Chronic Bronchitis in Children and Adults: Definitions, Pathophysiology, Prevalence, Risk Factors, and Consequences.

The complex nature of chronic bronchitis (CB) and changing definitions have contributed to challenges in understanding its aetiology and burden. In children, CB is characterised by persistent airway inflammation often linked to bacterial infections and is therefore termed "protracted bacterial bronchitis" (PBB). Longitudinal studies suggest that CB in childhood persists into adulthood in a subgroup. It can also be associated with future chronic respiratory diseases including asthma, bronchiectasis, and chronic obstructive pulmonary disease (COPD). Adult CB is traditionally associated with smoking, occupational exposures, and lower socioeconomic status. The interplay between risk factors, childhood CB, adult CB, and other chronic respiratory diseases is intricate, requiring comprehensive longitudinal studies for a clearer understanding of the natural history of CB across the lifespan. Such longitudinal studies have been scarce to date given the logistic challenges of maintaining them over time. In this review, we summarise current evidence on the evolution of the definitions, pathophysiology, risk factors, and consequences of childhood and adulthood chronic bronchitis.

Associations of early life and childhood risk factors with obstructive sleep apnoea in middle-age.

BACKGROUND AND OBJECTIVE: Early-life risk factors for obstructive sleep apnoea (OSA) are poorly described, yet this knowledge may be critical to inform preventive strategies. We conducted the first study to investigate the association between early-life risk factors and OSA in middle-aged adults. METHODS: Data were from population-based Tasmanian Longitudinal Health Study cohort (n = 3550) followed from 1st to 6th decades of life. Potentially relevant childhood exposures were available from a parent-completed survey at age 7-years, along with previously characterized risk factor profiles. Information on the primary outcome, probable OSA (based on a STOP-Bang questionnaire cut-off ≥5), were collected when participants were 53 years old. Associations were examined using logistic regression adjusting for potential confounders. Analyses were repeated using the Berlin questionnaire. RESULTS: Maternal asthma (OR = 1.5; 95% CI 1.1-2.0), maternal smoking (OR = 1.2; 1.05, 1.5), childhood pleurisy/pneumonia (OR = 1.3; 1.04, 1.7) and frequent bronchitis (OR = 1.2; 1.01, 1.5) were associated with probable OSA. The risk-factor profiles of 'parental smoking' and 'frequent asthma and bronchitis' were also associated with probable OSA (OR = 1.3; 1.01, 1.6 and OR = 1.3; 1.01-1.9, respectively). Similar associations were found for Berlin questionnaire-defined OSA. CONCLUSIONS: We found novel temporal associations of maternal asthma, parental smoking and frequent lower respiratory tract infections before the age of 7 years with adult OSA. While determination of their pathophysiological and any causal pathways require further research, these may be useful to flag the risk of OSA within clinical practice and create awareness and vigilance among at-risk groups.

Association of novel adult cough subclasses with clinical characteristics and lung function across six decades of life in a prospective, community-based cohort in Australia: an analysis of the Tasmanian Longitudinal Health Study (TAHS).

