a medical institution to receive medical treatment.
In summary, travel and time costs are taken into account in the use of tertiary hospitals by patients with mild diseases, and it can be said that patients with diabetes, who are relatively loyal to tertiary hospitals, bear more travel and time costs than patients with dementia, cerebrovascular disease, and hypertension. For diabetes, like hypertension, early detection and proper management with medication can prevent complications from occurring, so it is important to focus on primary care centers in the community. However, unlike hypertension, which is relatively easy to screen and diagnose, diabetes, which is diverse and expensive, requires more detailed measures to support or manage it differently in primary healthcare chronic disease management projects [44]. Therefore, to encourage patients with mild diseases to switch from tertiary hospitals to primary care, positive discussions are essential to determine the priorities according to the type of mild disease.
Meanwhile, travel costs according to demographic characteristics were higher for men than for women. Further, travel costs were higher for those under 65 years of age than for those 65 years or older. This is consistent with the existing research results, suggesting that men tend to visit medical institutions in distant areas but spend relatively lower medical costs than older women [45–47]. Furthermore, in terms of insurance type, travel costs were higher in medical aid type 2, medical aid type 1, and health insurance subscribers. This indicates that the low-income bracket (medical beneficiaries) visit medical institutions located far from their residence, which is similar to existing research results suggesting that the lower the economic status, the lower the accessibility to medical care because of a lack of medical resources in the region [48, 49].
Overall, it can be concluded that among the patients with mild diseases who use tertiary hospitals, medical beneficiaries, who are socially vulnerable, incur more travel and time costs than health insurance subscribers. Considering the previous finding that travel costs, including medical costs, were not significant, this can be interpreted as a net function of the Korean health insurance system providing equity in access to healthcare by easing the burden of medical costs on medical beneficiaries. However, given the skewing of patients with mild diseases to tertiary hospitals, it is necessary to provide incentives to encourage medical beneficiaries with high out-of-pocket expenditures to use community healthcare [50, 51].
Examining the field-experience demand function derived according to the increase or decrease in distance and travel costs, the increased travel costs resulted in a statistically significant decrease in the outpatient visit rate for patients with mild diseases. This is consistent with existing research suggesting that because distance is inversely proportional to visitation rates, the greater the distance, the more visitation rates decrease [52, 53]. When visiting a medical institution, if the travel cost exceeded $77.07 (KRW 100,000), the number of patients in all regions declined below 1,000 people, and if it exceeded $462.43 (KRW 600,000), the number of patients in all regions declined below 100. This is probably because the development of transportation, including the KTX, has made it easier to travel between regions at a lower cost, making it possible to choose medical institutions outside the local community. Accordingly, to enable mild disease management within the local community, it is necessary to expand medical institutions that can provide a value of at least $77.07 and up to $462.43.
When comparing the economic value per capita assessed for each type of patient, hypertension, diabetes, dementia, and cerebrovascular disease are the highest, and hypertension and diabetes are more valuable to individuals than dementia and cerebrovascular disease. In addition, the total economic value of Ajou University Hospital by type of patient is higher for diabetes, cerebrovascular disease, hypertension, and dementia, in the same order as the number of visits by type. In sum, it was found that the value of using the tertiary hospital is higher for patients with hypertension and diabetes, which can be managed with medication in the community, than for cerebrovascular disease and dementia, which are more severe among chronic diseases. Furthermore, when comparing the total economic value of hypertensive and diabetic patients, the difference was 7.8 times that of hypertensive patients. This suggests that patients with diabetes or hypertension who can be managed in the community are more likely to prefer to use a tertiary hospital, which means that the core function of tertiary hospitals, medical care for severe diseases, is not adequately provided. In particular, in the case of diabetes, which has the highest total economic value, it is judged that it is due to various and expensive test methods compared to other mild diseases. In addition, the rate of diabetes-related tests and complication screenings in tertiary hospitals was 1.8 times higher than in primary care centers, indicating a higher amount of economic value compared to other mild diseases.
In conclusion, the high proportion of patients with less severe diseases utilizing tertiary hospitals indicates that the core function of tertiary hospitals, medical treatment of severe diseases, is not being adequately carried out, and unnecessary medical expenditures are being incurred due to the use of advanced medical services. In particular, from the perspective that the higher the economic value of using a tertiary hospital, the higher the preference for using a tertiary hospital, the most preferred targets of tertiary hospitals are medical beneficiaries with diabetes among men under the age of 65 living in medical underdeveloped areas. Therefore, it is necessary to prepare policies that consider the characteristics of healthcare utilization by region, disease, and individual characteristics in order to induce healthcare utilization in the community and activate the healthcare delivery system leading to the primary, secondary, and tertiary levels.