Umeå University's logo

In this study, we compared symptoms, comorbidities, and healthcare burden between childhood-onset asthma (< 18 years) and early adult-onset (18–39 years) and late adult-onset asthma (≥ 40 years). Among 3546 participants with data on physician-diagnosed asthma and onset age, 46.4% were defined as adult-onset [864 (24.4%) had early adult-onset asthma (18–39 years) and 782 (22.1%) had late adult-onset asthma (≥ 40 years)], which, compared to childhood-onset asthma, presented with more complex, multi-symptom profiles, including productive cough, sputum production, but less wheezing. Allergy-related comorbidities were more common in childhood-diagnosed asthma, while chronic obstructive pulmonary disease (COPD), diabetes mellitus, hypertension, obesity, and chronic sinusitis were more common in adult-onset asthma. Adult-onset asthma also had a higher disease burden, with more frequent medication use and exacerbations. Adult-onset asthma has an underlying complexity, contributing to a vicious cycle of worsening symptoms, increased medication use, and more comorbidities.

Background: Asthma severity is influenced by complex immunologic and environmental factors. While allergic asthma is linked to increased susceptibility to respiratory infections, the combined role of allergy and antibiotic-treated infections in progression to severe asthma has not been fully evaluated.

Objective: To evaluate whether allergic asthma and recurrent respiratory infections (RRI) requiring antibiotics are associated with increased risk of developing severe asthma.

Methods: We conducted a registry-based cohort study using Swedish national registry data. Adults with mild-to-moderate asthma were identified in 2014 (baseline) based on prescription records and absence of severe disease indicators. During a two-year exposure window (2015–2016), RRI was defined as ≥ 2 antibiotic prescriptions for lower respiratory tract infections. The outcome was development of severe asthma during 2017–2019, based on ERS/ATS treatment criteria. Allergic asthma was defined by ≥ 2 prescriptions for anti-allergic medications at baseline.

Results: Among 113,393 patients, 24,692 (21.8%) had allergic asthma. RRI occurred more frequently in allergic versus non-allergic asthma (7.5% vs. 5.9%, p < 0.001). A total of 869 patients (0.77%) developed severe asthma. Incidence was higher in those with RRI and highest among patients with both allergic asthma and RRI (2.0%), corresponding to a relative risk of 3.47 (95% CI: 2.49–4.83) versus patients with neither exposure. Results were consistent after adjustment for age, sex and comorbidities.

Conclusion: Allergic asthma and antibiotic-treated respiratory infections were independent and additive predictors of severe asthma progression. These findings support a clinically actionable risk profile and may inform targeted preventive strategies in asthma management.

Purpose: Asthma control is multifaceted, involving symptoms and risk of adverse outcomes. Emerging evidence suggests a bidirectional link between poor asthma control and severe COVID-19, but large studies addressing all components of asthma control in this context are lacking. Our aims were to evaluate if 1) uncontrolled asthma was a risk factor for COVID-19 hospitalization and death, 2) asthma control changed during the pandemic and 3) COVID-19 hospitalization was a risk factor for future uncontrolled asthma.

Methods: Patients with asthma (n = 125,362) were identified in the Swedish National Airway Register from January 2014 to 2020, whereof n = 2377 were hospitalized and n = 305 died due to COVID-19 during follow-up until December 2022. Asthma control was evaluated by symptoms (Asthma Control Test (ACT) ≥ 20: well controlled, ACT 16–19 not well-controlled and ACT < 16 very poorly controlled asthma), lung function (FEV1% predicted (pp)) and frequent and/or severe exacerbations (dispensed oral corticosteroids and asthma inpatient care).

