The sensitization feature of Cypress pollen in urban area of Beijing

Abstract

Objective: To explore the sensitization features of Cypress pollen in urban area of Beijing and analyze the seasonal changes. Methods: Four thousand two hundred and one patients in Department of Allergy of Beijing Shijitan Hospital during January to December 2017 were enrolled in this study and received skin prick test (SPT) of Cypress extract. Cypress sensitization was divided into two types: mono-sensitization and multiple-sensitization. Difference of sensitization rate between age, gender and visiting month was analyzed by chi-square test. Difference of visiting rate and sensitization rate among each month was analyzed by K-W test. Pearson test was carried out for correlation analysis. Results: Positive rate of Cypress pollen was 32.3% (1 358/4 201) in overall patients in which male had a higher positive rate than female (35.6% vs 30.1%, χ(2)=13.465, P<0.001). The positive rate was highest in age 11-20 years and 31-40 years and then decreased with age (P<0.001). Multi-sensitization was observed in this study with a rate of 27.5% (1 154/4 201) while mono-sensitization of Cypress was only 4.7% (199/4 201). The consultation rate during January to December was positively correlated with SPT positive rate of Cypress pollen (r(2)=0.715 9, P=0.001). The positive rate varied with season with the highest rate in March (53.0%, 316/596), followed by April (36.6%, 208/568). The season peak of positive rate was observed in adults but not children. Mono-sensitization rate varied with one season peak (spring) while multi-sensitization showed two season peaks (spring and autumn). Conclusion: Cypress sensitization is prevalent in urban area of Beijing and is prone to multi-sensitization, which changes with season with the peak in March.