Lifestyle change of little help in reducing risk of death, CVD in poor adults

A study of two large nationwide US and UK cohorts reveals that low socioeconomic status (SES) is significantly associated with higher risks of mortality and incident cardiovascular disease (CVD). Lifestyle factors modestly mediate these associations.

“[T]herefore, healthy lifestyle promotion alone might not substantially reduce the socioeconomic inequity in health, and other measures tackling social determinants of health are warranted,” the researchers said.

This population-based cohort study utilized the US National Health and Nutrition Examination Survey (US NHANES; 1988–1994 and 1999–2004) and the UK Biobank and included 44,462 US adults aged ≥20 years and 399,537 UK adults aged 37–73 years.

Latent class analysis derived SES using family income, occupation or employment status, education level, and health insurance (US NHANES only); three levels (low, medium, and high) were defined according to item response probabilities.

Moreover, the researchers generated a healthy lifestyle score using information on never smoking, no heavy alcohol consumption (women ≤1 drink/day; men ≤2 drinks/day; one drink contains 14 g of ethanol in the US and 8 g in the UK), top third of physical activity, and higher dietary quality.

A total of 8,906 deaths was recorded by US NHANES over a mean follow-up of 11.2 years, while the UK Biobank documented 22,309 deaths and 6,903 incident CVD cases over a mean follow-up of 8.8–11.0 years. [BMJ 2021;373:n604]

The age-adjusted mortality risk among adults of low SES was 22.5 (95 percent confidence interval [CI], 21.7–23.3) per 1,000 person-years in US NHANES and 7.4 (95 percent CI, 7.3–7.6) in UK Biobank; the age-adjusted CVD risk was 2.5 (95 percent CI, 2.4–2.6) per 1,000 person-years in UK Biobank. The corresponding risks among adults of high SES were significantly lower at 11.4 (95 percent CI, 10.6–12.1), 3.3 (95 percent CI, 3.1–3.5), and 1.4 (95 percent CI, 1.3–1.5) per 1,000 person-years.

Adults of low vs high SES had higher risks of all-cause mortality (hazard ratio [HR], 2.13, 95 percent CI, 1.90–2.38 in US NHANES; HR, 1.96, 95 percent CI, 1.87–2.06 in UK Biobank), CVD mortality (HR, 2.25, 95 percent CI, 2.00–2.53), and incident CVD (HR, 1.65, 95 percent CI, 1.52–1.79) in UK Biobank; the proportions mediated by lifestyle were 12.3 percent (10.7–13.9), 4.0 percent (3.5–4.4), 3.0 percent (2.5–3.6), and 3.7 percent (3.1–4.5), respectively.

There was no significant association between lifestyle and SES in US NHANES, but interactions between lifestyle and outcomes were stronger among those of low SES in UK Biobank.

Adults with low SES and no or one healthy lifestyle factor had higher risks of all-cause mortality (US NHANES: HR, 3.53, 95 percent CI, 3.01–4.14; UK Biobank: HR, 2.65, 95 percent CI, 2.39–2.94), CVD mortality (HR, 2.65, 95 percent CI, 2.09–3.38), and incident CVD (HR, 2.09, 95 percent CI, 1.78–2.46) in UK Biobank than those with high SES and three or four healthy lifestyle factors.

“The finding argues for government policies to tackle upstream social and environmental determinants of health,” the researchers said. [Lancet 2008;372:1661-1669]

“Nevertheless, individuals with disadvantaged SES and unhealthy lifestyles had the highest risks of mortality and incident CVD, which highlights the importance of lifestyle modification in reducing disease burden for all people, especially those of low SES in the UK,” they added.