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

Abstract

Objective: To study body mass index (BMI) changes among individuals aged 18-99 years with and without SARS-CoV-2 infection.

Subjects/methods: 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.

Results: 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.

Conclusions: 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.

Figure 1

All estimates are from the marginal structural model with statistical interaction of exposure group, effect modifier (i.e., sex, age, race-ethnicity, hospitalization status) and time. Associations are adjusted for BMI closest to index date during lookback period and any imbalanced covariates. Associations reported above are also available in Supplementary Table 5. Our historical cohort corresponds with the blue lines. Our unexposed cohort corresponds with the green lines. Our exposed cohort corresponds with the red lines. Panel A: Difference relative to Exposed cohort at start of follow-up. Panel B: Difference relative to Exposed cohort per 100 days of follow-up.