Results: ACT 16–19 (RR 1.57, 95% CI 1.34–1.84), ACT < 16 (1.72, 1.46–2.02), FEV1 < 80pp (1.29, 1.13–1.48), frequent (1.99, 1.79–2.21) and severe exacerbations (2.54, 2.09–3.08) were associated with a higher risk for COVID-19 hospitalization. COVID-19 death was associated with ACT < 16, frequent and severe exacerbations. Overall, at follow-up, proportions of ACT < 20 (36.1%) and FEV1 < 80pp (48.3%) were stable, while exacerbations decreased (frequent; 7.9% to 6.8%, severe; 1.3% to 0.4%). COVID-19 hospitalization was a risk factor for frequent (1.35, 1.22–1.51) and severe (3.42, 1.22–1.51) future asthma exacerbations.

Conclusion: All dimensions of poor asthma control were associated with an increased risk of severe COVID-19. In contrast, only exacerbation risk was elevated following COVID-19.

Background The extent to which airflow obstruction, a key feature of COPD, can be already present in early adulthood is unclear. We investigated the prevalence of airflow obstruction in young adults across European populations.

Methods We identified 48 612 individuals aged 20–40 years across eight population-based European cohorts in the Chronic Airway Diseases Early Stratification (CADSET) collaboration and applied two commonly used definitions of airflow obstruction: pre-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) <0.70 and below the lower limit of normal (LLN). We explored how the prevalence of airflow obstruction according to both criteria was related to age, sex and smoking.

Results Airflow obstruction prevalence increased with increasing age from 2.3% in those aged 20–24.9 years to 6.3% in those aged 35–39.9 years according to FEV1/FVC <0.70, and from 7.3% to 8.3% according to FEV1/FVC <LLN. The corresponding increase in airflow obstruction prevalence was up to 8.8% in males versus 7.5% in females, and up to 9.0% in ever-smokers versus 6.9% in never-smokers. Difference in prevalence of airflow obstruction between FEV1/FVC <0.70 and <LLN was highest for females and ever-smokers. Active smoking ranged from 19% to 28% and ever-smoking from 37% to 51%. The prevalence of airflow obstruction increased with pack-years, plateauing at ∼5 pack-years.

Conclusion Up to 8% of young adults across Europe have airflow obstruction; its cause and its role in prior, concurrent and future airway disease merit further investigation.

Background: Respiratory symptoms are common in the general adult population. Increased burden of respiratory symptoms may increase the risk of mortality. We assessed the association between respiratory symptom clusters and mortality.

Methods: Participants were derived from two population-based Swedish adult cohorts (N = 63,060). Cluster analysis was performed with Locality Sensitive Hashing (LSH)-k-prototypes in subjects with ≥ 1 self-reported respiratory symptom. Linked mortality register data (up to 21 years of follow-up, > 600,000 person-years) were used. Associations between clusters and all-cause/cause-specific mortality were assessed using asymptomatic subjects as reference.

Results: Over 60% reported ≥ 1 respiratory symptom and ~ 30% reported ≥ 5 respiratory symptoms. Five clusters were identified, partly overlapping with established respiratory disease phenotypes but many individuals were undiagnosed: (1) "low-symptomatic" (30.3%); (2) "allergic nasal symptoms" (10.7%); (3) "allergic nasal symptoms, wheezing, and dyspnea attacks" (4.7%); (4) "wheezing and dyspnea attacks" (6.6%); (5) "recurrent productive cough and wheezing" (4.1%). All but Cluster 2 were associated with all-cause mortality, highest risk for Cluster 3 (hazard ratio 1.4, 95% confidence interval 1.13–1.73) and Cluster 5 (1.4, 1.22–1.61). Comparable associations were seen for cardiovascular mortality. For respiratory mortality, Cluster 4 (2.02, 1.18–3.46) and Cluster 5 (1.89, 1.1–3.25) were most strongly associated.

Conclusions: Respiratory symptoms are common in the general adult population, with identifiable clusters. These clusters have clinical relevancy as they are differentially associated with mortality and relatively weakly correlated with diagnosed respiratory disease.

