Real-world retrospective study on allergy screening and its effect on specialist referral patterns

Accurate diagnosis of IgE-mediated diseases requires identifying relevant allergens to guide appropriate clinical management and reduce healthcare costs (1). The ImmunoCAP Phadiatop (Thermo Fisher Scientific) is an in vitro assay detecting that detects IgE antibodies against a balanced mixture of common inhalant allergens, serving as a first-level screening tool for sensitization in patients with suspected airway allergies, and guiding subsequent management. This study aimed to evaluate test results, the impact on clinical decision-making, and its role in managing allergic conditions.

A real-world retrospective observational study was conducted in a tertiary hospital allergy department (June 2021-June 2023). Data were collected using the Modulab Laboratory Information System (Werfen, Spain) and stored in a dissociated database. The Ethics Committee of Salamanca approved the study protocol. Phadiatop values above 0.35 PAU/l were considered positive. In case of repeated samples, the first was selected. Variables analyzed included test results, patient demographics, requesting departments, and allergy referrals, a well-balanced mixture of common inhalant allergens with regional adaptation. The allergen groups included were comprise: house dust mites, (e.g., Dermatophagoides pteronyssinus, D. farinae), pollens, from grasses (e.g., timothy, ryegrass), trees (e.g., birch, olive), and weeds (e.g., mugwort, plantain, ragweed), molds (e.g., Alternaria, Cladosporium, Aspergillus, Penicillium), and animal dander (e.g., cat, dog).

The study included 596 patients (median age 46, 64.1% female). Of these, 12.6% were under 18 years old. Most patients (95.8%) were referred from primary care, with 83.1% of them from urban areas. A total of 37.9% of patients had a positive result (median IgE 7.81 PAU/l). Most positive patients resided in urban areas (82.3%), were aged <18 years of age (p = 0.001), and were male (p < 0.001). Patients aged >59 (26.3%) presented mainly negative results (82.2%). Of the positive cases, 31.4% were referred to an allergist, with higher Phadiatop values increasing associated with increased referrals (p = 0.001).

Phadiatop was mainly utilized in primary care. One-third of patients tested positive; of those, only one-third were referred to allergists, with higher Phadiatop values increasing associated with higher referral rates. Positivity was higher in males and younger people.