Premature cardiovascular disease mortality with overweight and obesity as a risk factor: estimating excess mortality in the United States during the COVID-19 pandemic

Abstract

Background: The United States has experienced high levels of excess mortality during the COVID-19 pandemic and also has high prevalence of overweight and obesity, which increases the risk of severe infection and death from the virus. This study uses multiple cause of death data to estimate excess premature cardiovascular disease mortality in the USA in 2020 for which overweight and obesity was a risk factor.

Methods: The contribution of overweight and obesity to premature (35-74 years) cardiovascular disease mortality was measured as cardiovascular disease reported on the death certificate with one or more of diabetes, chronic kidney disease, obesity, lipidemias or hypertensive heart disease (DKOLH-CVD). Excess mortality was calculated as the difference between actual and expected age-standardised death rates. Expected deaths were estimated using negative binomial regressions of monthly deaths during 2010-19.

Results: Excess DKOLH-CVD mortality in March-December 2020 was 29% (95% uncertainty interval 28-31%) for males and 30% (28-32%) for females, much higher than for all causes (males 19% (18-21%), females 16% (14-17%)). Excess mortality was higher where two or more DKOLH conditions (males 40% (37-43%), females 41% (37-44%)) or obesity (males 42% (38-45%), females 47% (43-51%)) were reported. One-half of excess DKOLH-CVD mortality was reported as due to COVID-19, lower than the four-fifths of excess all-cause deaths. For home deaths, just over 10% of excess mortality for each cause classification was reported as due to COVID-19.

Conclusions: Excess premature cardiovascular disease mortality in the USA for which overweight and obesity was a risk factor was considerably higher than for all causes, exacerbating adverse pre-pandemic trends. The contribution of COVID-19 to excess mortality appears significantly under-reported for home deaths.

Fig. 1. Excess mortality (%, based on age-standardised death rate 35–74 years), and contribution of COVID-19 to excess mortality, by sex and cause of death, USA, March–December 2020.

The COVID-19 contribution to excess mortality (blue shaded) was calculated as: (COVID-19 death rate/excess death rate) * excess mortality %. The difference between the blue shaded part and the excess mortality % is the non-COVID contribution to excess mortality (red shaded). The COVID-19 death rate can exceed the excess death rate if there were less deaths than expected from non-COVID causes. In this instance, non-COVID makes a net negative contribution to excess mortality and so is shown as a negative contribution.

Fig. 2. Excess mortality (%, based on age-specific death rates within 35–74 years), and contribution of COVID-19 to excess mortality, by sex, cause of death and age group, USA, March-December 2020.

Age refers to start of five-year age group. Uncertainty intervals shown in Table S1. See Fig. 1 for an explanation of negative non-COVID values.

Fig. 3. Excess mortality (%, based on age-standardised death rate 35–74 years), and contribution of COVID-19 to excess mortality, by sex, place of death (home and hospital) and cause of death, USA, March–December 2020.

See Fig. 1 for an explanation of negative non-COVID values. See Table S3 for uncertainty intervals.