BACKGROUND: Cough is a common yet heterogeneous condition. Little is known about the characteristics and course of cough in general populations. We aimed to investigate cough subclasses, their characteristics from childhood across six decades of life, and potential treatable traits in a community-based cohort. METHODS: For our analysis of the Tasmanian Longitudinal Health Study (TAHS), a prospective, community-based cohort study that began on Feb 23, 1968, and has so far followed up participants in Tasmania, Australia, at intervals of 10 years from a mean age of 7 years to a mean age of 53 years, we used data collected as part of the TAHS to distinguish cough subclasses among current coughers at age 53 years. For this analysis, participants who answered Yes to at least one cough-related question via self-report questionnaire were defined as current coughers and included in a latent class analysis of cough symptoms; participants who answered No to all nine cough-related questions were defined as non-coughers and excluded from this analysis. Two groups of longitudinal features were assessed from age 7 years to age 53 years: previously established longitudinal trajectories of FEV1, forced vital capacity [FVC], FEV1/FVC ratio, asthma, and allergies-identified via group-based trajectory analysis or latent class analysis-and symptoms at different timepoints, including asthma, current productive cough, ever chronic productive cough, current smoking, and second-hand smoking. FINDINGS: Of 8583 participants included at baseline in the TAHS, 6128 (71·4%) were traced and invited to participate in a follow-up between Sept 3, 2012, and Nov 8, 2016; 3609 (58·9%) of these 6128 returned the cough questionnaire. The mean age of participants in this analysis was 53 years (SD 1·0). 2213 (61·3%) of 3609 participants were defined as current coughers and 1396 (38·7%) were categorised as non-coughers and excluded from the latent class analysis. 1148 (51·9%) of 2213 participants in this analysis were female and 1065 (48·1%) were male. Six distinct cough subclasses were identified: 206 (9·3%) of 2213 participants had minimal cough, 1189 (53·7%) had cough with colds only, 305 (13·8%) had cough with allergies, 213 (9·6%) had intermittent productive cough, 147 (6·6%) had chronic dry cough, and 153 (6·9%) had chronic productive cough. Compared with people with minimal cough, and in contrast to other cough subclasses, people in the chronic productive cough and intermittent productive cough subclasses had worse lung function trajectories (FEV1 persistent low trajectory 2·9%, 6·4%, and 16·1%; p=0·0011, p<0·0001; FEV1/FVC early low-rapid decline trajectory 2·9%, 12·1%, and 13·0%; p=0·012, p=0·0007) and a higher prevalence of cough (age 53 years 0·0%, 32·4% [26·1-38·7], and 50·3% [42·5-58·2]) and asthma (age 53 years 6·3% [3·7-10·6], 26·9% [21·3-33·3], and 41·7% [24·1-49·7]) from age 7 years to age 53 years. INTERPRETATION: We identified potential treatable traits for six cough subclasses (eg, asthma, allergies, and active and passive smoking for productive cough). The required management of productive cough in primary care (eg, routine spirometry) might differ from that of dry cough if our findings are supported by other studies. Future population-based studies could apply our framework to address the heterogeneity and complexity of cough in the community. FUNDING: The National Health and Medical Research Council of Australia, The University of Melbourne, Clifford Craig Medical Research Trust of Tasmania, Victorian Asthma Foundation, Queensland Asthma Foundation, Tasmanian Asthma Foundation, The Royal Hobart Hospital Research Foundation, the Helen MacPherson Smith Trust, GlaxoSmithKline, and the China Scholarship Council.

Early life exposures contributing to accelerated lung function decline in adulthood - a follow-up study of 11,000 adults from the general population.

Background: We aimed to assess whether exposure to risk factors in early life from conception to puberty continue to contribute to lung function decline later in life by using a pooled cohort comprising approx. 11,000 adults followed for more than 20 years and with up to three lung function measurements. Methods: Participants (20-68 years) in the ECRHS and NFBC1966 cohort studies followed in the periods 1991-2013 and 1997-2013, respectively, were included. Mean annual decline in maximum forced expired volume in 1 s (FEV1) and forced vital capacity (FVC) were main outcomes. Associations between early life risk factors and change in lung function were estimated using mixed effects linear models adjusted for sex, age, FEV1, FVC and height at baseline, accounting for personal smoking. Findings: Decline in lung function was accelerated in participants with mothers that smoked during pregnancy (FEV1 2.3 ml/year; 95% CI: 0.7, 3.8) (FVC 2.2 ml/year; 0.2, 4.2), with asthmatic mothers (FEV1 2.6 ml/year; 0.9, 4.4) (FEV1/FVC 0.04 per year; 0.04, 0.7) and asthmatic fathers (FVC 2.7 ml/year; 0.5, 5.0), and in women with early menarche (FVC 2.4 ml/year; 0.4, 4.4). Personal smoking of 10 pack-years contributed to a decline of 2.1 ml/year for FEV1 (1.8, 2.4) and 1.7 ml/year for FVC (1.3, 2.1). Severe respiratory infections in early childhood were associated with accelerated decline among ever-smokers. No effect-modification by personal smoking, asthma symptoms, sex or cohort was found. Interpretation: Mothers' smoking during pregnancy, parental asthma and early menarche may contribute to a decline of FEV1 and FVC later in life comparable to smoking 10 pack-years. Funding: European Union's Horizon 2020; Research Council of Norway; Academy of Finland; University Hospital Oulu; European Regional Development Fund; Spanish Ministry of Science and Innovation; Generalitat de Catalunya.

