Age dependent sex disproportion in US asthma hospitalization rates, 2000-2010.

Background: Age-stratified sex differences in asthma hospitalizations rates have been reported to be most marked between the ages of 40 and 54 years in New York. It is not known whether age-dependent sex differences in asthma hospitalization rates also exist for the entire United States.

Objectives: To compare sex-specific hospitalization rates for asthma in adults in the United States and to describe the adjusted associations between female sex and age in the fifth to sixth decades of life.

Methods: The National Inpatient Sample databases for 2000-2010 were queried for a principal diagnosis of asthma to calculate the ratio of female to male hospitalization rates for different decades of adult life. Logistic regression modeling was used to determine whether age in the fifth to sixth decades of life had associations with female sex that remained significant after adjusting for comorbidities and demographic features.

Results: For all years of the study, there was a distinct peaking in female to male ratio most manifested in the fifth to sixth decades of life. This age grouping was significantly associated with female sex. Models revealed that female sex was significantly associated with this age grouping, even after adjustment for obesity, chronic obstructive pulmonary disease, race, insurance status, discharge year, and smoking. Excluding identifiable repeat admissions also did not abrogate the age grouping association.

Conclusion: There is a striking propensity of women in their fifth to sixth decades of life to be admitted for asthma, which appears to be independent of many known comorbidities.