Determinants of maximally attained level of pulmonary function

Predictors of lung function in early adulthood: A population-based cohort study

BACKGROUND AND OBJECTIVE

Lung function reaches a peak/plateau in early adulthood before declining with age. Lower early adult lung function may increase the risk for chronic obstructive pulmonary disease (COPD) in mid-late adult life. Understanding the effects of multiple childhood/adolescent exposures and their potential interactions on plateau lung function would provide insights into the natural history of COPD.

METHODS

Longitudinal spirometry data from 688 participants with complete data from a population-based birth cohort (original n = 1037) were used to investigate associations between a wide range of childhood/adolescent exposures and repeated measures of FEV1, FVC and FEV1/FVC during the early-adult plateau phase. Generalized estimating equations were used to accommodate the multiple timepoints per participant.

RESULTS

FEV1 reached a peak/plateau between ages 18 and 26 and FVC from 21 to 32 years, whereas FEV1/FVC declined throughout early adulthood. Childhood asthma and airway hyperresponsiveness were associated with lower early adult FEV1 and FEV1/FVC. Smoking by age 18 was associated with lower FEV1/FVC. Higher BMI during early adulthood was associated with lower FEV1 and FVC and lower FEV1/FVC. Physical activity during adolescence was positively associated with FEV1 and FEV1/FVC but this was only statistically significant in men. There was no convincing evidence of interactions between exposures.

CONCLUSION

Childhood asthma and airway hyperresponsiveness are associated with lower lung function in early adulthood. Interventions targeting these may reduce the risk of COPD in mid-late adult life. Promotion of physical activity during adolescence, prevention of cigarette smoking and maintenance of a healthy body weight in early adulthood are also priorities.

Novel Lung Growth Strategy with Biological Therapy Targeting Airway Remodeling in Childhood Bronchial Asthma

Anti-inflammatory therapy, centered on inhaled steroids, suppresses airway inflammation in asthma, reduces asthma mortality and hospitalization rates, and achieves clinical remission in many pediatric patients. However, the spontaneous remission rate of childhood asthma in adulthood is not high, and airway inflammation and airway remodeling persist after remission of asthma symptoms. Childhood asthma impairs normal lung maturation, interferes with peak lung function in adolescence, reduces lung function in adulthood, and increases the risk of developing chronic obstructive pulmonary disease (COPD). Early suppression of airway inflammation in childhood and prevention of asthma exacerbations may improve lung maturation, leading to good lung function and prevention of adult COPD. Biological drugs that target T-helper 2 (Th2) cytokines are used in patients with severe pediatric asthma to reduce exacerbations and airway inflammation and improve respiratory function. They may also suppress airway remodeling in childhood and prevent respiratory deterioration in adulthood, reducing the risk of COPD and improving long-term prognosis. No studies have demonstrated a suppressive effect on airway remodeling in childhood severe asthma, and further clinical trials using airway imaging analysis are needed to ascertain the inhibitory effect of biological drugs on airway remodeling in severe childhood asthma. In this review, we describe the natural prognosis of lung function in childhood asthma and the risk of developing adult COPD, the pathophysiology of allergic airway inflammation and airway remodeling via Th2 cytokines, and the inhibitory effect of biological drugs on airway remodeling in childhood asthma.

Uncontrolled asthma from childhood to young adulthood associates with airflow obstruction

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 F_ENO (≥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 F_ENO (regression coefficient −0.207; 95% CI −0.342 to −0.073; p=0.002), in contrast to males and participants with normal F_ENO.

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 F_ENO and in females, could have important implications for future lung health.https://bit.ly/3pHkleN

Blood eosinophils associate with reduced lung function growth in adolescent asthmatics

Background and Objective

Some children with asthma have low lung growth, putting them at increased risk for COPD later in life. However, it is currently not clear who will experience this adverse growth pattern. We therefore investigated the predictive role of blood eosinophils as a type 2 inflammation marker in lung growth, focusing on the presence and severity of asthma.

Methods

We investigated blood eosinophils and lung function growth (percentage of predicted values) using linear mixed models in children and adolescents from two longitudinal cohorts. One cohort was hospital‐based and consisted of asthmatic children at their first outpatient clinic visit after referral by the general practitioner (n = 133, mean age 9.8), while the second was a general population‐based birth cohort (PIAMA, asthma n = 52 and non‐asthma n = 433, mean age 8.1). The hospital‐based cohort had not been treated with inhaled corticosteroids (ICS) before referral.

Results

Subjects in the hospital‐based asthma cohort had more severe asthma compared with the asthmatic subjects in the population‐based cohort, defined by lower lung function levels and a higher prevalence of bronchial hyper‐responsiveness. In the asthma cohort, higher blood eosinophil numbers were associated with less growth in FEV₁ (estimated change in lung function per 1 unit increase in ln blood eosinophils (B): −0.66%/year (95% confidence interval (CI): −1.11 to −0.20, p < .01)) and FVC (B: −0.40%/year (95% CI: −0.75 to −0.05), p = .025)) during follow‐up in adolescence (min 7, max 17 years). These associations were not observed in the general population‐based birth cohort, regardless of asthma status during follow‐up (age 8–16).

Conclusions and Clinical Relevance

Blood eosinophil counts in children with asthma not treated with ICS at referral were predictive of lower growth in FEV₁ and FVC during follow‐up in adolescence. Our findings indicate that this association is dependent on the degree of asthma severity. Future studies should address whether anti‐eosinophilic treatments preserve lung function growth in children with asthma.