The longitudinal association between physical activity, strength and fitness, and lung function: A UK Biobank cohort study.

BACKGROUND: While physical activity is hypothesized to slow lung-function decline, the evidence is limited at a population level. This study investigated the longitudinal association between physical activity and related measures (grip strength, cardiovascular fitness) and lung function decline. METHODS: 20,111 UK Biobank cohort participants with lung function measures at baseline (2006-2010) and follow-up (2012-2014) were included. Physical activity (International Physical Activity Questionnaire: low, moderate, high categories), grip strength (dynamometer) and cardiovascular fitness (subsample, submaximal stationary bicycle) data were collected. Linear regression was utilized to assess the effect on follow-up FEV1, FVC, FEV1/FVC ratio (as decline in ml/yr and as z-scores) adjusting for baseline lung function and confounders. RESULTS: After 6.3 years mean follow-up, the decline in mean FEV1 and FVC was 30 ml/year and 38 ml/year respectively (n = 20,111). Consistent low physical activity (across baseline and follow-up) was associated with accelerated decline in FEV1 z-score (-0.119, 95 % Confidence Interval (CI) -0.168, -0.071, n = 16,900) and FVC z-score (-0.133, 95%CI -0.178, -0.088, n = 16,832). Accelerated decline in FEV1 z-scores was observed with decreasing baseline grip strength (-0.029, -95%CI -0.034, -0.024, n = 19,903), and with less strong evidence, decreasing fitness (-0.024, 95%CI -0.070, 0.022, n = 3048). CONCLUSION: This is the largest ever study to date to identify that lower physical activity, grip strength, and potentially cardiovascular fitness over time is associated with accelerated lung function decline. Although the effect sizes appear modest, such changes at population levels can have a substantial overall impact. This study provides evidence for adding 'lung health benefits' to the current physical activity guidelines.

Longitudinal risk factors for obstructive sleep apnea: A systematic review.

Despite substantial disease burden, existing evidence on the risk factors for obstructive sleep apnea (OSA) have been derived primarily from cross-sectional studies without determining temporality. Therefore, we aimed to systematically synthesize the literature on longitudinal risk factors for sleep study-assessed OSA and questionnaire-assessed probable OSA from cohort studies in the general adult population settings. We systematically searched Embase and Medline (on OVID) databases. Eleven studies met the inclusion criteria. Meta-analyses were not conducted due to methodological heterogeneity of exposure and outcome measurements. There was consistent evidence that weight gain was associated with incident (n = 2) and greater severity (n = 2) of OSA. One study each observed an association of higher baseline body-mass index, male sex, asthma, a specific genetic polymorphism in rs12415421, and insulin resistance/hyperglycemia, with incident OSA. Long-term exposure to ambient air pollution (NO2, n = 1) was associated with OSA, and menopausal transitions (n = 1) with higher apnea-hypopnea index. There were no eligible studies on long-term smoking or alcohol use. In conclusion, approximately 10% increase in weight, especially in males, might alert clinicians to consider potential or worsening OSA. Large, well-designed longitudinal studies are needed to consolidate knowledge on other associations with OSA development, especially on potentially modifiable risk factors.

Cohort profile: the multigeneration Respiratory Health in Northern Europe, Spain and Australia (RHINESSA) cohort.

