ABSTRACT
BACKGROUND: Factors associated with severe COVID-19 and death among young adults are not fully understood, including differences between the sexes. The aim of this study was to identify factors associated with severe COVID-19 requiring intensive care and 90-day mortality among women and men below 50 years of age. METHODS: A register-based study using data from mandatory national registers, where patients with severe COVID-19 admitted to the ICU with need for mechanical ventilation (cases) between March 2020 and June 2021 were matched regarding age, sex, and district of residence with 10 population-based controls. Both the study population and the controls were divided into groups based on age (< 50 years, 50-64, and ≥ 65 years) and sex. Multivariate logistic regression models including socioeconomic factors were used to calculate odds ratios (OR) with 95% confidence intervals (CIs) for associations between severe COVID-19 in the population to compare the magnitude of the risk associations for co-morbidities in the different age categories, and subsequently factors associated with 90-day mortality among patients admitted to ICU. RESULTS: In total, 4921 cases and 49,210 controls (median age 63 years, 71% men) were included. The co-morbidities with the strongest associations with severe COVID-19 for the young population compared to older patients were chronic kidney disease (OR 6.80 [3.61-12.83]), type 2 diabetes (OR 6.31 [4.48-8.88]), hypertension (OR 5.09 [3.79-6.84]), rheumatoid arthritis (OR 4.76 [2.29-9.89]), obesity (OR 3.76 [2.88-4.92]), heart failure (OR 3.06 [1.36-6.89]), and asthma (OR 3.04 [2.22-4.16]). When comparing women vs. men < 50 years of age, stronger associations were seen for women regarding type 2 diabetes (OR 11.25 [6.00-21.08] vs OR 4.97 [3.25-7.60]) and hypertension (OR 8.76 [5.10-15.01] vs OR 4.09 [2.86-5.86]). The factors associated with 90-day mortality in the young were previous venous thromboembolism (OR 5.50 [2.13-14.22]), chronic kidney disease (OR 4.40 [1.64-11.78]) and type 2 diabetes (OR 2.71 [1.39-5.29]). These associations with 90-day mortality were foremost driven by the female population. CONCLUSION: Chronic kidney failure, type 2 diabetes, hypertension, rheumatoid arthritis, obesity, heart failure, and asthma were the strongest risk factors associated with severe COVID-19 requiring ICU-care in individuals < 50 years compared to the older population. However, after ICU admission, previous thromboembolism, chronic kidney failure, and type 2 diabetes were associated with increased 90-day mortality. The risk associations for co-morbidities were generally stronger among younger individuals compared to older and in women compared to men.
ABSTRACT
To determine whether immigrant background and socioeconomic status were associated with increased risk to develop severe Coronavirus disease 2019 (COVID-19) requiring mechanical ventilation at the intensive care unit and to study their effects on 90-day mortality. Nationwide case-control study with personal-level data from the Swedish Intensive Care register linked with socioeconomic data from Statistics Sweden and comorbidity data from the national patient register. For each case of COVID-19 treated with mechanical ventilation at the intensive care unit (outcome), 10 population controls were matched for age, sex and area of residence. Logistic and Cox regression were used to study the association between the exposure (immigrant background, income and educational level) and 90-day mortality. In total, 4 921 cases and 49 210 controls were matched. In the adjusted model, the risk of severe COVID-19 was highest in individuals born in Asia (Odds ratio [OR] = 2.44, 95% confidence interval [CI] = 2.20-2.69), South America (OR = 2.34, 95% CI = 1.82-2.98) and Africa (OR = 2.11, 95% CI = 1.76-2.50). Post-secondary education was associated with a lower risk of severe COVID-19 (OR = 0.75, CI = 0.69-0.82) as was the highest (vs. lowest) income quintile (OR = 0.87, CI = 0.77-0.97). In the fully adjusted Cox-regression analysis birth region of Africa (OR 1.38, CI = 1.03-1.86) and high income (OR 0.75, CI 0.63-0.89) were associated with 90-day mortality. Immigrant background, educational level and income were independently associated with acquiring severe COVID-19 with need for mechanical ventilation.