Sex differences in asthma control: the HUNT study

Abstract

Background: Asthma control is hypothesized to be influenced by sex; however, studies investigating sex differences in asthma control are few and results are conflicting. Objective: To our knowledge, no published peer-reviewed studies have yet investigated sex differences in asthma control in Norway. We therefore aimed to compare the levels of asthma control between women and men in a large population-based cohort of Norwegian adults with asthma. Methods: We identified 3123 adults with self-reported physician-diagnosed asthma from the third survey of the Nord-Trøndelag Health Study (HUNT3) in Norway. We estimated odds ratios and 95% confidence intervals for poorly controlled asthma using multiple logistic regression models including 2214 individuals who had complete information on asthma control and model covariates. Model covariates were age (years), body mass index (kg/m2), current employment (employed/unemployed), smoking status (never- , ex-, occasional-, current smoker), physical activity (active/non-active) and Hospital Anxiety and Depression Scale score. We defined individuals as well controlled (per week; daytime symptoms ≤2 times, reliever medication ≤2 times, no night waking, no activity-limitation) or as poorly controlled (unfulfilling any aforementioned criteria) from HUNT3 questions coinciding with the Global Initiative of Asthma 2015 criteria of asthma symptom control. Results: The prevalence of poorly controlled asthma was 32.74% in women and 28.35% in men. Female sex was associated with poorly controlled asthma in a crude model (OR total control score; 1.23, 95% CI 1.02-1.48). Specifically, women were more likely to have daytime symptoms (OR 1.15, 95% CI 0.93 – 1.42), night awakenings (crude model OR 1.43, 95% CI 1.01 – 2.00), reliever medication need (OR 1.26, 95% CI 1.00 – 158) and activity limitations (OR 1.31, 95% CI 0.96 – 1.78) than men. These estimates changed slightly in an adjusted model to AOR 1.24, 95% CI 1.02 – 1.50 for total control score, to AOR 1.12, 95%CI 0.90 – 1.39 for daytime symptoms, to AOR 1.32, 95% CI 0.93 – 1.87 for night awakenings, to AOR 1.26, 95% CI 0.99 – 1.60 for reliever medication need and to AOR 1.25, 95% CI 0.91 – 1.72 for activity limitations. However we still observed a trend towards more uncontrolled asthma in women than men. Conclusion: We observed that women with asthma were more poorly controlled than men. More research is needed to ascertain what drives this sex difference. If sex is a determining factor of asthma control in Norway, this needs to be recognized in national asthma management. Keywords Asthma control Risk Factors Determinants Sex Global Initiative of Asthma HUNT3