PURPOSE: The Respiratory Health in Northern Europe, Spain and Australia (RHINESSA) cohort was established to (1) investigate how exposures before conception and in previous generations influence health and disease, particularly allergies and respiratory health, (2) identify susceptible time windows and (3) explore underlying mechanisms. The ultimate aim is to facilitate efficient intervention strategies targeting multiple generations. PARTICIPANTS: RHINESSA includes study participants of multiple generations from ten study centres in Norway (1), Denmark (1), Sweden (3), Iceland (1), Estonia (1), Spain (2) and Australia (1). The RHINESSA core cohort, adult offspring generation 3 (G3), was first investigated in 2014-17 in a questionnaire study (N=8818, age 18-53 years) and a clinical study (subsample, n=1405). Their G2 parents participated in the population-based cohorts, European Community Respiratory Heath Survey and Respiratory Health In Northern Europe, followed since the early 1990s when they were 20-44 years old, at 8-10 years intervals. Study protocols are harmonised across generations. FINDINGS TO DATE: Collected data include spirometry, skin prick tests, exhaled nitric oxide, anthropometrics, bioimpedance, blood pressure; questionnaire/interview data on respiratory/general/reproductive health, indoor/outdoor environment, smoking, occupation, general characteristics and lifestyle; biobanked blood, urine, gingival fluid, skin swabs; measured specific and total IgE, DNA methylation, sex hormones and oral microbiome. Research results suggest that parental environment years before conception, in particular, father's exposures such as smoking and overweight, may be of key importance for asthma and lung function, and that there is an important susceptibility window in male prepuberty. Statistical analyses developed to approach causal inference suggest that these associations may be causal. DNA methylation studies suggest a mechanism for transfer of father's exposures to offspring health and disease through impact on offspring DNA methylation. FUTURE PLANS: Follow-up is planned at 5-8 years intervals, first in 2021-2023. Linkage with health registries contributes to follow-up of the cohort.

Association between very to moderate preterm births, lung function deficits, and COPD at age 53 years: analysis of a prospective cohort study.

BACKGROUND: Prematurity has been linked to reduced lung function up to age 33 years, but its long-term effects on lung function and chronic obstructive pulmonary disease (COPD) are unknown. To address this question, we investigated associations between prematurity, lung function, and COPD in the sixth decade of life using data from the Tasmanian Longitudinal Health Study (TAHS). METHODS: Data were analysed from 1445 participants in the TAHS. Lung function was measured at 53 years of age. Gestational ages were very preterm (28 weeks to <32 weeks), moderate preterm (32 weeks to <34 weeks), late preterm (34 weeks to <37 weeks) and term (≥37 weeks). Linear and logistic regression models were fitted to investigate associations of prematurity with lung function measures (FEV1, forced vital capacity [FVC], FEV1/FVC ratio, forced expiratory flow at 25-75% of FVC [FEF25-75%], diffusing capacity for carbon monoxide [DLCO]) and COPD (post-bronchodilator FEV1/FVC less than the lower limit of normal), adjusting for sex, age, height, parental smoking during pregnancy, number of older siblings, maternal age at birth, and childhood socioeconomic status. Interactions with smoking and asthma were also investigated. RESULTS: Of 3565 individuals with available data on gestational age from the TAHS cohort, 1445 (41%) participants were included in this study, 740 (51%) of whom were female. Compared with term birth, very to moderate preterm birth was significantly associated with an increased risk of COPD at age 53 years (odds ratio 2·9 [95% CI 1·1-7·7]). Very-to-moderate preterm birth was also associated with lower post-bronchodilator FEV1/FVC ratio (beta-coefficient -2·9% [95% CI -4·9 to -0·81]), FEV1 (-190 mL [-339 to -40]), DLCO (-0·55 mmol/min/kPa [-0·97 to -0·13]), and FEF25-75% (-339 mL/s [-664 to -14]). The association between very-to-moderate preterm birth and FEV1/FVC ratio was only significant among smokers (pinteraction=0·0082). Similar findings were observed for moderate preterm birth when analysed as a separate group. Compared with term birth, late preterm birth was not associated with lower FEV1/FVC ratio or COPD. INTERPRETATION: This is the first study to investigate the effect of prematurity on lung function into middle-age. Data show that very-to-moderate prematurity is associated with obstructive lung function deficits including COPD well into the sixth decade of life and that this effect is compounded by personal smoking. FUNDING: National Health and Medical Research Council (NHMRC) of Australia, European Union's Horizon 2020, The University of Melbourne, Clifford Craig Medical Research Trust of Tasmania, The Victorian, Queensland & Tasmanian Asthma Foundations, The Royal Hobart Hospital, Helen MacPherson Smith Trust, and GlaxoSmithKline.

Risk factors for chronic cough in adults: A systematic review and meta-analysis.

