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Introduction Lung function development from childhood to young adulthood is important for lung health later in life. We investigated the association between asthma control and lung function from 8 to 24 years of age. Methods A total of 668 participants from the population-based BAMSE cohort study, with persistent or incidental asthma and between 8 and 24 years of age, were included. Asthma was defined as controlled or uncontrolled at each examination based on the Global Initiative for Asthma (GINA) criteria. Dynamic spirometry was performed at 8, 16 and 24 years of age. Associations between uncontrolled asthma and pre-bronchodilation forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio were evaluated with a generalised estimating equation model, as overall associations and at each examination. Unadjusted and adjusted (for sex, current asthma, allergic sensitisation, body mass index, smoking, smoke exposure, inhaled corticosteroid use) analyses were done; and were thereafter stratified by sex, elevated blood eosinophils (≥0.3×109 cells·µL−1), elevated FENO (≥25 ppb), allergic sensitisation and ever/never smoking. Results Uncontrolled asthma was associated with a lower overall FEV1/FVC z-score from 8 to 24 years of age (adjusted regression coefficient −0.11; 95% CI (−0.20 to −0.02; p=0.016). After stratification, this association was primarily seen among females (adjusted regression coefficient −0.170; 95% CI (−0.298 to −0.044; p=0.009) and participants with elevated FENO (regression coefficient −0.207; 95% CI −0.342 to −0.073; p=0.002), in contrast to males and participants with normal FENO. Conclusion Uncontrolled asthma is associated with airflow obstruction from childhood to young adulthood. This highlights the importance of active management of asthma during growth., Uncontrolled asthma from 8 to 24 years of age is associated with a lower overall FEV1/FVC z-score. Intensified treatment of symptomatic asthma, especially asthma with elevated FENO and in females, could have important implications for future lung health. https://bit.ly/3pHkleN

IOS assess the mechanical properties of the respiratory system. The method is sensitive to identify early changes, but adequate reference values are needed for clinical use. Therefore we studied how the producer’s recommended reference values (Vogel 1994) fit individuals from SCAPIS. Furthermore, we evaluated the burden of respiratory symptoms in relation to abnormal IOS. IOS was done in 5036 (51% female) individuals aged 50-64 years from the Uppsala center of SCAPIS. Values above 95th percentile for resistance at 5 Hz (R5) and lower values than 5th percentile for reactance at 5 Hz (X5) were used to defined cut-offs for impaired R5 and X5 in healthy, never smokers (n=1887, 46% female). The prevalence of impaired R5 and X5 was 10 and 11.4%, respectively, of the general population, while corresponding numbers using the Vogel were 5.8% and 3.7%. Subjects with R5 normal according to Vogel, but impaired according to SCAPIS (n=170) had a higher burden of wheeze (12.0% vs 5.8%,) dyspnea (14.9% vs 6.3%), and self-reported asthma (12.3% vs 7.9%) compared to subjects with normal R5 according to both Vogel and SCAPIS (n=3426) (all p Using the producer’s recommended reference values, fewer individuals will have an impaired lung function measured by IOS, compared to population-defined normal range in SCAPIS. Individuals with abnormal IOS according to SCAPIS, but normal according to producer’s reference values, have a higher burden of respiratory disease. This suggests clinical implications of choosing adequate reference equations.

Background: Air pollution (AP) exposure during infancy can affect lung function later in childhood and adolescence. However, few studies have investigated the effect of AP exposure on lung function in infancy. Aims: To investigate infant lung function in relation to exposure to PM2.5, PM10 and NO2 in an area with comparatively low pollution levels. Methods: Using birth registers, healthy infants residing in Stockholm city were recruited to one cohort (n=99) between 2014 and 2017. Another cohort (n=78) also included healthy infants recruited from maternity wards between 2009 and 2011 in Stockholm County. Forced expiratory maneuvers were performed in both cohorts. In pooled analyses of the two cohorts lung function measures at about 6 months of age were related to time-weighted average AP levels at residential addresses from birth and onwards using linear regression with inclusion of potential confounding variables. Results: There was a significant inverse relation between AP exposure and FEV0.5 as well as FVC at 6 months of age. Conclusion: Air pollution exposure was associated with impaired infant lung function measures related to both obstructive and restrictive airway disease.

