Age Categories Used Are Too Broad

Numerous studies have examined whether there was excess mortality during the COVID-19 pandemic (1, 2). Comparative evaluations showed that the results depend heavily on the methods used (1, 2). However, it is essential to take age into account (1). In Germany, the number of people aged over 80 rose from 4.8 million to 5.8 million between 2016 and 2020 (3). This means that an increase in the number of deaths would have been expected even without the COVID-19 pandemic, and that the aging of the population must be taken into account in the analysis.

Morfeld et al. recently examined mortality in Germany in 2020 and 2021 using data from the German Federal Statistical Office and estimated the standardized mortality ratios (SMR) to be 1.06 [95% confidence interval: 1.04; 1.08] and 1.09 [1.07; 1.11], respectively (4). Although the data from the German Federal Statistical Office allow a finer categorization (0–30 years old, with 5-year age groups starting from >30 years old), the authors only used very broad age categories (< 65 years, ≥ 65 years) for the age standardization. We were able to show the influence of adequate consideration of age on the basis of our own analyses of data from the Federal Statistical Office: with broad grouping (< 65, ≥ 65 years), the SMR was 1.036 [1.033; 1.039] for men, and 1.013 [1.010; 1.016] for women; in contrast, the corresponding SMRs using a narrower grouping are significantly lower (0.998 [0.996; 1.001] and 0.991 [0.988; 0.994], respectively) (unpublished analysis for broad age categories) (2). The importance of using age standardization is also reflected in the analyses by Levitt et al., who estimate an excess mortality of 2.7% for Germany with age standardization for the years 2020 and 2021, and 6.4% without age standardization (1).