Despite the challenges of diagnosing and managing adult patients with chronic cough, a systematic synthesis of evidence on aetiological risk factor is lacking. We systematically searched PubMed and EMBASE to synthesize the current evidence for longitudinal associations between a wide range of risk factors and chronic cough in the general adult population, following the meta-analysis of observational studies in epidemiology (MOOSE) guidelines. The Newcastle-Ottawa scale was used to assess the quality of the included studies. Fixed-effect meta-analysis was conducted where appropriate. Of 26 eligible articles, 16 domains of risk factors were assessed. There was consistent evidence that asthma (pooled adjusted OR [aOR] = 3.01; 95% CI: 2.33-3.70; I2  = 0%; number of articles [N] = 3) and low education levels/socioeconomic status (SES) (pooled aOR = 1.46; 95% CI: 1.20-1.72; I2  = 0%; N = 3) were associated with an increased risk of chronic cough after adjusting for smoking and other confounders. While continuous smoking was associated with chronic cough (aOR = 1.81; 95% CI: 1.36-2.26; I2  = 57%; N = 3), there was too little evidence to draw conclusions for occupational exposures, outdoor air pollution, early-life exposures, diet, snoring and other chronic conditions, including obesity, chronic obstructive pulmonary disease, gastro-oesophageal reflux disease and chronic pain. Asthma, persistent smoking and lower education/SES were associated with an increased risk of chronic cough. Longitudinal associations between other factors frequently mentioned empirically (i.e., occupational exposures, air pollution and chronic respiratory conditions) need further investigation, ideally with objective and standardized measurement.

The relationship of early-life household air pollution with childhood asthma and lung function.

The increase in childhood asthma over the past few decades has made it an important public health issue. Poor lung function growth associated with some phenotypes of asthma compounds its long-term impact on the individual. Exposure to early-life household risk factors is believed to be linked with respiratory health while infants' lungs are still developing. This review summarises epidemiological studies and mechanistic evidence focusing on the detrimental effects of early-life household air exposures on the respiratory health of children, in particular effects on asthma and lung function. Many early-life household air exposures, including tobacco smoke, gases from heating and cooking, mould/dampness and cleaning products are associated with childhood asthma development and lung function growth. These exposures may alter structural and mechanical characteristics of infants' lungs and contribute to deficits in later life. In addition, some risk factors, including tobacco smoke and cleaning products, can transmit effects across generations to increase the risk of asthma in subsequent generations. This review supports the hypothesis that risks of asthma and accelerated lung ageing are established in early life. The timing of exposure may be critical in the pathogenesis of respiratory diseases, in terms of future risk of asthma and reduced lung function in adults.

Ten-year prediction model for post-bronchodilator airflow obstruction and early detection of COPD: development and validation in two middle-aged population-based cohorts.

BACKGROUND: Classifying individuals at high chronic obstructive pulmonary disease (COPD)-risk creates opportunities for early COPD detection and active intervention. OBJECTIVE: To develop and validate a statistical model to predict 10-year probabilities of COPD defined by post-bronchodilator airflow obstruction (post-BD-AO; forced expiratory volume in 1 s/forced vital capacity<5th percentile). SETTING: General Caucasian populations from Australia and Europe, 10 and 27 centres, respectively. PARTICIPANTS: For the development cohort, questionnaire data on respiratory symptoms, smoking, asthma, occupation and participant sex were from the Tasmanian Longitudinal Health Study (TAHS) participants at age 41-45 years (n=5729) who did not have self-reported COPD/emphysema at baseline but had post-BD spirometry and smoking status at age 51-55 years (n=2407). The validation cohort comprised participants from the European Community Respiratory Health Survey (ECRHS) II and III (n=5970), restricted to those of age 40-49 and 50-59 with complete questionnaire and spirometry/smoking data, respectively (n=1407). STATISTICAL METHOD: Risk-prediction models were developed using randomForest then externally validated. RESULTS: Area under the receiver operating characteristic curve (AUCROC) of the final model was 80.8% (95% CI 80.0% to 81.6%), sensitivity 80.3% (77.7% to 82.9%), specificity 69.1% (68.7% to 69.5%), positive predictive value (PPV) 11.1% (10.3% to 11.9%) and negative predictive value (NPV) 98.7% (98.5% to 98.9%). The external validation was fair (AUCROC 75.6%), with the PPV increasing to 17.9% and NPV still 97.5% for adults aged 40-49 years with ≥1 respiratory symptom. To illustrate the model output using hypothetical case scenarios, a 43-year-old female unskilled worker who smoked 20 cigarettes/day for 30 years had a 27% predicted probability for post-BD-AO at age 53 if she continued to smoke. The predicted risk was 42% if she had coexistent active asthma, but only 4.5% if she had quit after age 43. CONCLUSION: This novel and validated risk-prediction model could identify adults aged in their 40s at high 10-year COPD-risk in the general population with potential to facilitate active monitoring/intervention in predicted 'COPD cases' at a much earlier age.

