Association of household income with life expectancy and cause-specific mortality in Norway, 2005–2015

Importance

Examining causes of death and making comparisons across countries may increase understanding of the income-related differences in life expectancy.

Objectives

To describe income-related differences in life expectancy and causes of death in Norway and to compare those differences with US estimates.

Design and Setting

A registry-based study including all Norwegian residents aged at least 40 years from 2005 to 2015.

Exposures

Household income adjusted for household size.

Main Outcomes and Measures

Life expectancy at 40 years of age and cause-specific mortality.

Results

In total, 3,041,828 persons contributed 25,805,277 person-years and 441,768 deaths during the study period (mean [SD] age, 59.3 years [13.6]; mean [SD] number of household members per person, 2.5 [1.3]). Life expectancy was highest for women with income in the top 1% (86.4 years [95% CI, 85.7–87.1]) which was 8.4 years (95% CI, 7.2–9.6) longer than women with income in the lowest 1%. Men with the lowest 1% income had the lowest life expectancy (70.6 years [95% CI, 69.6–71.6]), which was 13.8 years (95% CI, 12.3–15.2) less than men with the top 1% income. From 2005 to 2015, the differences in life expectancy by income increased, largely attributable to deaths from cardiovascular disease, cancers, chronic obstructive pulmonary disease, and dementia in older age groups and substance use deaths and suicides in younger age groups. Over the same period, life expectancy for women in the highest income quartile increased 3.2 years (95% CI, 2.7–3.7), while life expectancy for women in the lowest income quartile decreased 0.4 years (95% CI, −1.0 to 0.2). For men, life expectancy increased 3.1 years (95% CI, 2.5–3.7) in the highest income quartile and 0.9 years (95% CI, 0.2–1.6) in the lowest income quartile. Differences in life expectancy by income levels in Norway were similar to differences observed in the United States, except that life expectancy was higher in Norway in the lower to middle part of the income distribution in both men and women.

Conclusions and Relevance

In Norway, there were substantial and increasing gaps in life expectancy by income level from 2005 to 2015. The largest differences in life expectancy between Norway and United States were for individuals in the lower to middle part of the income distribution.