Determinants of airflow limitation in Danish adults - findings from the Health2006 cohort

Background and aim: Airflow limitation may be found in patients with both asthma and COPD and is often associated with more symptoms and poorer outcome. We aimed to identify factors associated with airflow limitation in a well-characterized, population-based sample of adults.

Methods: From the Health2006 cohort, we selected participants aged ≥35 years at enrolment (n=2,959). Airflow limitation was defined as FEV1/FVC < lower limit of normal. Participants with (cases) and without (controls) airflow limitation were compared with regard to self-reported symptoms, medical history, atopy, lung function and exhaled nitric oxide. Between-group differences were analyzed using Chi-square and Mann-Whitney U tests, and effect size was estimated by logistic regression (reported as OR and 95% CI).

Results: We identified 313 cases, majority of which were female, reported poor overall health, physically inactivity and experienced respiratory symptoms within the previous year. The presence of airflow limitation was associated with BMI (OR 3.1 for overweight, P<0.001, CI 1.97-4.78), age (OR 2.3, P<0.001 for age 55+, CI 1.7-3.2), tobacco exposure (OR 1.6, P=0.01, CI 1.1-2.32, and OR 1.76, P=0.019, CI 1.2-2.3 for former and current smokers, respectively), sex (OR 1.6 for being female, P=0.002, CI 1.2-2.2), presence of specific IgE to common aeroallergen(s) (OR 1.4, P=0.041, CI 1.2-2.0), and ever being diagnosed with asthma (OR 1.6, P=0.003, CI 1.3-2.0).

Conclusion: Apart from tobacco exposure and age, the presence of airflow limitation was associated with being overweight, female, sensitized to common aeroallergens or ever having a diagnosis of asthma.