Is asthma associated with COVID-19 infection? A UK Biobank analysis.

BACKGROUND: The relationship between asthma and coronavirus disease 2019 (COVID-19) risk is not clear and may be influenced by level of airway obstruction, asthma medication and known COVID-19 risk factors. We aimed to investigate COVID-19 risk in people with asthma. METHODS: We used UK Biobank data from all participants tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (n=107 412; 17 979 test positive). Questions at baseline defined ever asthma and asthma medications. Baseline forced expiratory volume in 1 s (FEV1) was categorised into quartiles. Logistic regression modelled relationships between asthma, and asthma categories (age at onset, medications, FEV1 quartiles), and risk of SARS-CoV-2 positive test. We investigated modification by sex, ethnic group, smoking and body mass index. RESULTS: There was a reduced risk of a positive test associated with early-onset asthma (<13 years) (OR 0.91, 95% CI 0.84-0.99). This was found for participants with early-onset asthma who were male (OR 0.87, 95% CI 0.78-0.98), nonsmokers (OR 0.87, 95% CI 0.78-0.98), overweight/obese (OR 0.85, 95% CI 0.77-0.93) and non-Black (OR 0.90, 95% CI 0.82-0.98). There was increased risk amongst early-onset individuals with asthma in the highest compared to lowest quartile of lung function (1.44, 1.05-1.72). CONCLUSION: Amongst male, nonsmoking, overweight/obese and non-Black participants, having early-onset asthma was associated with lower risk of a SARS-CoV-2 positive test. We found no evidence of a protective effect from asthma medication. Individuals with early-onset asthma of normal weight and with better lung function may have lifestyle differences placing them at higher risk. Further research is needed to elucidate the contribution of asthma pathophysiology and different health-related behaviour, across population groups, to the observed risks.

Childhood lung function as a determinant of menopause-dependent lung function decline.

RATIONALE: The naturally occurring age-dependent decline in lung function accelerates after menopause, likely due to the change of the endocrine balance. Although increasing evidence shows suboptimal lung health in early life can increase adult  susceptibility to insults, the potential effect of poor childhood lung function on menopause-dependent lung function decline has not yet been investigated. OBJECTIVES: To study whether menopause-dependent lung function decline, assessed as forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), is determined by childhood lung function. METHODS: The Tasmanian Longitudinal Health Study, a cohort born in 1961, underwent spirometry at age seven.  At ages 45 and 50 serum samples, spirometry and questionnaire data were collected (N = 506). We measured follicle stimulating and luteinizing hormones to determine menopausal status using latent profile analysis. The menopause-dependent lung function decline was investigated using linear mixed models, adjusted for anthropometrics, occupational level, smoking, asthma, asthma medication and study year, for the whole study population and stratified by tertiles of childhood lung function. MEASUREMENTS AND MAIN RESULTS: The overall menopause-dependent lung function decline was 19.3 mL/y (95%CI 2.2 to 36.3) for FVC and 9.1 mL/y (-2.8 to 21.0) for FEV1. This was most pronounced (pinteraction=0.03) among women within the lowest tertile of childhood lung function [FVC 22.2 mL/y (1.1 to 43.4); FEV1 13.9 mL/y (-1.5 to 29.4)]. CONCLUSIONS: Lung function declines especially rapidly in postmenopausal women who had poor low lung function in childhood. This provides novel insights into respiratory health during reproductive aging and emphasizes the need for holistic public health strategies covering the whole lifespan.

