Achalasia is Strongly Associated With Eosinophilic Esophagitis and Other Allergic Disorders

Background & Aims: Achalasia has been assumed to be an autoimmune disease targeting esophageal myenteric neurons. Recently, we proposed an alternative hypothesis that achalasia sometimes might be allergy-driven, caused by a form of eosinophilic esophagitis (EoE) in which activated eosinophils and/or mast cells infiltrating esophageal muscle release products that disrupt motility and damage myenteric neurons. To seek epidemiologic support for this hypothesis, we identified patients with achalasia in the Utah Population Database, and explored their frequency of having EoE and other allergic disorders. Methods: We used International Classification of Diseases codes to identify patients with achalasia and allergic disorders including EoE, asthma, atopic dermatitis, contact dermatitis, allergic rhinitis, allergic conjunctivitis, hives/urticaria, and anaphylaxis. We calculated relative risk (RR) for each allergic disorder by comparing the number observed in patients with achalasia with the expected number in individuals matched for birthyear and sex, and we performed subanalyses for patients age ≤40 versus age >40 years. Results: Among 844 patients with achalasia identified (55% female; median age at diagnosis, 58 years), 402 (47.6%) had ≥1 allergic disorder. Fifty-five patients with achalasia (6.5%) had EoE (1.67 EoE cases expected), for a RR of 32.9 (95% confidence interval, 24.8–42.8; P <.001). In 208 patients with achalasia age ≤40 years, the RR for EoE was 69.6 (95% confidence interval, 46.6–100.0; P <.001). RR also was increased significantly for all other allergic disorders evaluated (all greater than 3-fold higher than population rates). Conclusions: Achalasia is strongly associated with EoE and other allergic disorders. These data support the hypothesis that achalasia sometimes might have an allergic etiology.