Eva Rönmark

Background: Aeroallergen sensitization is a major factor in asthma, and asthma is associated with impaired lung function. The independent association between sensitization and lung function is unclear.Objectives: To examine factors associated with lung function in adolescence, with special interests in sensitization and asthma.Methods: All schoolchildren in grade one and two (median age 8) in two municipalities in Northern Sweden were invited to a questionnaire survey of allergic diseases and skin prick tests to aeroallergens. This was repeated at ages 12 and, at 19 years also including spirometry and n = 1495 participated at all three occasions. Associations between risk factors and FEV₁, FVC and FEV₁/FVC were analysed by linear regression.Results: Aeroallergen sensitization was not associated with lung function, irrespective of age at onset, type or degree of sensitization. Early‐onset asthma, both persistent (B −0.35, 95% CI –0.60 to −0.09) and in remission (B −0.43, 95% CI –0.74 to −0.12) was associated with lower FEV₁. Persistent asthma was associated with lower FEV₁/FVC (B −0.81, 95% CI –1.07 to −0.55), and remission with lower FVC (B −0.37, 95% CI –0.67 to −0.70). No interaction between asthma and sensitization was found. Maternal smoking in pregnancy was associated with lower FEV₁/FVC. Underweight at age 19 years was associated with lower FEV₁ and FVC and overweight was associated with higher FEV₁ and FVC, but lower FEV₁/FVC.Conclusions: Aeroallergen sensitization was not independently associated with lung function. Early onset asthma was strongly associated with lung function impairments in young adulthood and in sensitized and non‐sensitized individuals alike.

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 (FEV ₁ )/forced vital capacity (FVC) 1 /FVC 1 /FVC 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 FEV ₁ /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: Longitudinal studies on allergic rhinitis (AR) incidence and remission from childhood to adulthood are limited. This study aimed to estimate AR incidence and remission from age 8 to 19 years and to identify related risk factors. Methods: In 2006, all children in grades 1 and 2 (median age 8 years) in three municipalities in Northern Sweden were invited to participate in a questionnaire survey. The children in two of the municipalities underwent a skin prick test (SPT) for airborne allergens. The protocol was repeated at age 19 years. In total, 2250 participants (91% participation rate) completed the questionnaire, and 1338 underwent SPTs at 8 and 19 years of age. Results: From age 8 to 19 years, the cumulative incidence of AR was 33.6%, significantly higher among girls than boys (37.4% vs. 29.8%, p < .001). Factors that independently increased the risk of developing AR were sensitisation by age 8 (adjusted odds ratio [aOR] 3.75, 95% confidence interval [CI] 2.68–5.23), sensitisation between 8 and 19 years (aOR 2.57, 95% CI 1.82–3.63), and female sex (aOR 1.71, 95% CI 1.30–2.26). The remission rate was 40.0%, with boys experiencing significantly higher remission than girls (45.4% vs. 32.2%, p = .015). The probability of remission was decreased by sensitisation before (aOR 0.26, 95% CI 0.13–0.53) and after age 8 years (aOR 0.20, 95% CI 0.05–0.77). Conclusion: This study found a high incidence of AR between age 8 and 19 years, especially among girls, while boys had a higher remission rate. Sensitisation increased the risk of developing AR and decreased the remission rate.

Background: Asthma is strongly associated with impaired LF, and allergic sensitization (AS) is a known risk factor for asthma, but the association between AS and LF is not clarified. Aim: To examine determinants of LF in adolescence, with special interest in allergic sensitization. Methods: In 1996, all schoolchildren in grade one and two, median age 8 years, in two municipalities in Northern Sweden was invited to a questionnaire survey of allergic diseases and skin prick tests (SPT) to 10 airborne allergens. Invitations were repeated at ages 12 and, at 19 years also including spirometry. Participating rate at all three occasions was 1495 (70% of participa age 8). Associations between exposures and spirometry indices were analysed by students t-test and linear regression. Results: AS was not associated with LF, irrespective of age at onset, type, or degree of sensitization. Early onset asthma, both persistent (β -0.35, 95% CI –0.60- -0.09) and in remission (β -0.43, 95% CI –0.74- -0.12) was associated with reduced FEV1. Persistent asthma was associated with reduced FEV1/FVC (β -0.81, 95% CI –1.07- -0.55), and remission with reduced FVC (β -0.37, 95% CI –0.67- -0.70). Maternal smoking in pregnancy was associated with lower FEV1/FVC, while own smoking was not. Underweight was associated with marked reduced FEV1 and FVC. Overweight was associated with slight increases in FEV1 and FVC. The results remained in analyses restricted to those without asthma. Conclusion: AS was not independently associated with LF, despite being an important risk factor for asthma. Early-onset asthma was associated with LF impairments also among those in remission.

