The physiological changes of the human body due to aging can reduce body composition, nervous functions, homeostatic functions, energy production, regulating functions, etc., even though an elderly person does not have a specific disease. These problems can cause gait disorders, cognitive disorders, sensory disorders, and so on . These problems are also easily overlooked by natural changes related to aging, and often lead to a lack of healthcare, which may be needed for diagnosis and treatment. Unfortunately, these unmet healthcare needs also lead to further physical, mental, and social dysfunctions among older adults, thus resulting in a poorer health status and increased health inequalities .
This study analysed factors related to the unmet healthcare needs of older adults based on their KHPS data.
In this study, 94.4% of elderly people had chronic diseases, 15.8% had a disability, 10.0% had depressive symptoms, 49.5% had visual impairment, 29.7% had hearing impairment, 10.1% had memory impairment, and 4.8% had decision-making impairment. In France, 98.0% had at least one chronic health problem or disease, 20.0% had depressive symptoms, 10.2% had visual impairment, and 3.6% had hearing impairment .
Unmet healthcare needs were found in 17.4% of the participants. Of the unmet healthcare needs, we revealed that 9.2% were due to economic hardship classified as accessibility, 1.7% due to scheduling conflict classified as availability of service, and 6.5% due to other reasons including acceptability of available services. Previously, this number was reported as 0.4–13.8% for the general population  and 12.2–13.1% for the adult population [22, 23]. In Greece, the proportion was higher (26.3%) . Consistently, an analysis of the KHPS in 2012 revealed a prevalence rate of 16.9% , and the elderly had the highest amount of unmet healthcare needs among all age groups.
In a Canadian study, adults reported problems of availability of services (54.9%), followed by acceptability of available services (42.8%) and accessibility (12.7%) .
Like past results, we revealed that economic hardship (accessibility) was a key reason for unmet healthcare needs [24, 25]; however, in past studies of young adults, ‘waiting time is too long (availability of services)’  and being ‘too busy (acceptability of available services)’  were deemed more vital reasons than economic hardship (accessibility). Perhaps, economic hardship is the primary concern among the elderly because of a low income due to retirement; therefore, money is spent on maintaining livelihood rather than medical expenses.
As in previous studies, the following variables were key factors associated with unmet healthcare needs: sex [2, 3, 12, 14], age [12, 15, 24, 26], spouse [2, 15], education [12, 18], types of health insurance , household income [12, 18, 24], self-perceived health status [3, 12, 18, 24, 26], disability , depressive symptoms [12, 15], and regular family doctor [2, 3]. Contrastingly, in Hwang and Choi , disability did not affect the unmet healthcare needs of the elderly. Other studies also found significant associations regarding private health insurance, economic status, current smoker, and chronic disease variables [15, 18, 24, 26]; while some others reported results similar to this study [3, 12, 15, 26]. These conflicting results suggest that it is necessary to establish systematic reviews or meta-analyses for these factors.
Visual and hearing impairment of the elderly has been reported to have a negative impact on depression and cognitive functioning  and functional state . Visual and hearing impairment may affect overall physical health status as well as restraint and emotionality. In general, visual and hearing impairments are often recognized as common processes of aging and are thus easily overlooked. These problems are both mediators and direct factors in unmet healthcare needs. To minimize the health problems that may arise because of visual and hearing impairments, it is necessary to develop a policy to improve the use of medical care for periodic screening and treatment. Memory impairment and decision-making impairment can also be approached in a similar fashion since they have a negative impact on medication compliance  and self-care . Specifically, older adults with memory and decision-making impairments are less likely to be treated than those without such impairments because of poor compliance with healthcare problems.
Strengths and limitations
It was meaningful to investigate the relationship between health-related factors, socioeconomic factors, and unmet healthcare needs among older adults using the KHPS, which provided representative data from a large population. In addition, it was meaningful to consider socioeconomic, health-related, and aging factors. However, to get a deeper understanding of the unmet healthcare needs of elderly people, it is necessary to use diverse research methods such as focus group interviews and in-depth interviews.