Per Thunqvist

Early-Life Exposure to Traffic-related Air Pollution and Lung Function in Adolescence

RATIONALE Exposure to air pollution during infancy has been related to lung function decrements in 8-year-old children, but whether the negative effects remain into adolescence is unknown. OBJECTIVES To investigate the relationship between long-term air pollution exposure and lung function up to age 16 years. METHODS A total of 2,278 children from the Swedish birth cohort BAMSE (Children, Allergy, Milieu, Stockholm, Epidemiological Survey) performed spirometry at age 16 years. Levels of outdoor air pollution from local road traffic were estimated (nitrogen oxides [NOx] and particulate matter with an aerodynamic diameter of <10 μm [PM10]) for residential, daycare, and school addresses during the lifetime using dispersion modeling. Associations between exposure in different time windows and spirometry indexes were analyzed by linear regression and mixed effect models. MEASUREMENTS AND MAIN RESULTS Exposure to traffic-related air pollution during the first year of life was associated with FEV1 at age 16 years of -15.8 ml (95% confidence interval [CI], -33.6 to 2.0 for a 10 μg/m(3) difference in NOx), predominately in males (-30.4 ml; 95% CI, -59.1 to -1.7), and in subjects not exposed to maternal smoking during pregnancy or infancy. Later exposures appeared to have had an additional negative effect. High exposure during the first year of life was also associated with odds ratios for FEV1 and FVC less than the lower limit of normal (LLN) (defined as a z-score < -1.64 SD) of 3.8 (95% CI, 1.3-10.9) and of 4.3 (95% CI, 1.2-15.0), respectively. The results for PM10 were similar to those for NOx. CONCLUSIONS Exposure to traffic-related air pollution in infancy is negatively associated with FEV1 at age 16 years, leading to increased risk of clinically important deficits.

Lung function at 6 and 18 months after preterm birth in relation to severity of bronchopulmonary dysplasia

Many preterm infants with bronchopulmonary dysplasia (BPD) demonstrate impaired lung function and respiratory symptoms during infancy. The relationships between initial BPD severity, lung function and respiratory morbidity are not fully understood. We aimed to investigate the association between BPD severity and subsequent lung function and whether lung function impairment is related to respiratory morbidity.

Lung Function at 8 and 16 Years After Moderate-to-Late Preterm Birth: A Prospective Cohort Study

BACKGROUND AND OBJECTIVE: Knowledge regarding lung function after moderately preterm birth is limited. We therefore investigated lung function at early school age and adolescence among children born moderately preterm. METHODS: Data were used from the Swedish prospective birth cohort BAMSE (Swedish abbreviation for Children, Allergy, Milieu, Stockholm, Epidemiology study; N = 4089), with a 4.8% prevalence of moderate to late preterm birth defined as a gestational age of 32 to 36 weeks. Participants underwent spirometry at ages 8 and 16 years, and impulse oscillometry additionally at age 16 years. In total, 2621 children (149 preterm and 2472 term) provided lung function data. RESULTS: At age 8 years, adjusted forced expiratory volume in 1 second was lower in preterm female subjects (–64 mL [95% confidence interval (CI): –118 to –10]) compared with term female subjects but not in preterm male subjects. At age 16 years, both genders in the preterm group demonstrated lower forced expiratory volume in 1 second (female subjects: –116 mL [95% CI: –212 to –20]; male subjects: –177 mL [95% CI: –329 to –25]) compared with the term group. For the preterm group, impulse oscillometry demonstrated higher adjusted resistance at 5 Hz (female subjects: 31.3 Pa·L–1·s−1 [95% CI: 6.3 to 56.3]; male subjects: 34.9 Pa·L–1·s−1 [95% CI: 12.0 to 57.7]) and frequency dependence of resistance (resistance at 5 and 20 Hz) for male subjects (20.9 Pa·L–1·s−1 [95% CI: 9.8 to 31.9]) compared with the term group. CONCLUSIONS: Measures of airway function assessed in adolescence were reduced in children born moderate to late preterm, and no catch-up in lung function between ages 8 and 16 years was observed.

Asthma phenotypes and lung function up to 16 years of age-the BAMSE cohort.

Asthma is a disease affecting many locations throughout the airway. Most studies have used spirometry as the primary assessment of airway obstruction, a method that may be less sensitive in regard to peripheral airway obstruction. The aim of this study was to elucidate the associations between asthma phenotypes based on age of onset and duration of symptoms, and (i) spirometry and (ii) small airway involvement measured by impulse oscillometry (IOS) in adolescence.

