Characteristics and predictors of hospitalization and death in the first 11 122 cases with a positive RT-PCR test for SARS-CoV-2 in Denmark: a nationwide cohort

Abstract

Background: Population-level knowledge on individuals at high risk of severe and fatal coronavirus disease 2019 (COVID-19) is urgently needed to inform targeted protection strategies in the general population.

Methods: We examined characteristics and predictors of hospitalization and death in a nationwide cohort of all Danish individuals tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from 27 February 2020 until 19 May 2020.

Results: We identified 11 122 SARS-CoV-2 polymerase chain reaction-positive cases of whom 80% were community-managed and 20% were hospitalized. Thirty-day all-cause mortality was 5.2%. Age was strongly associated with fatal disease {odds ratio [OR] 15 [95% confidence interval (CI): 9-26] for 70-79 years, increasing to OR 90 (95% CI: 50-162) for ≥90 years, when compared with cases aged 50-59 years and adjusted for sex and number of co-morbidities}. Similarly, the number of co-morbidities was associated with fatal disease [OR 5.2 (95% CI: 3.4-8.0), for cases with at least four co-morbidities vs no co-morbidities] and 79% of fatal cases had at least two co-morbidities. Most major chronic diseases were associated with hospitalization, with ORs ranging from 1.3-1.4 (e.g. stroke, ischaemic heart disease) to 2.6-3.4 (e.g. heart failure, hospital-diagnosed kidney disease, organ transplantation) and with mortality with ORs ranging from 1.1-1.3 (e.g. ischaemic heart disease, hypertension) to 2.5-3.2 (e.g. major psychiatric disorder, organ transplantation). In the absence of co-morbidities, mortality was <5% in persons aged ≤80 years.

Conclusions: In this nationwide population-based COVID-19 study, increasing age and multimorbidity were strongly associated with hospitalization and death. In the absence of co-morbidities, the mortality was, however, <5% until the age of 80 years.

Keywords: COVID-19; SARS-CoV-2; death; epidemiology; hospitalization; infectious disease; population-based; predictors.

Figure 1

New SARS-CoV-2 PCR-positive cases and the number of individuals who tested negative for SARS-CoV-2 per day during the stages of the ongoing epidemic. The dotted lines illustrate the shift from containment to mitigation strategy as well as to the reopening of society. Note logarithmic y-axis. Cases diagnosed before 5 March are omitted to ensure anonymity.

Figure 2

(A) Distribution of hospitalization and death according to age group in all SARS-CoV-2 PCR-positive cases. (B) The proportion of hospitalized and fatal SARS-CoV-2 cases per 100 000 individuals relative to the total Danish population within each age group Fatal cases were defined as all PCR-positive cases who died of all causes within 30 days from the index date.

Figure 3.

Heat map illustrating proportion of patients dying (in %) among SARS-CoV-2 PCR-positive cases within different subgroups of age and number of co-morbidities Total number of co-morbidities is assessed as the total number of any of the following conditions: chronic lung disease, hypertension, ischaemic heart disease, heart failure, atrial fibrillation, stroke, diabetes, dementia, cancer, chronic liver disease, hospital-diagnosed kidney disease, alcohol abuse, substance abuse, major psychiatric disorder, organ transplantation, overweight and obesity, and rheumatoid arthritis/connective-tissue disease. Mortality was defined as all-cause mortality within 30 days from the index date. Stated mortality proportions in % in each subgroup are rounded to the nearest number (green <1.50%; yellow 1.50–10.49%; orange 10.50–20.49%; red >20.49%). The value 0% means that <0.5% in the subgroup died or that there were no patients in the subgroup.