Causal association between body mass index and risk of rheumatoid arthritis: A Mendelian randomization study

Sang Cheol Bae, Young Ho Lee

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    23 Citations (Scopus)


    Objective: This study aimed to examine whether body mass index (BMI) is causally associated with rheumatoid arthritis (RA). Method: A two-sample Mendelian randomization (MR) analysis using the inverse-variance weighted (IVW), weighted median and MR-Egger regression methods was performed. We used the publicly available summary statistics data sets of genome-wide association studies (GWAS) meta-analyses for BMI in individuals of European descent (n = 322 154; GIANT consortium) as the exposure and a GWAS for noncancer illness code self-reported: RA from the individuals included in the UK Biobank (total n = 337 159; case = 7480, control = 329 679) as the outcome. Results: We selected 68 single nucleotide polymorphisms at genome-wide significance from GWASs on BMI as the instrumental variables. The IVW method showed evidence to support a causal association between BMI and RA (beta = 0.003, SE = 0.001, P = 0.033). MR-Egger regression revealed that directional pleiotropy was unlikely to be biasing the result (intercept = −3.54E-05; P = 0.736), but it showed no causal association between BMI and RA (beta = 0.004, SE = 0.004, P = 0.302). However, the weighted median approach yielded evidence of a causal association between BMI and RA (beta = 0.006, SE = 0.002, P = 0.004). Cochran's Q test and the funnel plot indicated no evidence of heterogeneity and asymmetry, indicating no directional pleiotropy. Conclusion: The results of MR analysis support that BMI may be causally associated with an increased risk of RA.

    Original languageEnglish
    Article numbere13076
    JournalEuropean Journal of Clinical Investigation
    Issue number4
    Publication statusPublished - 2019 Apr

    Bibliographical note

    Funding Information:
    This study was supported in part by the Bio & Medical Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science & ICT (NRF‐2017M3A9B4050335), Republic of Korea.

    Publisher Copyright:
    © 2019 Stichting European Society for Clinical Investigation Journal Foundation


    • BMI
    • mendelian randomization
    • rheumatoid arthritis

    ASJC Scopus subject areas

    • Biochemistry
    • Clinical Biochemistry


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