Fig. 1From: Asthma and atopic dermatitis as risk factors for rheumatoid arthritis: a bidirectional mendelian randomization studyThe rationale of Mendelian randomization 1 represents the instrumental variables (IVs) that are strongly associated with the exposure; 2 indicates the IVs must influence the outcome only through the exposure; 3 shows the IVs must not associate with con-foundersBack to article page