Lung function trajectory and biomarkers in the Tasmanian Longitudinal Health Study.

BACKGROUND AND OBJECTIVE: Different lung function trajectories through life can lead to COPD in adulthood. This study investigated whether circulating levels of biomarkers can differentiate those with accelerated (AD) from normal decline (ND) trajectories. METHODS: The Tasmanian Longitudinal Health Study (TAHS) is a general population study that measured spirometry and followed up participants from ages 7 to 53 years. Based on their forced expiratory volume in 1 s (FEV1) trajectories from age 7 to 53 years, this analysis included those with COPD at age 53 years (60 with AD and 94 with ND) and controls (n=720) defined as never-smokers with an average FEV1 trajectory. Circulating levels of selected biomarkers determined at 53 and 45 years of age were compared between trajectories. RESULTS: Results showed that CC16 levels (an anti-inflammatory protein) were lower and C-reactive protein (CRP) (a pro-inflammatory marker) higher in the AD than in the ND trajectory. Higher CC16 levels were associated with a decreased risk of belonging to the AD trajectory (OR=0.79 (0.63-0.98) per unit increase) relative to ND trajectory. Higher CRP levels were associated with an increased risk of belonging to the AD trajectory (OR=1.07, 95% CI: 1.00-1.13, per unit increase). Levels of CC16 (area under the curve (AUC)=0.69, 95% CI: 0.56-0.81, p=0.002), CRP (AUC=0.63, 95% CI: 0.53-0.72, p=0.01) and the combination of both (AUC=0.72, 95% CI: 0.60-0.83, p<0.001) were able to discriminate between the AD and ND trajectories. Other quantified biomarkers (interleukin (IL)-4, IL-5, IL-6, IL-10 and tumour necrosis factor-α (TNF-α)) were not significantly different between AD, ND and controls. CONCLUSIONS: Circulating levels of CRP and CC16 measured in late adulthood identify different lung function trajectories (AD versus ND) leading to COPD at age 53 years.

Predictors of lung function trajectories in population-based studies: A systematic review.

Despite the growing body of evidence on lung function trajectories over the life course and their risk factors, the literature has not been systematically synthesized. Publications related to lung function trajectories were identified from PubMed, EMBASE and CINAHL databases. Two authors independently identified publications for inclusion according to predefined selection criteria. Studies that modelled lung function trajectories and reported associated exposures were included. Meta-analyses could not be conducted due to heterogeneity in the exposures and methods used to model lung function trajectories. Nine publications were eligible for inclusion of which four used group-based trajectory modelling to model lung function trajectories, while five used latent profile analysis. Studies with repeated lung function measurements over the life course identified more trajectories than others. Only one study spanning from childhood to middle age reported catch-up trajectory. The following childhood risk factors for subnormal lung function trajectories were observed in at least across two studies: low birth weight, early wheezing, asthma, allergic sensitization, eczema, allergic rhinitis, lower respiratory tract infections, family history of asthma and second-hand smoke exposure. Adult active asthma and personal cigarette smoking were observed to be associated with accelerated decline lung trajectories. Our review identified 10 risk factors associated with the growth, catch-up, reduced plateau and decline trajectories of lung function. Intervention directed at childhood asthma and infections, and tobacco smoke exposure at all ages would help promote lung health and prevent subnormal lung function trajectories.

Exposure to household air pollution over 10†years is related to asthma and lung function decline.