Asthma in children exposed to nitrogen dioxide in ice arenas

Very high concentrations of nitrogen dioxide (NO2) have been measured in arenas using combustion engine-powered resurfacing machines. This study was performed to compare the occurrence of asthma in children playing ice hockey in arenas using propane-powered machines and in children attending arenas using electric machines. Children regularly playing hockey in the arenas (nine propane, six electric) were sent a questionnaire, including questions on allergic disease and risk factors. Measurements of NO2 were performed with passive diffusion samplers during 3 consecutive days. The mean NO2 concentration in the propane arenas was 276 µg·m−3 (range 28–1015 µg·m−3) and 11 µg·m−3 (2–30) in the electric arenas. Questionnaires were answered by 1,536 children (78%), with an overall prevalence of asthma of 16%. The odds ratio (OR) for asthma was 0.9 (95% confidence interval (CI) 0.7–1.2) comparing propane arenas to electric. However, children in propane arenas with higher than median concentration of NO2 reported more wheezing (OR 1.4, 95% CI 1.0–1.9) and nasal symptoms (OR 1.7, 95% CI 1.3–2.3) than children in propane arenas with lower concentrations. In conclusion, children playing ice hockey in indoor arenas have a high prevalence of asthma, but it appears unlikely that increased exposure to combustion products, including nitrogen dioxide, is a major contributor to this excess risk.

Infant wheeze, comorbidities and school age asthma

Factors associated with early onset of wheeze have been described, but there is limited knowledge on which of these infant wheezers who will have developed asthma in school age. The aim was to identify clinical risk factors for asthma in the 8‐yr‐old children that wheezed during infancy in a population‐based setting.

Body mass index status and peripheral airway obstruction in school-age children: a population-based cohort study

Background Few large prospective studies have investigated the impact of body mass index (BMI) on lung function during childhood. Methods Using data collected between 2002 and 2013, we analysed associations between BMI status and lung function (assessed by spirometry) from 8 to 16 years, as well as cross-sectional associations with small airway function (impulse oscillometry) at 16 years in the BAMSE cohort (n=2889). At 16 years, cross-sectional associations with local and systemic inflammation were investigated by analysing FENO, blood eosinophils and neutrophils. Results Overweight and obesity at 8 years were associated with higher FVC, but lower FEV1/FVC ratio at 8 and 16 years. In boys, but not girls, obesity at 8 years was associated with a further reduction in FEV1/FVC between 8 and 16 years. In cross-sectional analyses, overweight and obesity were associated with higher frequency dependence of resistance (R5–20) and larger area under the reactance curve (AX0.5) at 16 years. Increased blood neutrophil counts were seen in overweight and obese girls, but not in boys. No association was found between BMI status and FENO. Persistent, but not transient, overweight/obesity between 8 and 16 years was associated with higher R5–20 and AX0.5 and lower FEV1/FVC (−2.8% (95% CI −4.1 to −1.2) in girls and −2.7% (95% CI −4.4 to −1.1) in boys) at 16 years, compared with persistent normal weight. Conclusion In childhood and adolescence, overweight and obesity, particularly persistent overweight, were associated with evidence of airway obstruction, including the small airways.

Early life determinants of lung function change from childhood to adolescence

RATIONALE Little is known about how perinatal and childhood factors influence lung function change between childhood and adolescence. OBJECTIVES To investigate possible early life predictors of change in FEV1 between age 8 and 16 years. In addition, to investigate possible predictors of having persistently low lung function (FEV1 <25th percentiles both at age 8 and 16) up to adolescence. METHODS The BAMSE birth cohort study collected data throughout childhood on environmental factors, individual characteristics, and spirometric measures at 8 and 16 years (n = 1425). Associations between early life predictors (n = 31) and FEV1 increase between 8 and 16 years were assessed with linear regression. Predictors of having persistently low lung function were examined. RESULTS Few factors were consistently associated with altered lung function growth, although low birth weight, asthma heredity (paternal), secondhand smoke in infancy, and season of birth had a significant impact (p-value ≤0.01). The majority of subjects stayed however within the same category of lung function between ages 8 and 16 years (in total 821/1425 = 58%). Predictors associated with having persistently low lung function were gestational age, secondhand smoke (at 2 and 8 years of age), and factors related to lower respiratory tract infections in infancy. CONCLUSIONS In summary, rather few exposures in childhood were identified to have a significant impact on lung function growth between childhood and adolescence. Our data support previous study findings indicating that lung function development is influenced by factors before birth and in infancy, including second hand tobacco smoke.

Lung function after extremely preterm birth—A population‐based cohort study (EXPRESS)

Follow‐up studies of children and young adults born very‐to‐moderately preterm show persistent and significant lung function deficits. The aim of the study was to determine lung function and airway mechanics in school‐aged children born in 2004 to 2007 and extremely preterm (after 22‐26 weeks of gestation).