Body mass index changes and their association with SARS-CoV-2 infection: a real-world analysis

To study body mass index (BMI) changes among individuals aged 18–99 years with and without SARS-CoV-2 infection. Using real-world data from the OneFlorida+ Clinical Research Network of the National Patient-Centered Clinical Research Network, we compared changes over time in BMI in an Exposed cohort (positive SARS-CoV-2 test between March 2020–January 2022), to a contemporary Unexposed cohort (negative SARS-CoV-2 tests), and an age/sex-matched Historical control cohort (March 2018–January 2020). BMI (kg/m2) was retrieved from objective measures of height and weight in electronic health records. We used target trial approaches to estimate BMI at start of follow-up and change per 100 days of follow-up for Unexposed and Historical cohorts relative to the Exposed cohort by categories of sex, race & ethnicity, age, and hospitalization status. The study sample consisted of 249,743 participants (19.2% Exposed, 61.5% Unexposed, 19.3% Historical cohort) of whom 62% were women, 21.5% Non-Hispanic Black, 21.4% Hispanic and 5.6% Non-Hispanic other and had an average age of 51.9 years (SD: 18.9). At start of follow-up, relative to the Unexposed cohort (mean BMI: 29.3 kg/m2 [95% CI: 29.1, 29.4]), the Exposed (0.07 kg/m2 [95% CI; 0.01, 0.12]) had higher mean BMI and Historical controls (−0.20 kg/m2 [95% CI; −0.25, −0.15]) had lower mean BMI. Over 100 days, BMI did not change (0 kg/m2 [95% CI: −0.03, 0.03]) for the Exposed cohort, decreased (−0.04 kg/m2 [95% CI; −0.05, −0.02]) for the Unexposed cohort and increased (0.03 kg/m2 [95% CI; 0.01, 0.04]) for the Historical cohort. Observed differences in BMI at start of follow-up and over 100 days were consistent between Unexposed and Exposed cohorts for most subgroups, except at start of follow-up period among Males and those 65 years or older who had lower BMI among Exposed. In a diverse real-world cohort of adults, mean BMI of those with and without SARS-CoV2 infection varied in their trajectories. The mechanisms and implications of weight retention following SARS-CoV-2 infection remain unclear.