INTRODUCTION: We investigated if long-term household air pollution (HAP) is associated with asthma and lung function decline in middle-aged adults, and whether these associations were modified by glutathione S-transferase (GST) gene variants, ventilation and atopy. MATERIALS AND METHODS: Prospective data on HAP (heating, cooking, mould and smoking) and asthma were collected in the Tasmanian Longitudinal Health Study (TAHS) at mean ages 43 and 53 years (n=3314). Subsamples had data on lung function (n=897) and GST gene polymorphisms (n=928). Latent class analysis was used to characterise longitudinal patterns of exposure. Regression models assessed associations and interactions. RESULTS: We identified seven longitudinal HAP profiles. Of these, three were associated with persistent asthma, greater lung function decline and % reversibility by age 53 years compared with the "Least exposed" reference profile for those who used reverse-cycle air conditioning, electric cooking and no smoking. The "All gas" (OR 2.64, 95% CI 1.22-5.70), "Wood heating/smoking" (OR 2.71, 95% CI 1.21-6.05) and "Wood heating/gas cooking" (OR 2.60, 95% CI 1.11-6.11) profiles were associated with persistent asthma, as well as greater lung function decline and % reversibility. Participants with the GSTP1 Ile/Ile genotype were at a higher risk of asthma or greater lung function decline when exposed compared with other genotypes. Exhaust fan use and opening windows frequently may reduce the adverse effects of HAP produced by combustion heating and cooking on current asthma, presumably through increasing ventilation. CONCLUSIONS: Exposures to wood heating, gas cooking and heating, and tobacco smoke over 10 years increased the risks of persistent asthma, lung function decline and % reversibility, with evidence of interaction by GST genes and ventilation.

Parental occupational exposure pre- and post-conception and development of asthma in offspring.

BACKGROUND: While direct effects of occupational exposures on an individual's respiratory health are evident, a new paradigm is emerging on the possible effects of pre-conception occupational exposure on respiratory health in offspring. We aimed to study the association between parental occupational exposure starting before conception and asthma in their offspring (at 0-15 years of age). METHODS: We studied 3985 offspring participating in the Respiratory Health in Northern Europe, Spain and Australia (RHINESSA) generation study. Their mothers or fathers (n = 2931) previously participated in the European Community Respiratory Health Survey (ECRHS). Information was obtained from questionnaires on parental job history pre- and post-conception which was linked to an asthma-specific job-exposure matrix (JEM). We assessed the association between parental occupational exposure and offspring asthma, applying logistic regression models, clustered by family and adjusted for study centre, offspring sex, parental characteristics (age, asthma onset, place of upbringing, smoking) and grandparents' level of education. RESULTS: Parental occupational exposure to microorganisms, pesticides, allergens or reactive chemicals pre-conception or both pre- and post-conception was not related to offspring asthma; in general, subgroup analyses confirmed this result. However, maternal exposure both pre- and post-conception to allergens and reactive chemicals was associated with increased odds for early-onset asthma in offspring (0-3 years of age); odds ratio 1.70 (95% CI: 1.02-2.84) and 1.65 (95% CI: 0.98-2.77), respectively. CONCLUSIONS: This study did not find evidence that parental occupational exposure, defined by an asthma JEM before conception only or during pre- and post-conception vs non-exposed, was associated with offspring asthma.

Association of early life and acute pollen exposure with lung function and exhaled nitric oxide (FeNO). A prospective study up to adolescence in the GINIplus and LISA cohort.

BACKGROUND: Pollen exposure has both acute and chronic detrimental effects on allergic asthma, but little is known about its wider effects on respiratory health. This is increasingly important knowledge as ambient pollen levels are changing with the changing global climate. OBJECTIVE: To assess associations of pollen exposure with lung function and fractional exhaled nitric oxide (FeNO) at age 15 in two prospective German birth cohorts, GINIplus and LISA. METHODS: Background city-specific pollen exposure was measured in infancy (during the first three months of life), and contemporary (on the day of and 7 days prior to lung function measurement). Greenness levels within circular buffers (100-3000 m) around the birth and 15-year home addresses were calculated using the satellite-derived Normalized Difference Vegetation Index. Regression models were used to assess the associations of grass and birch pollen with lung function and FeNO, and the modifying effects of residential greenness were explored. RESULTS: Cumulative early life exposure to grass pollen was associated with reduced lung function in adolescence (FEV1: -4.9 mL 95%CI: -9.2, -0.6 and FVC: -5.2 mL 95%CI: -9.8, -0.5 per doubling of pollen count). Acute grass pollen exposure was associated with increased airway inflammation in all children, with higher FeNO increases in children living in green areas. In contrast acute birch pollen exposure was associated with reduced lung function only in children sensitised to birch allergens. CONCLUSION: This study provides suggestive evidence that early pollen exposure has a negative effect on later lung function, which is in turn influenced by acute pollen exposures.