BMI in early adulthood is associated with severe COVID-19 later in life : a prospective cohort study of 1.5 million Swedish men

OBJECTIVE: Overweight and obesity have been identified as risk factors for severe COVID-19, however, prospective cohort studies investigating the association between overweight early in life and severity of COVID-19 are lacking. METHODS: We included 1,551,670 Swedish men, born 1950-1987, with body mass index (BMI) registered at age 18. They were followed until January 9, 2021. COVID-19 cases and comorbidities were identified through the National Patient, Intensive Care, and Cause of Death registries. Outcomes were: 1) hospitalization, 2) intensive care unit admission, and 3) death. RESULTS: We found 4,315 cases (mean age 56.4 years, SD 8.8) hospitalized due to COVID-19, of which 729 were admitted to an intensive care unit, and altogether 224 deaths. The risk for hospital admission increased with higher values of BMI (kg/m2 ), despite adjustment for comorbidities, from odds ratio (OR) 1.19 (95% CI 1.08-1.31) at BMI 22.5-25 to 1.68 (1.39-2.02) at BMI ≥30 compared to BMI 18.5-20. ORs for intensive care unit admission were 1.44 (1.13-1.84) at BMI 22.5-25 and 2.61 (1.73-3.93) at BMI ≥30. CONCLUSION: Higher BMI in early adulthood was associated with severe COVID-19 many years later with a risk increase starting already at BMI ≥22.5. This underlines the necessity of preventive actions against overweight in youth to offer protection against coming viral pandemics