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). Body mass index (kg/m²) was retrieved from objective measures of height and weight in electronic health records. We used target trial approaches to estimate BMI at baseline 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 44,436 (Exposed cohort), 164,118 (Unexposed cohort), and 41,189 (Historical cohort). Cumulatively, 62% were women, 21.5% Non-Hispanic Black, 21.4% Hispanic and 5.6% Non-Hispanic Other. Patients had an average age of 51.9 years (SD: 18.9). At baseline, relative to the Exposed cohort (mean BMI: 29.3 kg/m² [95%CI: 29.0, 29.7]), the Unexposed (-0.07 kg/m² [95%CI; -0.12, -0.01]) and Historical controls (-0.27 kg/m² [95%CI; -0.34, -0.20]) had lower BMI. Relative to no change in the Exposed over 100 days (0.00 kg/m² [95%CI; -0.03,0.03]), the BMI of those Unexposed decreased (-0.04 kg/m² [95%CI; -0.06, -0.01]) while the Historical cohort's BMI increased (+0.03 kg/m² [95%CI;0.00,0.06]). BMI changes were consistent between Exposed and Unexposed cohorts for most population groups, except at start of follow-up period among Males and those 65 years or older, and in changes over 100 days among Males and Hispanics.

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.. Difference from Exposed cohort in body mass index at start of post-acute period and change per 100 days of follow-up for Unexposed and Historical cohorts.

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. 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.