Comparative study on severity and preventive behaviors of Japanese cedar pollen allergy during pollen scattering...

Hay fever cases, driven by factors such as global warming, are increasing globally, with Japanese cedar (JC) pollen being the primary allergen in Japan. While pharmacological therapies are available, their success heavily depends on patients' preventive behaviors, which remain poorly documented. This study examines the relationship between symptom severity and preventive behaviors during the JC pollen season.

This single-center, observational study included 161 new patients diagnosed with JC pollen allergy from January to March 2017. Patient data were collected through interviews and analyzed for severity using a five-point symptom scale and total Nasal Symptom Scores. Preventive behaviors, including preemptive antihistamine use, allergen immunotherapy, and pre-season consultations, were evaluated. Time-series analysis assessed trends in severe cases over the pollen season.

Patients who sought pre-season consultations were predominantly male (p = 0.006) and more likely to use preemptive antihistamines (p < 0.001) or allergen immunotherapy (p = 0.006). Severe symptoms were recorded in 38 patients, none of whom engaged in preventive behaviors, and only 10.5% sought pre-season consultations. Time-series analysis showed a daily increase of 6% severe cases after pollen season onset (p = 0.0064). Early preventive behaviors, such as preemptive antihistamine use (p = 0.007) and pre-season consultations (p < 0.001), significantly reduced severe cases.

The study highlights the importance of early preventive measures to reduce symptom severity and improve patient outcomes. Promoting preventive behaviors could alleviate the growing economic burden of hay fever and enhance public health strategies globally.