P1545LOW SOCIOECONAMIC STATUS INCREASES MORTALITY RISK IN KOREAN MAINTENANCE HEMODIALYSIS PATIENTS: A LONGITUDINAL COHORT STUDY USING HEMODIALYSIS QUALITY ASSESSMENT DATA

Abstract

Abstract Background and Aims The number of hemodialysis (HD) patients and their medical expenses are growing rapidly in Korea due to entry into aging society and accompanying diseases such as diabetes and hypertension. Whether low socioeconomic status (SES) affect poorer HD survival is controversial with most reports come from the USA. Therefore, this study was performed to evaluate the effect of SES upon mortality in Korean maintenance HD patients using periodic HD quality assessment data. Method The HD quality assessment has been performed periodically by Health Insurance review and Assessment Service (HIRA) since 2001. We used 4th and 5th HD quality assessment data from the year of 2013 and 2015 respectively for collecting demographic and clinical data. The 4th survey was a sample survey while the 5th survey was a complete enumeration survey. We also collected data on patient comorbidity using the diagnosis codes from the health insurance claims database. The mortality data was collected until Dec 2017. As a proxy indicator reflecting SES, we classified subjects as a Medical Aid (MA) recipients (“low” SES) or a National Health Insurance (NHI) beneficiary (“middle/high” SES). We analyzed mortality risk based on SES using Cox proportional hazard model. Results A total of 21,786 HD patients from 4th survey and 35,454 HD patients from 5th survey were included in the analysis. The ratio between NHI beneficiary and MA recipient was 76.7% versus 23.3%. Mean age of the subjects was 59.0 years old in 4th survey and 60.3 years old in 5th survey. The MA recipients were younger and showed higher proportion of male, shorter duration of HD, lower body mass index (BMI), higher systolic and diastolic blood pressures before HD compared to the NHI beneficiary. The NHI beneficiary demonstrated higher proportion of diabetes, hypertension, cerebrovascular accidents, and dementia compared to the MA recipients. Two groups did not differ in dialysis efficiency presented as single pool Kt/V. A total of 7,173 deaths occurred in 2013 participants, while 7,306 deaths occurred in 2015 participants. After adjusting for age, gender, Charlson’s comorbidity index, BMI, presence of atrial fibrillation, serum albumin, and serum creatinine, MA recipients showed significantly higher mortality risk compared to the NHI beneficiary (hazard ratio 1.162; 95% confidence interval 1.092-1.237, p<0.001 in 4th survey and hazard ratio 1.078; 95% confidence interval 1.013-1.146, p=0.017 in 5th survey). Conclusion Low SES independently increased mortality risk in Korean maintenance hemodialysis patients.