Association Between Health Insurance Type and Survival Outcomes: Insight Into the Impact of Socioeconomic Disparities in the Postoperative Outcomes of Abdominal Aortic Aneurysm in Korea

Abstract

Background: Abdominal aortic aneurysm (AAA) is associated with a high mortality rate if left untreated, and medically vulnerable populations experience significant disparities in treatment and outcomes. We investigated the characteristics and treatment outcomes of AAA according to the insurance type (i.e., National Health Insurance [NHI] and Medical Aid) in South Korea using the nationwide health insurance database.

Methods: From 2002 to 2019, a total of 15,065 patients underwent either open aneurysm repair (OAR) or endovascular aneurysm repair (EVAR). The primary outcome was AAA-related mortality, with follow-up conducted until death or December 31, 2019, for those without mortality records. Mortality was evaluated using Kaplan-Meier curves and an adjusted Cox proportional hazards model to identify independent risk factors for AAA-related mortality. Propensity score matching (PSM) was employed using relevant covariates to achieve a 1:10 match between the NHI and Medical Aid groups.

Results: Among the EVAR patients, the rate of AAA-related mortality was significantly higher in the Medical Aid group compared to the NHI group (P < 0.001). After adjusting for covariates, the difference in AAA-related mortality rates between the two insurance groups remained statistically significant. No significant difference was found between the two groups among OAR patients (P = 0.727). Factors such as age, insurance type, hypertension, diastolic blood pressure, hemoglobin levels, and glomerular filtration rate were significantly associated with AAA-related mortality in the unadjusted multivariable analysis among the EVAR patients. Specifically, Medical Aid patients had a 1.87-fold higher risk of AAA-related mortality compared to NHI patients. Notably, in the PSM cohort, multivariable analysis confirmed that insurance type remained a significant factor for AAA-related mortality in EVAR patients.

Conclusion: In patients undergoing EVAR for AAA, insurance type was independently associated with postoperative AAA-related mortality, with Medical Aid patients experiencing worse outcomes. In contrast, no significant difference in AAA-related mortality was observed between insurance types among patients undergoing OAR. These findings highlight the need to improve postoperative care and address outcome disparities in vulnerable populations undergoing EVAR.

Keywords: Abdominal Aortic Aneurysms; Endovascular Aneurysm Repair; Health Insurance; Healthcare Disparities; Mortality; Open Aneurysm Repair.

Fig. 1. Flowchart of the study population.

ICD-10 = International Classification of Diseases-10, OAR = open aneurysm repair, EVAR = endovascular aneurysm repair.

Fig. 2. Trends in surgery for abdominal aortic aneurysm and patterns by insurance type.

NHI = National Health Insurance, OAR = open aneurysm repair, EVAR = endovascular aneurysm repair.

Fig. 3. Comparison of long-term survival outcomes in abdominal aortic aneurysm patients based on surgical treatment and insurance type: unadjusted vs. age-adjusted analysis. (A) Unadjusted survival curve for all-cause mortality according to surgical treatment. (B) Age-adjusted survival curve for all-cause mortality according to surgical treatment. (C) Unadjusted survival curve for all-cause mortality according to insurance type. (D) Age-adjusted survival curve for all-cause mortality according to insurance type. (E) Unadjusted survival curve for AAA-related mortality according to insurance type. (F) Age-adjusted survival curve for AAA-related mortality according to insurance type.

The unadjusted survival curves are shown on the left, while the age-adjusted survival curves are displayed on the right. The difference in survival curves according to surgical treatment was statistically significant before adjustment but became non-significant after age adjustment. In contrast, the difference in survival curves according to insurance type remained statistically significant both before and after adjustment. OAR = open aneurysm repair, EVAR = endovascular aneurysm repair, NHI = National Health Insurance.

Fig. 4. Survival analysis of EVAR and OAR cohorts based on insurance type. (A) Unadjusted survival curve for AAA-related mortality according to insurance type in the EVAR cohort. (B) Unadjusted survival curve for all-cause mortality according to insurance type in the EVAR cohort. (C) Unadjusted survival curve for AAA-related mortality according to insurance type in the OAR cohort. (D) Unadjusted survival curve for all-cause mortality according to insurance type in the OAR cohort.

EVAR = endovascular aneurysm repair, AAA = abdominal aortic aneurysm, NHI = National Health Insurance, OAR = open aneurysm repair.

Fig. 5. Forest plot of multivariate Cox proportional hazard analysis: risk factors for abdominal aortic aneurysm -related mortality in endovascular aneurysm repair patients.

SBP = systolic blood pressure, DBP = diastolic blood pressure, ALT = alanine transaminase, GFR = glomerular filtration rate.

Fig. 6. Relative importance of variables for survival in multivariate Cox proportional hazard analysis on endovascular aneurysm repair patients.

GFR = glomerular filtration rate, DBP = diastolic blood pressure, SBP = systolic blood pressure, ALT = alanine transaminase.