Allergic comorbidities in fibromyalgia.

Background: The relationship between fibromyalgia (FM) and allergic diseases remains poorly understood, despite emerging evidence that suggests a possible association. Objective: This study aimed to evaluate the prevalence of allergic comorbidities in patients with FM compared with a matched control group. Methods: We conducted a retrospective, population-based case-control study within Leumit Health Services, which caters to ∼750,000 members. Patients meeting the evolving criteria of the American College of Rheumatology from January 2002 to December 2023 were included. Control subjects were selected from the same population base but did not have a diagnosis of FM, were matched 5:1 on sex, age, and year of first membership. All diagnoses were identified by using International Classification of Diseases, Ninth Revision (ICD-9) codes up to March 2024. Results: The analysis included 15,869 patients diagnosed with FM and 79,345 matched controls. There was a predominant female representation (82.1%) in both groups. The prevalence of bronchial asthma was higher in patients with FM compared with the controls, with an odds ratio (OR) of 1.91. The patients with FM also exhibited higher rates of both nonseasonal and seasonal allergic rhinitis, with ORs of 1.60 and 1.30, respectively, and chronic rhinosinusitis without nasal polyps demonstrated an OR of 2.46. Acute allergic conjunctivitis had an OR of 2.05. Skin-related allergies such as contact dermatitis and atopic dermatitis showed ORs of 1.48 and 1.41, respectively. Furthermore, the patients with FM displayed elevated rates of various forms of urticaria and chronic pruritus, alongside higher incidences of food allergies and specific drug allergies. Anaphylactic reactions to food were notably more common in patients with FM, who presented an OR of 2.50. Conclusion: FM is associated with a higher prevalence of allergic diseases compared with the controls. Analysis of these findings suggests the need for allergological assessments in FM management.