House Dust Mites and Grass Allergens Are Common Triggers for Atopic Dermatitis

September 24, 2020

D. farinae and D. pteronyssinus positive skin prick test results were much more frequent in patients >18 years.

Findings of a recent study showed house dust mites and grass allergens to be the most common triggers of atopic dermatitis. Furthermore, allergic rhinitis was found to be a comorbidity closely associated with the skin disease.

Currently, the global prevalence of atopic dermatitis stands at 20% in children and 3% in adults. The investigators of the study noted that although the disease is triggered by antigens, it is not clear which precise allergens are triggering factors.

Ömer Kutlu, MD, MRCP, and Ahmet Metin, MD, used file records from Kayseri Develi State Hospital of patients who underwent skin prick testing due to atopic dermatitis. They used the test results to determine the most common triggering allergens as well as any association with specific demographic factors.

Overall, they assessed 144 patients, with 73.6% being female. The median age of the population was 18 years (range, 3-51). Additionally, 63.2% of patients had a family history of allergic disease.

The skin prick test was administered by the same dermatologist so as to ensure standardization across all patients. Following administration of the test, positive results were evaluated and categorized into 4 levels of positivity degree– with 1 designating erythema ≤ 15 mm and no edema, and 5 designating edema > 6 mm as well as pseudopod development.

Thus, the investigators found that the most frequent allergens with ≥3 positivity (edema 3-6 mm), were grasses (31.2%), grasses mix (24.3%), Cynodon dactylon (15.3%), D. pteronyssinus (9.7%), D. farinae (7.6%), F. domesticus (7%), and Olea europaea (5.6%).

Furthermore, 65.3% of patients presented with a ≥1 degree of positivity, while 43.1% had a ≥3 positivity. Within both groups, 19.2% and 21.0%, respectively, demonstrated a reaction to only 1 allergen.

D. farinae and D. pteronysssinus positivity were much more frequent in patients >18 years than in those <18 years (P = 0.003 and P = .007, respectively). Besides these differences, there were no other statistical differences between other allergens and the age of the patients.

And finally, they found a statistical difference between ≥3 positivity and allergic rhinitis (P = .006). Additionally, those with allergic rhinitis were much likelier to have a ≥1 and ≥3 positivity.

Those with atopic dermatitis who had comorbid allergic rhinitis and a ≥3 positivity were more typically triggered by grasses (44.5%), grasses mix (37.0%), Cynodon dactylon (27.2%), D. farinae (9.9%), D. pteronyssinus (8.6%), and Canis familiaris (8.6%).

“Detection of allergens, particularly in patients with atopic dermatitis, is crucial for the treatment and prevention of the disease,” Kutlu and Metin emphasized.

They concluded by referencing previous literature that assessed the associations among specific characteristics, such as geographic locations, various types of allergens, and patients with atopic dermatitis. Yet, they noted there is still potential for more in-depth research.

“Further multicenter, comprehensive SPT [skin prick test] based studies on atopic dermatitis will illuminate the possible triggers of the disease in atopic dermatitis in different geographies,” they wrote.

The study, “Evaluation of Skin Prick Test Results in Patients with Atopic Dermatitis,” was published online in Eastern Journal of Medicine