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Body mass index and risk of infections: a Mendelian randomization study of 101,447 individuals.

Authors :
Winter-Jensen M
Afzal S
Jess T
Nordestgaard BG
Allin KH
Source :
European journal of epidemiology [Eur J Epidemiol] 2020 Apr; Vol. 35 (4), pp. 347-354. Date of Electronic Publication: 2020 Apr 19.
Publication Year :
2020

Abstract

Body mass index (BMI) has been related to risk of infections. The aim of this study was to assess the shape of the association between BMI and risk of infections and to evaluate whether such associations represent causality. We included 101,447 individuals from The Copenhagen General Population Study who had BMI measured. Outcome was hospital contacts related to infections. The shape of the association between BMI and risk of infections was examined using restricted cubic spline Cox regression. To evaluate causality, we used Mendelian randomization, an epidemiological method that counteracts confounding and reverse causality by using genetic variation as instrumental variables. We created a genetic risk score based on five genetic variants causing lifelong higher BMI and used this score in instrumental variable analysis. During median follow-up of 8.8 years, 10,263 hospital contacts related to infections were recorded. We found a U-shaped association between BMI and risk of any infection and pneumonia, and a linear association between BMI and risk of skin infection, urinary tract infection, and sepsis. In instrumental variable analyses, higher BMI was associated with increased risk of skin infection: odds ratio 1.12 (95% CI 1.03-1.22) for a genetically induced 1 unit increase in BMI. Observationally, low as well as high BMI was associated with increased risk of any infection and pneumonia, whereas only high BMI was associated with increased risk of skin infection, urinary tract infection, and sepsis. High BMI was causally associated with increased risk of skin infection.

Details

Language :
English
ISSN :
1573-7284
Volume :
35
Issue :
4
Database :
MEDLINE
Journal :
European journal of epidemiology
Publication Type :
Academic Journal
Accession number :
32307655
Full Text :
https://doi.org/10.1007/s10654-020-00630-7