Background: Little is known about the prevalence and early life risk factors for chronic bronchitis in young adults. Methods: Questionnaire data on respiratory symptoms and lung function from the 24-year follow-up of the Swedish BAMSE cohort were used. We assessed chronic bronchitis (CB) as the combination of cough and mucus production in the morning during winter. Environmental and clinical data collected at 0, 4, 8 and 16 years were used for analyses of risk factors. Results: At the 24 years follow-up, 75% (n=3064) participants completed the questionnaire and 2030 performed lung function measurements. The overall prevalence of CB was 5.5% (n=158) with no difference between males and females. 41% of CB cases had concurrent asthma compared to 11% of subjects without CB (p Conclusion: In the BAMSE cohort, the population-based prevalence of CB was 5.5% in young adults below age 25 years. Recurrent respiratory infections were common in these subjects. Active smoking as well as early environmental exposures were potential risk factors for CB.

Background: Extremely preterm birth before 28 weeks of gestation is a risk factor for chronic lung morbidity. Lung function follow up is therefore important in this group. Dynamic spirometry is the most widely used method, but impulse oscillometry (IOS) has been shown to be easier to perform in young children. Correlation between spirometry and IOS parameters has not been investigated in children born extremely preterm. Aim: To investigate the feasibility of performing, and to evaluate the correlation between spirometry and IOS outcomes in 6 year-old-children born extremely preterm. Methods: Spirometry and IOS were performed according to ERS guidelines in 6-year old children born extremely preterm (n=88) and term controls (n=84) in Stockholm, Sweden. Correlation between IOS and spirometry parameters were analyzed in the preterm group using Pearson’s partial correlation adjusting for height. Results: Success rates for spirometry and IOS did not differ significantly between the preterm and term groups (93% and 94% for IOS, p=0.79; 57% and 64% for spirometry, p=0.33). Spirometry and IOS outcomes correlated significantly in the preterm group, where the strongest estimates were found between Forced Expiratory Volume at 0.75 seconds (FEV0.75) and Reactance area (Ax), Table 1. Conclusion: Our results suggest that young children born extremely preterm have the same difficulties in performing spirometry as children born term. Further, spirometry and IOS parameters correlate significantly in children born extremely preterm.

Background: Traffic related air pollution (TRAP) is a well-known risk factor for lung disease. In particular, exposure during infancy has been shown to affect lung function later in childhood. However, there are few studies investigating the effect on lung function in infancy. Aims and Objectives: To investigate lung function in infancy in relation to TRAP exposure, hypothesizing that the effect on lung function is apparent already in infancy. Methods: Through a combination of birth registers and address based exposure assessment a total of 99 infants resident within Stockholm city at addresses with low (PM10 Results: There were no significant differences in lung function between infants with low and high levels of TRAP exposure (Table 1). *Maximal forced expired flow at functional residual capacity #Forced expiratory volume at 0.5 seconds Conclusion: Using a binary indicator of TRAP exposure, we found no significant effects on lung function at six months of age. This may have to do with comparatively low levels of air pollution in Stockholm.

