Does sex modify the effect of pre-pandemic body mass index on the risk of Long COVID? Evidence from the longitudinal analysis of the Survey of Health, Ageing and Retirement in Europe

BackgroundResearch on Long COVID risk factors is ongoing. High body mass index (BMI) may increase Long COVID risk, yet no evidence has been established regarding sex differences in the relationship between BMI and the risk of Long COVID. Investigating the nature of this relationship was the main objective of this study.MethodsA population-based prospective study involving a sample of respondents aged 50 years and older (n = 4004) from 27 European countries that participated in the 2020 and 2021 Survey of Health, Ageing and Retirement in Europe's (SHARE) Corona Surveys and in Waves 7 and 8 of the main SHARE survey. Logistic regression models were estimated to produce unadjusted and adjusted estimates of the sex differences in the relationship between BMI and Long COVID.ResultsLinear relationship for females, with probability of Long COVID increasing with BMI (68% at BMI = 18, 93% at BMI = 45). Non-linear relationship for males, with probability of Long COVID of 27% at BMI = 18, 68% at BMI = 33, and 40% at BMI = 45. Relationships remained significant after adjusting for known Long COVID risk factors (age and COVID-19 hospitalization), presence of chronic diseases, and respondents' place of residence.ConclusionSex differences appear to play an important role in the relationship between BMI and risk of Long COVID. Overall, females were more likely to have Long COVID, regardless of their BMI. Males at the higher end of the BMI spectrum had a lower risk of Long COVID as opposed to their female counterparts. Sex-specific research is recommended for better understanding of Long COVID risk factors.