Factors associated with hospitalization,invasive mechanical ventilation treatment and death among all confirmed COVID-19 cases in Norway: Prospective cohort study

Aims: For everyone with a positive test for SARS-CoV-2 in Norway, we studied whether age, sex, comorbidity, continent of birth and nursing home residency were risk factors for hospitalization, invasive mechanical ventilation treatment and death. Methods: Data for everyone who had tested positive for SARS-CoV-2 in Norway by end of June 2020 (N = 8569) were linked at the individual level to hospitalization, receipt of invasive mechanical ventilation treatment and death measured to end of July 2020. Underlying comorbidity was proxied by hospital-based in- or outpatient treatment during the two months before the SARS-CoV-2 test. Multivariable generalized linear models were used to assess risk ratios (RRs). Results: Risk of hospitalization was particularly high for elderly (for those aged 90 and above: RR 9.5; 95% confidence interval (CI) 7.1–12.7; comparison group aged below 50), Norwegian residents born in Asia, Africa or Latin-America (RR 2.1; 95% CI 1.9–2.4; comparison group born in Norway), patients with underlying comorbidity (RR 1.6; 95% CI 1.4–1.8) and men (RR 1.3; 95% CI 1.2–1.5). Men and residents born in Africa, Asia and Latin-America were also at higher risk of receiving ventilation treatment and dying, but the mortality risk was especially high for the elderly (for those aged 90 and above: RR 607.9; 95% CI 145.5–2540.1; comparison group aged below 50) and residents in nursing homes (RR 4.2; 95% CI 3.1–5.7). Conclusions: High age was the most important predictor of severe disease and death if infected with SARS-CoV-2, and nursing home residents were at particularly high risk of death.