Based on our estimate of population attributable risk, 0.21 million cases (4.04%) of AD might be preventable by treating RAwith a TNF blocking agent, 0.08 million cases (1.51%) of AD might be preventable by treating Crohn’s disease with a TNF blocking agent, and 0.026 million cases (0.50%) of AD might be preventable by treating psoriasis with a TNF blocker or nearly 6% of cases of AD might be prevented by treatment with a TNF blocker. Here, TNF is linked to Crohn disease.