Comparisons of the Severity between the Kidney and Non-Kidney Disabled Persons by the Number of Chronic Diseases, Out-of-Pocket Expenditure, and Quality of Life: using Korea Health Panel

Background: Due to End-Stage Renal Disease, patients who have received dialysis for more than three months or who have already received a kidney transplant are eligible for registration as the Kidney Disabled in Korea. This study aimed to identify the severity between the Kidney and Non-Kidney Disabled by the number of chronic diseases, out-of-pocket expenditure, and quality of life. Methods: This study used the Korean Health Panel from 2009 to 2013. We compared the number of chronic diseases, out-of-pocket expenditure, and quality of life between the Kidney and Non-Kidney Disabled. The Non-Kidney Disabled included heart, liver, respiratory organ, colostomy or urostomy, and epilepsy. Chi-Square, t-test, and ANCOVA were conducted, and then the trends for five years were explored through panel analysis. Results: Of the 308 subjects, 136 (44.2%) had Kidney Disability and 172 (55.8%) had Non-Kidney Disabilities. The number of chronic diseases was 4.7 in the Kidney Disabled and 3.3 in the Non-Kidney Disabled (P<0.001). The annual out-of-pocket expenditure for the Kidney Disabled was $1,310 and that for the Non-Kidney Disabled $812 (P<0.001). Today’s subjective health status for the quality of life (from the worst 0 points to the best 100 points ) was 48.9 for the Kidney Disabled and 60.4 for the Non-Kidney Disabled (P<0.001). In addition, the five years trends for the number of chronic diseases, annual out-of-pocket medical expenditure, and quality of life also differed between the Kidney and the Non-Kidney Disabled (P<0.01). Conclusion: The Kidney Disabled was more serious than the Non-Kidney Disabled in the aspect of the number of chronic diseases, the out-of-pocket medical expenditure, and quality of life. Therefore, it is necessary to consider greater interest in the health care of the Kidney-Disabled people in terms of equity.


Background
In addition to inequality in modern society, the equity of health is deepening further, which could put more emphasis on health policies. In order to achieve the policy goal of inclusive welfare management, the health level of the disabled should be a major research task. Nevertheless, it is rare to study the health of people with disabilities, especially those with internal-organ disabilities. According to the law on the welfare of the disabled, it means that disabled people have physical or mental disabilities and are significantly restricted in their daily lives or social activities. Types of physical disorders are externalphysical and Internal-organ disabled. In Korea, patients with end-stage renal disease (ESRD) who have received dialysis for more than three months or kidney transplantation (KT) can register as the Kidney Disabled.
The ESRD has not only more severity than other chronic diseases but also more medical expenditure absolutely in the world. Renal replacement therapy (RRT) including peritoneal dialysis (PD), hemodialysis (HD) or KT is essential for ESRD. Besides, the key risk factors of ESRD such as diabetes and hypertension have been increased [1]. The prevalence of ESRD among diabetes and hypertension had over 4-10 times in the general population [2][3][4]. ESRD will be increased more with the aging population and increasing lifespan. Medical expenditure of ESRD will be increased more and more and will be a big problem with their remaining life. Therefore, it is possible to predict that the Kidney Disabled persons have a worse degree of severity, medical expenditure, and quality of Life (QOL) than those of Non-Kidney Disabilities.
The increase in ESRD is expected to increase the number of people with kidney disabilities in the future. ESRD, in particular, has already experienced physical and mental crises due to its pathologic nature. They have been frustrated by long-term disease management and high medical spending. Also, due to health difficulties, only about 22% of HD and 36% of PD patients worked full-time [5]. The subjects have financial difficulties, and the national burden is increasing. The registered disabled on the act receive a variety of medical benefits compared to the general population. In Korea, people receiving Medical Aid (MA) in general population is about 3%, but the disabled persons receiving MA is about 30%.
The burden of government is also increasing more and more.
Public awareness of the seriousness of ESRD is also relatively low compared to cancer and stroke. Compared to the other internal-organ disabled people, information on the Kidney Disabled is relatively poor because of little studies [6]. Therefore, various medical welfare programs suitable for the Kidney Disabled are not actively applied. Also, there have been few studies on multimorbidity, annual OOP expenditure, and QOL for the Kidney disabled [5]. So, we aimed to identify the relative severity between the Kidney and Non-Kidney Disabled by the number of chronic diseases, annual OOP expenditure, and QOL, using Korea Health Panel (KHP) from 2009 to 2013.

