Body mass index and fitness in late adolescence and risk of cardiovascular disease, respiratory disease, and overall death after COVID-19.

Objective: Since obesity and poor fitness appear to be unfavorable for both cardiovascular health and coping with viral infections such as COVID-19, they are of specific interest in light of the increased risk of cardiovascular and respiratory events now seen after infection with SARS-CoV-2. Therefore, the aim of the present study was to investigate how body mass index (BMI) and cardiorespiratory fitness (CRF) in late adolescence are associated with the risk of cardiovascular disease (CVD), respiratory disease, and mortality after COVID-19. Methods: In this study, 1.5 million 18-year-old Swedish men with BMI and CRF measured during enlistment for military service 1968-2005 were included. Hospitalized and non-hospitalized COVID-19 cases were identified through the Patient Register or positive polymerase chain reaction tests, and age-matched with non-infected controls. CVD, respiratory disease, and mortality after COVID-19 were divided into <60days, 60-180days, >180days post-infection. Cox regression models were used. Results: Hospitalized COVID-19 cases (n = 9839), compared to controls, had >10-fold, 50 to 70-fold, and >70-fold hazards of CVD, respiratory disease, and mortality over the initial 60 days post-infection with little variation across BMI or CRF categories. The elevated risks persisted at declining levels >180 days. For non-hospitalized COVID-19 cases (n = 181,822), there was a 4- to 7-fold increased acute mortality risk, and high CRF was associated with lower risk of post-infectious respiratory disease. Conclusions: The high hazards of adverse outcomes during the first two months after COVID-19 hospitalization, and across BMI and CRF categories, declined rapidly but were still elevated after six months. Adolescent CRF was associated with respiratory disease after COVID-19 without hospitalization, which gives further support to the health benefits of physical activity.

Associations between BMI in youth and site-specific cancer in men-A cohort study with register linkage.

OBJECTIVE: This study examined BMI in young men and incident site-specific cancer to estimate population attributable fractions due to BMI based on projected obesity prevalence. METHODS: A population-based cohort study with measured height and weight at age 18. Cox regression models assessed linear associations for BMI and included age, year, and site of conscription as well as parental level of education as covariates. RESULTS: Primary analyses were performed in 1,489,115 men, of whom 78,217 subsequently developed cancer during a mean follow-up of 31 years. BMI was linearly associated with risk of developing all 18 site-specific cancers assessed (malignant melanoma; leukemia; myeloma; Hodgkin lymphoma; non-Hodgkin lymphoma; and cancer in the lungs, head and neck, central nervous system, thyroid, esophagus, stomach, pancreas, liver and gallbladder, colon, rectum, kidney, and bladder), in some instances evident at BMI levels usually defined as normal (20-25 kg/m2 ). Higher BMI was associated with lower risk of prostate cancer. The highest hazard ratios and population attributable fractions were seen for some gastrointestinal cancers. CONCLUSIONS: This study reports linear associations between BMI at age 18 and subsequent site-specific cancers, calling for rapid action to stem the obesity epidemic and to prepare the health care system for steep increases in cancer cases.

Children in the household and risk of severe COVID-19 during the first three waves of the pandemic: a prospective registry-based cohort study of 1.5 million Swedish men.

OBJECTIVE: To investigate whether Swedish men living with children had elevated risk for severe COVID-19 or infection with SARS-CoV-2 during the first three waves of the pandemic. DESIGN: Prospective registry-based cohort study. PARTICIPANTS: 1 557 061 Swedish men undergoing military conscription between 1968 and 2005 at a mean age of 18.3 (SD 0.73) years. MAIN OUTCOME MEASURES: Infection with SARS-CoV-2 and hospitalisation due to COVID-19 from March 2020 to September 2021. RESULTS: There was a protective association between preschool children at home and hospitalisation due to COVID-19 during the first and third waves compared with only older or no children at all, with ORs (95% CIs) 0.63 (0.46 to 0.88) and 0.75 (0.68 to 0.94) respectively. No association was observed for living with children 6-12 years old, but for 13-17 years old, the risk increased. Age in 2020 did not explain these associations. Further adjustment for socioeconomic and health factors did not attenuate the results. Exposure to preschool children also had a protective association with testing positive with SARS-CoV-2, with or without hospitalisation, OR=0.91 (95% CI 0.89 to 0.93), while living with children of other ages was associated with increased odds of infection. CONCLUSIONS: Cohabiting with preschool children was associated with reduced risk for severe COVID-19. Living with school-age children between 6 and 12 years had no association with severe COVID-19, but sharing the household with teenagers and young adults was associated with elevated risk. Our results are of special interest since preschools and compulsory schools (age 6-15 years) in Sweden did not close in 2020.

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: This study included 1,551,670 Swedish men, born between 1950 and 1987, with BMI registered at age 18 years. 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 included the following: 1) hospitalization; 2) intensive care unit admission; and 3) death. RESULTS: The study found 4,315 cases (mean age = 56.4 years [SD 8.8]) of patients hospitalized because of COVID-19, of which 729 were admitted to an intensive care unit, and altogether there were 224 deaths. The risk for hospital admission increased with higher values of BMI at age 18 years, despite adjustment for comorbidities, from an odds ratio (OR) of 1.19 (95% CI: 1.08-1.31) at BMI = 22.5 to 25 to an OR of 1.68 (95% CI: 1.39-2.02) at BMI ≥ 30, compared with BMI = 18.5 to 20. ORs for intensive care unit admission were 1.44 (95% CI: 1.13-1.84) at BMI = 22.5 to 25 and 2.61 (95% CI: 1.73-3.93) at BMI ≥ 30. CONCLUSIONS: 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.

Fitness, strength and severity of COVID-19: a prospective register study of 1 559 187 Swedish conscripts.

OBJECTIVE: To investigate the possible connection between cardiorespiratory fitness (CRF) and muscle strength in early adulthood and severity of COVID-19 later in life. DESIGN: Prospective registry-based cohort study. PARTICIPANTS: 1 559 187 Swedish men, undergoing military conscription between 1968 and 2005 at a mean age of 18.3 (SD 0.73) years. MAIN OUTCOME MEASURES: Hospitalisation, intensive care or death due to COVID-19 from March to September 2020, in relation to CRF and muscle strength. RESULTS: High CRF in late adolescence and early adulthood had a protective association with severe COVID-19 later in life with OR (95% CI) 0.76 (0.67 to 0.85) for hospitalisation (n=2 006), 0.61 (0.48 to 0.78) for intensive care (n=445) and 0.56 (0.37 to 0.85) for mortality (n=149), compared with the lowest category of CRF. The association remains unchanged when controlled for body mass index (BMI), blood pressure, chronic diseases and parental education level at baseline, and incident cardiovascular disease before 2020. Moreover, lower muscle strength in late adolescence showed a linear association with a higher risk of all three outcomes when controlled for BMI and height. CONCLUSIONS: Physical fitness at a young age is associated with severity of COVID-19 many years later. This underscores the necessity to increase the general physical fitness of the population to offer protection against future viral pandemics.