Comparison of Health Outcomes Among High- and Low-Income Adults Aged 55 to 64 Years in the US vs England

Abstract

Importance: Socioeconomic differences in life expectancy, health, and disability have been found in European countries as well as in the US. Identifying the extent and pattern of health disparities, both within and across the US and England, may be important for informing public health and public policy aimed at reducing these disparities.

Objective: To compare the health of US adults aged 55 to 64 years with the health of their peers in England across the high and low ranges of income in each country.

Design, setting, and participants: Using data from the Health and Retirement Study (HRS) and the English Longitudinal Study of Ageing (ELSA) for 2008-2016, a pooled cross-sectional analysis of comparably measured health outcomes, with adjustment for demographic characteristics and socioeconomic status, was conducted. The analysis sample included community-dwelling adults aged 55 to 64 years from the HRS and ELSA, resulting in 46 887 person-years of observations. Data analysis was conducted from September 17, 2019, to May 12, 2020.

Exposures: Residence in the US or England and yearly income.

Main outcomes and measures: Sixteen health outcomes were compared, including 5 self-assessed outcomes, 3 directly measured outcomes, and 8 self-reported physician-diagnosed health conditions.

Results: This cross-sectional study included 12 879 individuals and 31 928 person-years from HRS (mean [SD] age, 59.2 [2.8] years; 51.9% women) and 5693 individuals and 14 959 person-years from ELSA (mean [SD] age, 59.3 [2.9] years; 51.0% women). After adjusting for individual-level demographic characteristics and socioeconomic status, a substantial health gap between lower-income and higher-income adults was found in both countries, but the health gap between the bottom 20% and the top 20% of the income distribution was significantly greater in the US than England on 13 of 16 measures. The adjusted US-England difference in the prevalence gap between the bottom 20% and the top 20% ranged from 3.6 percentage points (95% CI, 2.0-5.2 percentage points) in stroke to 9.7 percentage points (95% CI, 5.4-13.9 percentage points) for functional limitation. Among individuals in the lowest income group in each country, those in the US group vs the England group had significantly worse outcomes on many health measures (10 of 16 outcomes in the bottom income decile); the significant differences in adjusted prevalence of health problems in the US vs England for the bottom income decile ranged from 7.6% (95% CI, 6.0%-9.3%) vs 3.8% (95% CI, 2.6%-4.9%) for stroke to 75.7% (95% CI, 72.7%-78.8%) vs 59.5% (95% CI, 56.3%-62.7%) for functional limitation. Among individuals in the highest income group, those in the US group vs England group had worse outcomes on fewer health measures (4 of 16 outcomes in the top income decile); the significant differences in adjusted prevalence of health problems in the US vs England for the top income decile ranged from 36.9% (95% CI, 33.4%-40.4%) vs 30.0% (95% CI, 27.2%-32.7%) for hypertension to 35.4% (95% CI, 32.0%-38.7%) vs 22.5% (95% CI, 19.9%-25.1%) for arthritis.

Conclusions and relevance: For most health outcomes examined in this cross-sectional study, the health gap between adults with low vs high income appeared to be larger in the US than in England, and the health disadvantages in the US compared with England are apparently more pronounced among individuals with low income. Public policy and public health interventions aimed at improving the health of adults with lower income should be a priority in the US.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Clarke reported receiving grants from the National Institutes of Health (NIH) during the conduct of the study. Dr Jivraj reported receiving grants from the National Institute of Aging (NIA) during the conduct of the study. Dr Langa reported receiving grants from the NIH/NIA during the conduct of the study. No other disclosures were reported.

Figures

Figure 1.. Adjusted Risk Ratios (ARRs) for US-England Health Differences at Ages 55 to 64 Years for 2008-2016

Adjustment factors included survey year, age, sex, race, foreign-born status (outside the US for HRS; outside the UK for ELSA), household size, marital status, educational level in International Standard Classification of Education categories, and household income in decile. Estimates were calculated holding all adjustment factors at their grand mean values (ie, constant across countries). ADL indicates activities of daily living; CES-D8, 8-item Center for Epidemiologic Studies Depression Scale; CRP, C-reactive protein; HbA1c, hemoglobin A1c; and IADL, instrumental ADL.

Figure 2.. Adjusted Prevalence of Self-assessed Health Outcomes at Ages 55 to 64 Years for 2008-2016 by Country-Specific Income Decile

Adjustment factors include age, year, sex, foreign-born status (outside the US for HRS; outside the UK for ELSA), race, household size, and marital status. Estimates were calculated holding all adjustment factors at their grand mean values (ie, constant across countries and income deciles). Error bars show 95% CIs. ADL indicates activities of daily living; ELSA, English Longitudinal Study of Ageing; HRS, Health and Retirement Study; and IADL, instrumental ADL.

Figure 3.. Adjusted Prevalence of Measured Health Outcomes at Ages 55 to 64 Years for 2008-2016 by Country-Specific Income Decile

Adjustment factors included age, year, sex, foreign-born status (outside the US for HRS; outside the UK for ELSA), race, household size, and marital status. Estimates were calculated holding all adjustment factors at their grand mean values (ie, constant across countries and income deciles). Error bars show 95% CIs. CRP indicates C-reactive protein; ELSA, English Longitudinal Study of Ageing; HbA1c, hemoglobin A1c; and HRS, Health and Retirement Study. SI conversion factors: To convert CRP to milligrams per liter, multiply by 10; HbA1c to proportion of total Hb, multiply by 0.01.

Figure 4.. Adjusted Prevalence of Self-reported Physician-Diagnosed Health Conditions at Ages 55 to 64 Years for 2008-2016 by Country-Specific Income Decile

Adjustment factors included age, year, sex, foreign-born status (outside the US for HRS; outside the UK for ELSA), race, household size, and marital status. Estimates were calculated holding all adjustment factors at their grand mean values (ie, constant across countries and income deciles). Error bars show 95% CIs. ELSA indicates English Longitudinal Study of Ageing; HRS, Health and Retirement Study.