Introduction: BPD in infants born preterm is a risk factor for respiratory disease in adulthood. Aims: To evaluate lung function in young adults born preterm with and without a history of BPD compared to mild allergic asthmatics and healthy controls from the LUNAPRE cohort (clinicaltrials.gov/ct2/show/NCT03049202). Methods: Twenty-six individuals with a history of BPD, 23 age-matched individuals born preterm without diagnosis of BPD, 23 individuals with mild allergic asthma and 24 healthy controls were recruited in the study (mean age 19.9 years; range 18.2-23.8). All subjects were examined using dynamic spirometry, multiple breath wash-out, and diffusion capacity of the lung (DLCO). Symptoms were scored using St George9s Respiratory Questionnaire (SGRQ). Results: Young adults with a history of BPD had lower FEV1 than preterm without BPD, (-0.94 vs. 0.28 z-scores; p ≤0.001); mild allergic asthmatics (0.14 z-scores, p ≤ 0.01) and healthy controls (0.78 z-scores, p≤0.001). The FEV1/FVC ratio was lower in the BPD-group compared to preterm without BPD (p ≤0.001), asthmatics (p=0.08) and healthy controls (p ≤0.001). The BPD-group had a higher lung clearance index than healthy controls (7.0 vs. 6.5, p≤0.001). Both preterm groups had lower DLCO compared to healthy controls (p≤0.001 for both). However, the SGRQ score was lower in the BPD-group compared to those with asthma (6.3 vs 16.5; p≤0.001). Conclusions: Adults with a history of BPD had obstructive lung function impairment including involvement of small airways. Despite more airway obstruction, the individuals in the BPD-group expressed less symptoms than those with mild asthma, highlighting the need for objective assessment of lung health in this group.

Introduction: Bronchopulmonary dysplasia (BPD) is a risk factor for respiratory disease in children born preterm. Aims: To extensively evaluate lung function in prematurely born adolescents with and without BPD in infancy and to assess change over time from school age. Methods: Fifty-one individuals born between gestational weeks 24 to 31 in Stockholm, Sweden, were examined in adolescence (12-15 years of age) using spirometry, impulse oscillometry, plethysmography, multiple breath wash-out and ergospirometry. Comparison with spirometry and impulse oscillometry data from school age (6-8 years of age) was also made. Twenty-three infants were diagnosed with respiratory distress syndrome but not BPD, while 28 were graded as mild (n=17), moderate (n=7) and severe (n=4) BPD. Results: Adolescents with a history of BPD, had lower forced expiratory volume in 1 sec (-0.80 vs. -0.02 z-scores, p 5-20 , (0.11 vs. 0.063 kPa/L / s, p p 1 /FVC z-scores decreased for all groups, especially in the group with severe BPD (-2.95 z-scores , 95%CI -3.42;-1.42 at 12-15 years). Conclusions: Lung function reflecting the central and the peripheral airways were affected in adolescents previously diagnosed with BPD. The further reduction of the FEV 1 /FVC-ratio over time in the group with severe BPD might implicate a route towards chronic airway obstruction. Our results suggest the need for follow up of lung function in adulthood.

Background: Asthma in combination with rhinitis and eczema has been suggested to be associated with worse lung function than isolated asthma. Aim: To examine associations between asthma with and without rhinitis, eczema, allergic sensitization and; (1) spirometry, and (2) small airway involvement measured by impulse oscillometry (IOS). Methods: In the Swedish population-basedbirth cohort BAMSE (n= 4089), we used questionnaire data to identify children with rhinitis, eczema and asthma at 16 yrs. Sensitization was defined asspecific IgE ≥0.35 kU A /L. Subjects with asthma, with and without comorbidities, where compared to subjects without disease. Results: Asthma with and without rhinitis or eczema resulted in similar negative associations with FEV1/FVC (only asthma -2.6 %-units, 95% CI -3.9;-1.6, asthma + rhinitis -2.3, -3.4;-1.3). No significant associations were seen between isolated rhinitis/eczema and spirometric indices. Associations with increased peripheral resistance in the small airway resistance index R 5-20 was observed only for asthma in combination with rhinitis, but not for isolated asthma, rhinitis or eczema. Further analyses to assess the relationship between small airway involvement, asthma, rhinitis and sensitization status showed significant associations with R 5-20 only for asthma with sensitization, independent of rhinitis status (p= 0.438 for asthma + rhinitis without sensitization and p= 0.001 for asthma + rhinitis with sensitization). Conclusions: Asthma with allergic sensitization is associated with small airway involvement measured by IOS. Rhinitis and eczema did not alter the negative associations between asthma and lung function once sensitization was taken into account.