Increased platelet counts are associated with female sex and asthma severity.

Background: Significant sex differences occur in asthma phenotypes across the lifespan. Platelet activation is associated with a steroid-refractory asthma phenotype. Objective: We sought to test the hypothesis that higher platelet counts in females are associated with increased prevalence and severity of asthma compared with males. Methods: We conducted a cross-sectional analysis using data from participants' baseline visit in the UK Biobank. Binomial multivariable logistic regression was used to adjust for age, body mass index, sex, race, smoking status, serum C-reactive protein, absolute eosinophil count, and absolute neutrophil count. Results: Of the 351,203 patients included in the analysis, 5.7% had asthma, 2% met the British Thoracic Society criteria for moderate to severe asthma, and 57.4% were female. Female sex was associated with higher platelet counts among participants with or without asthma ( Conclusions: These findings suggest that platelet counts are associated with asthma and inflammation in both sexes and can serve as a potential biomarker for asthma severity with differential effects across the sexes. Future studies including mechanistic studies should characterize the interaction between sex hormones, platelet activation, and asthma severity.