Research Paper
Socioeconomic inequalities in the incidence of alcohol-related liver disease: A nationwide Danish study
Summary
Background
There is socio-economic inequality in total alcohol-related harm, but knowledge of inequality in the incidence of specific alcohol-related diseases would be beneficial for prevention. Registry-based studies with nationwide coverage may reveal the full burden of socioeconomic inequality compared to what can be captured in questionnaire-based studies.
The researchers examined the incidence of alcohol-related liver disease (ALD) according to socioeconomic status and age.
Methods
The researchers used national registries to identify patients with an incident diagnosis of ALD and their socioeconomic status in 2009–2018 in Denmark. They computed ALD incidence rates by socioeconomic status (education and employment status) and age-group (30–39, 40–49, 50–59, 60–69 years) and quantified the inequalities as the absolute and relative difference in incidence rates between low and high socioeconomic status.
Findings
- Of 17,473 patients with newly diagnosed ALD, 78% of whom had cirrhosis, 86% had a low or medium-low educational level and only 20% were employed.
- ALD patients were less likely to be employed in the 10 years prior to diagnosis than controls. The incidence rate of ALD correlated inversely with educational level, from 181 to 910 per million person-years from the highest to the lowest educational level.
- By employment status, the incidence rate per million person-years was 211 for employed and 3449 for unemployed. Incidence rates increased gradually with age leading to larger inequalities in absolute numbers for older age-groups.
- Although ALD was rare in the younger age-groups, the relative differences in incidence rates between high and low socioeconomic status were large for these ages.
- The pattern of socioeconomic inequality in ALD incidence was similar for men and women.
Interpretation
This study showed substantial socioeconomic inequalities in ALD incidence for people aged 30–69 years.
Research in context
Evidence before this study
The researchers initially searched MEDLINE in April, 2020, using keywords including “liver”, “cirrhosis”, “alcohol”, “socioeconomic status”, “socioeconomic position”, “deprivation”, and “inequalities”. Previous studies found a socioeconomic gradient in total alcohol-related morbidity and mortality.
A systematic review published in 2015 on the relation between socioeconomic status and alcohol-attributable harms concluded that few studies had investigated the socioeconomic pattern of single alcohol-related diseases and that such knowledge would be beneficial for prevention purposes. For instance, prevention programs of liver disease that develops after chronic heavy alcohol use would be different than prevention programs of alcohol-related accidents resulting from acute alcohol poisoning. Moreover, application of both an absolute and relative measure of inequality in disease is recommended by the World Health Organization.
Added value of this study
This nationwide study, based on a population with access to universal healthcare, social security benefits, and free education, showed substantial inequalities in the incidence of alcohol-related liver disease in ages 30–69 years. This is the first study of socioeconomic inequality in alcohol-related liver disease incidence applying both an absolute and relative measure of inequality.
Application of the absolute measure of inequality showed a huge burden of alcohol-related liver disease incidence for people of low socioeconomic status after the age of 40 years. This follows the increasing incidence of alcohol-related liver disease with age until 60–70 years.
Application of the relative measure of inequality revealed that the inequality was present already in the age-group of 30–39 years. Moreover, the study showed that the difference in employment status between alcohol-related liver disease patients and controls was evident several years before the ALD diagnosis pointing to a window of opportunity for prevention.
Implications of all the available evidence
The huge socioeconomic inequality in alcohol-related disease should make governments and healthcare institutions consider alcohol control policies such as minimum unit pricing which has greater impact among groups of lower socioeconomic status.
On the individual level, research is needed to investigate an effect of liver-specific prevention programs. For example, non-invasive screening for liver disease followed by treatment of the underlying cause may be offered at the social security offices to people who are unemployed or receiving disability pension.