Sex differences in COVID-19 mortality in the Netherlands

Introduction Since the first reports of COVID-19 cases, sex-discrepancies have been reported in COVID-19 mortality. We provide a detailed description of these sex differences in relation to age and comorbidities among notified cases as well as in relation to age and sex-specific mortality in the general Dutch population. Methods Data on COVID-19 cases and mortality until May 31st 2020 was extracted from the national surveillance database with exclusion of healthcare workers. Association between sex and case fatality was analyzed with multivariable logistic regression. Subsequently, male–female ratio in standardized mortality ratios and population mortality rates relative to all-cause and infectious disease-specific mortality were computed stratified by age. Results Male–female odds ratio for case fatality was 1.33 [95% CI 1.26–1.41] and among hospitalized cases 1.27 [95% CI 1.16–1.40]. This remained significant after adjustment for age and comorbidities. The male–female ratio of the standardized mortality ratio was 1.70 [95%CI 1.62–1.78]. The population mortality rate for COVID-19 was 35.1 per 100.000, with a male–female rate ratio of 1.25 (95% CI 1.18–1.31) which was higher than in all-cause population mortality and infectious disease mortality. Conclusion Our study confirms male sex is a predisposing factor for severe outcomes of COVID-19, independent of age and comorbidities. In addition to general male–female-differences, COVID-19 specific mechanisms likely contribute to this mortality discrepancy.