Lower Income Associated with Greater Mortality Risk in Chronic Liver Disease

Findings from a recent study are shining light on socioeconomic disparities in chronic liver disease, calling attention to the impact of income on mortality risk in individuals with nonalcoholic fatty liver disease (NAFLD) and viral hepatitis.¹

The analysis of 1999–2018 National Health and Nutrition Examination Surveys (NHANES) data revealed lower-income, foreign-born, and racial/ethnic minority groups were disproportionately represented among those with chronic liver disease, with individuals with chronic liver disease and lower income having twice the mortality risk compared to their higher-income counterparts.¹

A progressive deterioration of liver function affecting more than 4 million US adults, the most common etiologies of chronic liver disease are alcohol-associated liver disease, NAFLD, and viral hepatitis. Treatment seeks to stop the progression of the disease and complications, generally requiring prompt detection in order to prevent progression to cirrhosis and improve outcomes. However, despite known socioeconomic differences in the prevalence of liver disease, less is known about the impact on survival.^2,3

“Nationally representative data on mortality outcomes of individuals with chronic liver disease by income levels are sparse,” Mindie Nguyen, MD, a professor of medicine at Stanford University and a transplant hepatologist at Stanford University Medical Center, and colleagues wrote.¹

To evaluate the long-term mortality of people with chronic liver disease by income level and to investigate the association with mortality, investigators conducted a retrospective analysis of a population-based sample of persons with CLD NHANES data from 1999–2018. In the present study, chronic liver disease was defined as viral hepatitis, NAFLD, and alcohol-associated liver disease.¹

Viral hepatitis infection was defined as having either current or a history of HBV or HCV infection, while NAFLD was defined as a US fatty liver index of >30 in the absence of HBV and HCV infection and significant alcohol use (>2 drinks/day for men or >1 drink/day for women). Investigators defined alcohol-associated liver disease by a history of significant alcohol use (>3 drinks/day for the past 12 months for men and >2 drinks/day for the past 12 months for women) but no HBV or HCV infection in the presence of elevated liver enzymes levels and in the absence of a total bilirubin level >3 mg/dL.¹

Investigators conducted supplemental analyses based on the NHANES family income-to-poverty ratio, an index developed using the Department of Health and Human Services poverty guidelines. They grouped individuals into lower, middle-, and higher-income groups based on whether their income level was in the bottom 25% (family income-to-poverty ratio <1), middle 50% (family income-to-poverty ratio 1–5), or top 25% (family income-to-poverty ratio >5) of the US population. Further analyses were conducted based on education level, with lower educational status characterized as not having a college education and higher educational status characterized as having a college education.¹

Among the overall cohort of 59,204 participants, investigators identified 11,980 participants with chronic liver disease. Compared to those without chronic liver disease, the chronic liver disease group was older (49.59 vs 45.21 years of age), more likely male (57.06% vs 46.01%), a racial and ethnic minority (non-Hispanic black: 12.26% vs 11.86%; Hispanic: 17.57% vs 14.02%, non-Hispanic Asian: 3.67% vs 2.19%), and had lower educational and income levels (all P <.001).¹

Stratification by income revealed participants with chronic liver disease and lower income were older (49.09 vs 50.96 years of age), more likely male (55.17% vs 64.75%), more likely non-Hispanic black (13.61% vs 5.69%) or Hispanic (10.59% vs 5.33%), and had lower educational levels (27.14% vs 6.19% without high school diploma) (all P <.001). Additionally, investigators noted the cumulative 10-year mortality incidence was greater among participants with chronic liver disease and lower income than those with higher income (15.26% vs 8.00%; P <.001), consistent in viral hepatitis (21.92% vs 11.67%; P = .001) and NAFLD (20.22% vs 11.17%; P <.001) subgroups, but not in alcohol-associated liver disease (6.91% vs 5.97%; P = .71).¹

After adjusting for age, sex, race, and birthplace, investigators pointed out lower-income participants with chronic liver disease were 2.01 (hazard ratio [HR], 2.01; 95% CI, 1.79–2.26) times more likely to die overall, consistent in viral hepatitis (HR, 2.05; 95% CI, 1.31–3.24) and NAFLD subgroups (HR, 2.32; 95% CI, 1.69–3.18) but not alcohol-associated liver disease (HR, 1.17; 95% CI, 0.55–2.51). Multivariable Cox regression analyses by education level revealed participants with chronic liver disease without a college education were about 1.5 times more likely to die than those with a college education (HR, 1.52; 95% CI, 1.41–1.64), again consistent in viral hepatitis (HR, 1.38; 95% CI, 1.05–1.81) and NAFLD (HR, 1.38; 95% CI, 1.13–1.67) subgroups.¹

Investigators outlined multiple limitations to these findings, including their reliance on self-reported alcohol consumption for alcohol-associated liver disease and the potential for undersampling of certain populations within NHANES.¹

“Given these findings, interventions must not only be culturally appropriate but also require attention to the potential lack of health literacy and social support and be sex-specific,” investigators concluded.¹

References

1. ^{Nguyen BT, Nguyen VH, Le M, Henry L, Cheung R, Nguyen MH. Impact of Income-to-Poverty Ratio on Long-Term Mortality of Persons with Chronic Liver Disease in the USA, 1999-2018. Dig Dis. Published online June 17, 2024. doi:10.1159/000539858}
2. ^{Sharma A, Nagalli S. Chronic Liver Disease. StatPearls. July 3, 2023. Accessed July 18, 2024. https://www.ncbi.nlm.nih.gov/books/NBK554597/}
3. ^{US Centers for Disease Control and Prevention. Chronic Liver Disease and Cirrhosis. National Center for Health Statistics. November 6, 2023. Accessed July 18, 2024. https://www.cdc.gov/nchs/fastats/liver-disease.htm}