Background: The use of blood eosinophil count (BEC) as a prognostic biomarker in the management of conditions such as asthma and chronic obstructive pulmonary disease (COPD) may be complicated by factors such as atopy, age, sex, smoking, and comorbidities. Objective: We sought to produce reference values for BEC, considering age, asthma, COPD, and clinical allergy for the general adult population. Methods: The West Sweden Asthma Study constitutes a population-representative clinical epidemiological cohort of randomly selected adults in Western Sweden. From this cohort, 1145 individuals took part in clinical examinations, including skin prick testing, specific IgE, and BEC. Results: The upper limit (95th percentile) of BEC varied by age. It ranged from 400 to 500 cells/μL in the full sample and from 300 to 400 cells/μL in subjects without asthma, COPD, and clinical allergy (n = 710). Sex, smoking, atopy, clinical allergy, obesity, asthma, COPD, diabetes, and hypertension were statistically significantly associated with higher BEC levels. However, only asthma and clinical allergy in the full sample, and obesity and diabetes in those without asthma, COPD, or clinical allergy, remained statistically significant with higher BEC levels in multivariable regression analyses. Conclusions: In a population-representative sample, the upper limit of BEC in healthy adults ranged between 300 and 400 cells/μL, varying by age. Age, smoking, obesity, asthma, COPD, and clinical allergy influence BEC levels and should be considered in clinical interpretation.

Background: Individuals with a restrictive spirometric pattern have a high burden of cardiovascular and metabolic morbidity.

Objective: To assess prevalence of elevated cardiac biomarkers among individuals with a restrictive spirometric pattern compared to those with a normal lung function and to evaluate the association between cardiac biomarkers and mortality.

Methods: In 2002–04, individuals with airway obstruction were identified from population-based cohorts, together with age- and sex-matched non-obstructive referents. The analysis population consisted of the non-obstructive referents stratified according to whether they had a restrictive spirometric pattern or normal lung function in whom cardiac biomarkers were measured. Deaths were recorded until 31 December 2010.

Results: Participants with a restrictive spirometric pattern were older and more likely to be obese with a higher burden of cardiovascular risk factors than those with normal function. Elevated cardiac troponin but not natriuretic peptide levels were more common in those with a restrictive spirometric pattern independent of age, sex, BMI, or risk factors (adjusted OR 1.8, 95% CI 1.29–2.74). At 5 years, death occurred more frequently in participants with restrictive spirometric pattern compared to those with normal function (15.7% [31/197] versus 7.6% [57/751]), with highest mortality rate in those with restriction and elevated cardiac troponin (28.7% [27/94]). Cardiac troponin was independently associated with death among those with a restrictive spirometric pattern (HR 4.91, 95% CI 1.58–15.26) but not in those with normal lung function.

Conclusion: Cardiac troponin was elevated more often in people with a restrictive spirometric pattern in whom it was a strong independent predictor of death.

Background: The “type 2 (T2)-high” phenotype has a relatively well-defined pathophysiology compared with “T2-low” asthma. T2-low asthma has been mostly studied among severe asthma cases. Objective: To estimate the proportion and assess the clinical features of asthma with low T2 markers in a general asthma population, including all severities.

Methods: Participants with current asthma from the population-based adult West Sweden Asthma Study were included. High T2 markers were defined as the blood eosinophil count ≥0.15 × 109/L or fractional exhaled nitric oxide ≥20 parts per billion or asthma being allergen driven. If none of these were present, the case was considered as asthma with low T2 markers.

Results: In total, 896 participants were included, of whom 14.3% had low T2 markers. The low T2 marker group had female predominance and had later asthma-onset age compared with the high T2 marker group. Participants with low T2 markers had better spirometry results in terms of airflow obstruction parameters but had more asthma-related emergency visits in the past 12 months than those with asthma with high T2 markers.

Conclusions: In a general adult asthma population, 1 in 7 individuals have low T2 markers according to the criteria used in this study. Importantly, these individuals had better lung function than individuals with high T2 markers but a significantly increased risk of asthma exacerbations. Thus, having asthma with low T2 markers is an independent risk factor for exacerbations, which should be considered when assessing patients with asthma clinically.