Data source
The study used KHP data co-organized by the Korea Institute for Health and Social Affairs (KIHASA) and the National Health Insurance (NHI) Corporation. KHP data is representative national data that provided scientific data on medical service use, expenditure, health behavior, QOL, etc. The survey was launched in 2008, and further surveys such as health behaviors and QOL were launched in 2009. The subjects were selected by stratification multistage random sampling and have examined the same or slightly modified variables every year to date. The data are opened to the public for various policy decisions after a data wash period of approximately three years.
This study analyzed longitudinal KHP data without weight. This is because the biasness will be reliable than unbiasness of samples, as the number of people with Internal-organ disabled is small, but all Internal-organ disabled was included. In addition, it is expected that factual identification of subjects since the attrition of the subjects may be due to actual health problems.
We received official data from KIHASA from 2008 to 2013 for this study in 2016. Therefore, we analyzed five years of data from 2009 to 2013, when QOL began to be investigated.
This data was officially received by the Agency Review Board (KIHASA 2016-01).

Data collection
The KHP questionnaire consisted of a household and a household member component. All the variables were examined by a skilled interviewer who visited the family for face-toface interviews using a computer. In particular, for the accuracy of annual medical use and expenditures, the subject was recorded in the medical diary prepared specially for medical use and expenditures. To this end, the NHI and KIHASA trained the subjects how to store records and receipts.

Analytic variables and study subjects
Variables used in this study included types of disabilities, gender, age, marriage history, medical assurance, economic activity, number of chronic diseases, annual OOP medical expenditure, and today's subjective health status as QOL (EQ VAS) [7].
Subject to this study are 308 people with the Internal-organ disabled among the panel subjects for a period of five years from 2009 to 2013. They were only 6.5% of the 4,732 disabled people in the KHP data in the same period. The disabled in the KHP was registered under the Act on the Welfare of Persons with Disabilities. Among them, Kidney disability consisted of dialysis (n = 115) and KT (n = 21) and Non-Kidney disability included heart (n = 25), respiratory organ (n = 43), liver (n = 5), colostomy or urostomy (n = 32), and epilepsy (n = 67). As there are rare Internal-organ disabled, we classified the subjects as the Kidney and Non-Kidney Disabled (heart, respiratory organ, liver, colostomy or urostomy, and epilepsy) for clarity of the results. Because we focused on the distinct characteristics of those with Kidney Disabled among the Internal-organ disabled.
Also, the subject sizes for the two groups were different. But to know the factual phenomenon, we did not make the equal of subjects through matching.

Statistical analysis
The socio-demographic characteristics of the Kidney Disabled and Non-Kidney Disabled were identified through descriptive statistics, t and Chi-Square test. Through ANCOVA, the number of chronic diseases, annual OOP medical expenditure, and today's subjective health status as QOL points (EQ VAS) were determined by comparing the Kidney Disabled and Non-Kidney Disabled. The covariates such as gender, age, marital status, and economic activity were adjusted.
In addition, through the linear panel analysis of fixed effect, five years variation in the number of chronic diseases, annual personal OOP expenditure, and the today's subjective health status as QOL was presented in locally weighted scatter-plot smoother (LOWESS) curve. The statistical significance was then presented after control of the sex and age.
The variance of each panel model was also analyzed with a saturated or main effects model with a compound symmetry covariance matrix, depending on the interaction effect.
All expenditure (South Korean Won, KRW) were calculated in USD dollars ($) as of July 1, 2009 (1$ = 1,258.59 KRW) [8]. All analyses were conducted after excluding missing data using SAS 9.4 (SAS Institute, Cary, NC, USA). P-values of less than 0.05 were regarded as statistically significant.
Definitions of terms 7 The Internal-organ disabled, Kidney or Non Kidney disabled The Internal-organ disabled means people with organ disabilities: kidney, heart, liver, respiratory organ, colostomy or urostomy, and epilepsy. People with internal-organ disabilities need to receive treatment continuously and are hard to get a job due to social prejudice, and often suffer from poverty. So, the disabled are registered under the Act on the Welfare of Persons with Disabilities. Today's subjective health status as single summary QOL points (EQ VAS) EQ visual analogue scale was mark health status on the day of the interview on a vertical scale with endpoints of 0 and 100. There are notes at both ends of the scale that the bottom rate (0) corresponds to " the worst health you can imagine", and the highest rate (100) corresponds to "the best health you can imagine". A well-known limitation of visual analogue scale is end-of-scale bias that respondents are less likely to use the extreme ends of the scale for rating their health status. However, it is still useful and the simplest direct method for valuing health-related quality of life. [10] Medical Social Security program In Korea, Medical Social Security consists of NHI and Public MA. NHI is a compulsory system for social security net. Ninty-seven% of Korean people have NHI obligatory.
Koreans should pay insurance premiums to NHI according to their income and asset levels.
Their co-payment has been from 20% up to 60% of the total fee for each medical service [11,12].
Meanwhile, MA supports the lowest income group or the persons with an incapacity for maintaining their life. They pay small co-payment in admission (zero to 10% of the total fee) and in OPD visit of clinic or hospital ($0.95 to 15% of total fee) less than those of NHI [12].   2) Kidney disability consisted of dialysis (n=115) and KT (n=21) patients.
4) The covariates were gender, age, marital status, and economic activity.

