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 ( < .001). Median platelet counts were higher by 30 × 10/μL in females with asthma when compared with males with asthma (median [interquartile range], 271.1 [235.0-312.0] vs 241.0 [209.0-279.4] × 10/μL, < .001, respectively). Among participants with asthma, higher platelet counts were also associated with increased asthma severity ( < .001). Platelet counts correlated positively with the blood absolute eosinophil count ( = 0.104, < .001), blood neutrophil count ( = 0.254, < .001), and C-reactive protein ( = 0.183, < .001).

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.