Excess mortality from COVID-19: weekly excess death rates by age and sex for Sweden and its most affected region

Abstract

Background: Sweden has one of the highest numbers of COVID-19 deaths per inhabitant globally. However, absolute death counts can be misleading. Estimating age- and sex-specific mortality rates is necessary in order to account for the underlying population structure. Furthermore, given the difficulty of assigning causes of death, excess all-cause mortality should be estimated to assess the overall burden of the pandemic.

Methods: By estimating weekly age- and sex-specific death rates during 2020 and during the preceding 5 years, our aim is to get more accurate estimates of the excess mortality attributed to COVID-19 in Sweden, and in the most affected region Stockholm.

Results: Eight weeks after Sweden's first confirmed case, the death rates at all ages above 60 were higher than for previous years. Persons above age 80 were disproportionally more affected, and men suffered greater excess mortality than women in ages up to 75 years. At older ages, the excess mortality was similar for men and women, with up to 1.5 times higher death rates for Sweden and up to 3 times higher for Stockholm. Life expectancy at age 50 declined by <1 year for Sweden and 1.5 years for Stockholm compared to 2019.

Conclusions: The excess mortality has been high in older ages during the pandemic, but it remains to be answered if this is because of age itself being a prognostic factor or a proxy for comorbidity. Only monitoring deaths at a national level may hide the effect of the pandemic on the regional level.

Figure 1

Age- and sex-specific weekly death rates in 2020 compared to the 95% confidence interval of average death rates for the corresponding weeks in 2015–19, men, Sweden Notes: The shaded parts are showing the 95% confidence intervals of average age-specific death rates for the period 2015–19. The interval has been calculated based on bootstrapping procedure.

Figure 2

Age- and sex-specific weekly death rates in 2020 compared to the 95% confidence interval of average death rates for the corresponding weeks in 2015–19, women, Sweden Notes: The shaded parts are showing the 95% confidence intervals of average age-specific death rates for the period 2015–19. The interval has been calculated based on bootstrapping procedure.

Figure 3

Age- and sex-specific rate ratios comparing mortality in 2020 to the corresponding weeks in 2015–19, men and women, Sweden Notes: The median of the average age-specific death rates for the period 2015–19 serves as reference. The median has been calculated based on a bootstrapping procedure.

Figure 4

Remaining life expectancy at age 50, 65 and 80 years for the years 2015–20 based on the age-specific death rates measured over the calendar weeks 1–33, men and women, Stockholm county and Sweden