Effects of Socioeconomic Status and Residence Areas on Long-term Survival in Patients with Early-onset Dementia: The Korean National Health Insurance Service Database Study

Abstract

Background: Early-onset dementia (EOD) is still insufficiently considered for healthcare policies. We investigated the effect of socio-environmental factors on the long-term survival of patients with EOD. Methods: This retrospective cohort study utilized the Korean National Health Insurance Database from 2007 to 2018. We enrolled 3,825 patients aged 40 to 65 years old with all types of dementia newly diagnosed in 2009 as EOD cases. We defined socioeconomic status using the national health insurance premium (NHIP) levels. Residential areas were classified into capital, metropolitan, city, and county levels. All-cause mortality was the primary outcome. Kaplan-Meier curves and log-rank tests were employed. Further, Cox-proportional hazards models were established. Results: The mean survival of the fourth NHIP level group was 96.31 ± 1.20 months, whereas that of the medical-aid group was 85.53 ± 1.30 months (P < 0.001). The patients living in the capital had a mean survival of 95.73 ± 1.34 months, whereas those living in the county had 89.66 ± 1.75 months (P = 0.035). In the Cox-proportional hazards model, the medical-aid (adjusted hazard ratio [aHR], 1.67; P < 0.001), first NHIP level (aHR, 1.26; P = 0.012), and second NHIP level (aHR, 1.26; P = 0.008) groups were significantly associated with a higher long-term mortality risk. The capital residents exhibited a significantly lower long-term mortality risk than did the county residents (aHR, 0.82; P = 0.041). Conclusion: Socioeconomic status and residential area are associated with long-term survival in patients with EOD. This study provides a rational basis for establishing a healthcare policy for patients with EOD.