[Causality between atopic diseases and osteoarthritis:a Mendelian randomization study]

To explore causal relationship between atopic diseases (asthma and atopic dermatitis) and osteoarthritis (OA) by using mendelian randomization(MR).

Asthma and atopic dermatitis as instrumental variables were selected, searched them through IEU database, and selected the latest data with a large number of cases and single nucleotide polymorphism (SNP). Data were collected and processed using R language, inverse varianceweighted (IVW) method was adopted as main MR Evaluation method. Single linear regression was performed to estimate causality based on pooled knee and hip data from genome-wide association studies (GWAS). The forest map was drawn to visualize the results, and gene pleiotropy and sensitivity were analyzed by scatter plot and funnel plot. At the same time, asthma, atopic dermatitis, body mass index (BMI), osteoporosis and OA were selected for multivariate MR Analysis to exclude the effect of horizontal pleiotropy on the results in GWAS data.

Analysis of MR-IVW results showed asthma was positively correlated with causal effect of OA [OR=1.41, 95%CI(1.07, 1.85), P=0.02], multivariate Mendelian randomization (MVMR) adjusted for BMI and osteoporosis and a direct causal effect on OA was observed [OR=1.57, 95%CI(1.03, 2.39), P=0.03)]. MR Results of two samples of atopic dermatitis and OA were [OR=1.01, 95%CI(0.97, 1.04), P=0.76], and MVMR results were [OR=1.02, 95%CI(0.99, 1.05), P=0.25], indicating no clear causal relationship between two samples.

Asthma could increase risk of OA, atopic dermatitis has no obvious relationship with OA, and the relationship between atopic diseases and OA still needs to be discussed.