Seasonal, food allergies linked to higher alopecia areata risk
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Key takeaways:
- Patients with both a seasonal and a food allergy were most at risk for alopecia areata compared with other groups.
- Higher IgE levels were also positively associated with the presence of alopecia areata.
The risk of developing alopecia areata increases when both seasonal and food allergies are present, according to a study published in The European Journal of Allergy and Clinical Immunology.
“This study was prompted by emerging evidence that type 2 inflammation plays a role in alopecia areata,” Benjamin Ungar, MD, director of the Alopecia Center of Excellence and director of the Rosacea & Seborrheic Dermatitis Clinic at Mount Sinai, told Healio.
“There are different aspects to this connection, but part of it is that some studies have suggested that there are seasonal patterns to alopecia areata flares, and others have identified antihistamines as potentially helping in alopecia areata,” he said.
Methods
Ungar and colleagues used ICD-10-CM codes to identify four cohorts. The “any allergy cohort” included patients who were diagnosed with either a food or seasonal allergy. The “seasonal allergy cohort,” included patients with solely a seasonal allergy. The “food allergy cohort” included patients with only a food allergy. The “comorbid seasonal and food allergy cohort” included patients with diagnosed seasonal and food allergies.
The control cohort included patients without any allergy diagnosis. Cohorts were matched in a 1:1 ratio by index date and baseline demographics. The index date began at the first diagnosis of allergy and second general visit in the treatment and control cohorts.
Results
The patients in the any allergy group had an increased risk for alopecia areata (AA) as well as severe AA, with a hazard ratio of 1.4 (95% CI; 1.36-1.45) and 1.7 (95% CI, 1.51,1.91) respectively.
Patients in the seasonal allergy group were associated with an increased risk for AA with a hazard ratio of 1.41 (95% CI; 1.36-1.46) and severe AA (HR = 1.61; 95% CI, 1.42-1.84).
The food allergy group also had an increased risk for AA (HR = 1.10; 95% CI, 1.03-1.17), and for severe AA, (HR = 1.71; 95% CI, 1.33-2.20).
The comorbid seasonal and food allergy group showed the highest increased risk for AA with a hazard radio of 1.95 (95% CI; 1.78-2.13) and for severe AA (HR = 2.58; 95% CI, 1.91-3.50).
When compared with patients in the control group, patients with any allergy had an increased risk for AA with a hazard ratio of 1.28 (95% CI; 1.24-1.32) and for severe AA with a hazard ratio of 1.42 (95% CI; 1.26-1.6). The food allergy group also had a significantly risk for severe AA compared with the control group, with a hazard ratio of 1.28 (95% CI; 1.99-1.65).
Researchers also analyzed patients with IgE levels of greater than or equal to 200 versus less than 200 IU/mL and found that those with at least an IgE level of 200 IU/mL had a significantly increased risk for AA with a hazard ratio of 1.21 (95% CI; 1.02-1.43) and an increased risk for severe AA with a hazard ratio of 1.31 (95% CI; 0.87-1.97).
“The hypothesis going into this study was that having seasonal and/or food allergies may increase the risk of developing alopecia areata, which is what we found,” Ungar said.
He added that clinical implications of this link need to be further explored in order to understand how patients may benefit more from treatment such as additional evaluations of the use of antihistamines for AA.
“Better characterization of this connection may help efforts to shed light on the pathogenesis of alopecia areata,” he said.