Today's subjective health status as QOL (EQ VAS)
The result showed that among the best points (100), the average response points for the Kidney Disabled was 48.9, which was lower than 60.4 for the Non-Kidney disabled (Table4). 1) Kidney disability consisted of dialysis (n=115) and KT (n=21) patients.
3) The covariates were gender, age, marital status, and economic activity.

Discussion
ESRD is a disease that accumulates uremic toxin due to almost no kidney function. ESRD patients will continue to increase exponentially with aging populations and an increase in the incidence of chronic diseases such as diabetes and high blood pressure [5]. ESRD is managed by RRT such as KT or dialysis. So, the patients' lifespan will be also increased more and more [5]. In Korea, the number of patients receiving RRT increased to 75,042 in 2013 and 80,674 in 2014 [13,14]. Therefore, the Kidney Disabled who receive KT or dialysis with ESRD will increase further in the future, and the burden of the nation will also increase.
ESRD is a chronic and severe disease that requires long-term care with high-cost medical care such as RRT. ESRD patients are severely limited to full-time activity over a long period of time. As a result, only about 22 percent of HD and 36 percent of PD patients work full-time [5]. Nevertheless, studies on the personal OOP burden and the QOL caused by ESRD are rare, and studies on the health severity of the Kidney Disabled due to ESRD are even very rare. Therefore, this study targeted comparisons of severity between the Kidney Disabled and Non-Kidney Disabled by the number of chronic diseases, annual OOP medical expenditure, and the QOL.
In our research, 28.7% of the Kidney Disabled had MA lower than 35.5% of the Non-Kidney Disabled. The OOP medical expenditure burden in NHI was higher than MA. In addition, the economic activity of the Non-Kidney Disabled was 33.9% while only 12.5% of the Kidney Disabled. It reflected that the latter subjects required a lot of time to treat and had a quite difficult situation to sustain a job. In the previous study, it was similar that only a small percentage had economic activity in ESRD [15][16][17][18]. Therefore, it needs to consider the medical welfare policy about OOP expenditure in the Kidney Disabled, especially than others. It needs not the only improvement about the negative perception for the disabled, but also labor policy to ensure livelihood security through national benefit enforcement for the employer to employ the kidney disabled.
Twenty-Five percent of the U.S. adult population had at least 2 chronic diseases, which were the critical etiology of mortality [19]. Patients with ESRD had a larger comorbidity burden [20]. It was similar to our study results. In this study, the number of chronic diseases was 4.7 in the Kidney Disabled and 3.3 of the Non-Kidney Disabled (P<0.001). In addition, trends over five years in the number of chronic diseases between the Kidney Disabled and Non-Kidney Disabled also showed a significant difference (P<0.01).
In other country, Medicare beneficiaries with ESRD would have approximately twice OOP expenditure than that of Medicare in Non-ESRD [21]. In our study, annual OOP medical expenditure was $1,310 in the Kidney Disabled and $832 in the Non-Kidney Disabled (P<0.001). Trend over five years of annual OOP medical expenditure showed a significant difference between the Kidney Disabled and the Non-Kidney Disabled (P<0.001).
In the previous study, the QOL of ESRD was lower than Non-ESRD, especially the QOL in five domains index including Mobility, Usual Activities, and Pain/Discomfort [22].  [23][24][25]. Therefore, it is necessary to consider greater interest in the health care of the Kidney-Disabled people in terms of equity.