Background: The prevalence of asthma has increased both among children and adults during the latter half of the 20th century. The prevalence among adults is affected by the incidence of asthma in childhood but also in adulthood. Time trends in asthma incidence are poorly studied. The aim was to study the incidence of asthma among adults from 1996-2006 and 2006-2016, and compare the risk factor patterns. Methods: Within the Obstructive Lung Disease in Northern Sweden (OLIN) studies, two randomly selected population-based samples in ages 20-69 years participated in postal questionnaire surveys about asthma in 1996 (n=7104, 85%) and 2006 (n=6165, 77%), respectively. A 10-year follow-up of the two cohorts with the same validated questionnaire was performed, and n=5709 and n=4552, respectively, responded. Different definitions of population at risk were used in the calculations of asthma incidence. The protocol followed a study performed 1986 to 1996 in the same area. Results: The crude incidence rate of physician-diagnosed asthma was 4.4/1000/year (men 3.8, women 5.5) from 1996-2006, and 4.8/1000/year (men 3.7, women 6.2) from 2006-2016. When correcting for possible under-diagnosis at study entry, the incidence rate was 2.4/1000/year from 1996-2006 and 2.6/1000/year from 2006-2016. The incidence rates were similar across age groups. Allergic rhino-conjunctivitis was the main risk factor for incident asthma in both observation periods (risk ratios 2.4-2.6). Conclusions: The incidence of asthma among adults has been stable over the last two decades, and on similar level since the 1980s. The high incidence contributes to the increase in asthma prevalence.

Introduction: How e-cigarette use relates to changes in smoking status and respiratory symptoms in the population remains controversial. The aim was to study the association between e-cigarette use and, changes in smoking status and changes in respiratory symptoms. Methods: A prospective,...

Rationale: Spirometry is essential for diagnosis and assessment of prognosis in patients with chronic obstructive pulmonary disease (COPD). Objectives: To identify FEV1 trajectories and their determinants on the basis of annual spirometry measurements among individuals with and without airway obstruction (AO) and to assess mortality in relation to trajectories. Methods: From 2002 through 2004, individuals with AO (FEV1/VC < 0.70, n = 993) and age- and sex-matched nonobstructive (NO) referents were recruited from population-based cohorts. Annual spirometry until 2014 was used in joint-survival latent-class mixed models to identify lung function trajectories. Mortality data were collected during 15 years of follow-up. Measurements and Main Results: Three trajectories were identified among the subjects with AO and two among the NO referents. Trajectory membership was driven by baseline FEV1% predicted (FEV1%pred) in both groups and also by pack-years in subjects with AO and current smoking in NO referents. Longitudinal FEV1%pred depended on baseline FEV1%pred, pack-years, and obesity. The trajectories were distributed as follows: among individuals with AO, 79.6% in AO trajectory 1 (FEV1 high with normal decline), 12.8% in AO trajectory 2 (FEV1 high with rapid decline), and 7.7% in AO trajectory 3 (FEV1 low with normal decline) (mean, 27, 72, and 26 ml/yr, respectively) and, among NO referents, 96.7% in NO trajectory 1 (FEV1 high with normal decline) and 3.3% in NO trajectory 2 (FEV1 high with rapid decline) (mean, 34 and 173 ml/yr, respectively). Hazard for death was increased for AO trajectories 2 (hazard ratio [HR], 1.56) and 3 (HR, 3.45) versus AO trajectory 1 and for NO trajectory 2 (HR, 2.99) versus NO trajectory 1. Conclusions: Three different FEV1 trajectories were identified among subjects with AO and two among NO referents, with different outcomes in terms of FEV1 decline and mortality. The FEV1 trajectories among subjects with AO and the relationship between low FVC and trajectory outcome are of particular clinical interest.

Background: The prevalence of atopic dermatitis (AD) has increased over several decades and now affects about one-fifth of all children in high-income countries (HICs). While the increase continues in lower-income countries, the prevalence of AD might have reached a plateau in HICs. Objectives: To investigate trends in the prevalence of AD and atopic comorbidity in schoolchildren in Sweden. Methods: The study population consisted of three cohorts of children (median age 8 years) in Norrbotten, Sweden, for 1996 (n = 3430), 2006 (n = 2585) and 2017 (n = 2785). An identical questionnaire that included questions from the International Study of Asthma and Allergies in Childhood (ISAAC) protocol was used in all three cohorts. Trends in AD prevalence were estimated, as well as trends in atopic comorbidity. AD prevalence was estimated both according to the ISAAC definition of AD and by adding the reported diagnosis by a physician (D-AD). Results: The prevalence of AD decreased in the last decade, from 22.8% (1996) and 21.3% (2006) to 16.3% (2017; P < 0.001). The prevalence of D-AD was lower, but the same pattern of decrease was seen, from 9.3% (1996) and 9.4% (2006) to 5.7% (2017; P < 0.001). In all three cohorts, AD was more common among girls than boys (18.9% vs. 13.8% in 2017; P < 0.001). Children from the mountain inlands had a higher prevalence of AD than children from coastal cities (22.0% vs. 15.1% in 2017; P < 0.001). In comparing D-AD, there were no significant differences between the sexes or between inland or coastal living. Concomitant asthma increased over the years from 12.2% (1996) to 15.8% (2006) to 23.0% (2017; P < 0.001). Concomitant allergic rhinitis and allergic sensitization increased from 1996 (15.0% and 27.5%) to 2006 (24.7% and 49.5%) but then levelled off until 2017 (21.0% and 46.7%). Conclusions: The prevalence of AD among schoolchildren in Sweden decreased over the study period, whereas atopic comorbidity among children with AD increased. Although a decrease was seen, AD is still common and the increase in atopic comorbidity among children with AD, especially the increase in asthma, is concerning.