Inflammatory patterns in fixed airflow obstruction are dependent on the presence of asthma

RATIONALE

Fixed airflow obstruction (FAO) can complicate asthma. Inflammation is a proposed underlying mechanism.

OBJECTIVE

Our aim in this cross-sectional investigation was to evaluate the blood leucocyte pattern and level of exhaled nitric oxide in asthmatics and non-asthmatics with or without FAO.

METHODS

A total of 11,579 individuals aged ≥20 years from the US National Health and Nutrition Examination Survey were included. They were grouped as: controls without asthma and FAO (n = 9,935), asthmatics without FAO (n = 674), asthmatics with FAO (n = 180) and non-asthmatics with FAO (n = 790). FAO was defined as post-bronchodilator FEV1/FVC < lower limit of normal. Exhaled nitric oxide ≥ 25ppb, blood eosinophil levels ≥300 cells/μL, and blood neutrophil levels ≥5100 cells/μL were defined as elevated. Stratified analyses for smoking and smoking history were performed.

RESULTS

Elevated blood eosinophil levels were more common in all groups compared to the controls, with the highest prevalence in the group with asthma and fixed airflow obstruction (p<0.01). In a multiple logistic regression model adjusted for potential confounders including smoking, the asthma groups had significantly higher odds ratios for elevated B-Eos levels compared to the control group (odds ratio 1.4, (confidence interval: 1.1-1.7) for the asthma group without fixed airflow obstruction and 2.5 (1.4-4.2) for the asthma group with fixed airflow obstruction). The group with fixed airflow obstruction without asthma had higher odds ratio for elevated blood neutrophil levels compared to the controls: 1.4 (1.1-1.8). Smoking and a history of smoking were associated to elevated B-Neu levels.

CONCLUSION

Fixed airflow obstruction in asthma was associated with elevated blood eosinophil levels, whereas fixed airflow obstruction without asthma was associated with elevated blood neutrophil levels.

Blood eosinophil level and lung function trajectories: cross-sectional and longitudinal studies in European cohorts

Background

Elevated blood eosinophils have been associated with lower lung function and are believed to be associated with accelerated lung function decline.

Method

Blood eosinophils were measured in four cohorts: <45 years cohort within the Vlagtwedde–Vlaardingen (V&V) study, the Uppsala cohort of the European Community Respiratory Health Survey (ECRHS-Uppsala; <45 years), ≥45 years cohort within the V&V study, and the Rotterdam study (≥45 years). Blood eosinophils at baseline were classified as normal (<300 cells·μL⁻¹) or elevated (≥300 cells·μL⁻¹). Lung function was measured at baseline and follow-up with spirometry: forced expiratory volume in 1 s (FEV₁), vital capacity (VC) and their ratio FEV₁/VC. The association between blood eosinophils and lung function was tested cross-sectionally using linear regression and longitudinally using a mixed model, both adjusted for age, sex, height, pack-years smoking and smoking status. Stratified analyses were done for asthma.

Results

Elevated blood eosinophils were associated with lower FEV₁ (regression coefficient −147 mL (95% CI −188 to −105 mL)), VC (−120 mL (−165 to −75 mL)) and FEV₁/VC (−1.3% (−1.9% to −0.6%)) at baseline in the two <45 years cohorts, and with lower FEV₁ (−70 mL (−112 to −27 mL)) and FEV₁/VC (−1.8% (−2.6% to −1.0%)) in the two ≥45 years cohorts. Elevated blood eosinophils were associated with an accelerated decline in FEV₁ (−5.5 mL·year⁻¹ (95% CI −10.5 to −0.5 mL·year⁻¹)) and VC (−6.4 mL·year⁻¹ (−11.26 to −1.5 mL·year⁻¹)) compared to normal blood eosinophils in the younger asthmatic subjects in the longitudinal studies.

Conclusion

Elevated blood eosinophils are associated with lower lung function in the general population and with an accelerated lung function decline among asthmatic individuals.

Elevated blood eosinophils (≥300 cells per μL) associate with lower lung function in an adult general population and with a worse lung function trajectory in adult asthmatic individualshttps://bit.ly/3fJJ10h

The etiologic origins for chronic obstructive pulmonary disease

COPD, characterized by long-term poorly irreversible airway limitation and persistent respiratory symptoms, has resulted in enormous challenges to human health worldwide, with increasing rates of prevalence, death, and disability. Although its origin was thought to be in the interactions of genetic with environmental factors, the effects of environmental factors on the disease during different life stages remain little known. Without clear mechanisms and radical cure for it, early screening and prevention of COPD seem to be important. In this review, we will discuss the etiologic origins for poor lung function and COPD caused by specific adverse effects during corresponding life stages, as well as try to find new insights and potential prevention strategies for this disease.

Childhood asthma is a risk factor for the development of chronic obstructive pulmonary disease

PURPOSE OF REVIEW

This review will catalog the many recent longitudinal studies that have investigated the relationship between asthma and lung function, or the persistence and trajectories of lung function deficits.

RECENT FINDINGS

Recent work has reported on 50-year follow-ups of some prominent population cohorts. A history of asthma confers a 10-30-fold risk of chronic obstructive pulmonary disease. Individuals reaching a reduced maximum growth of forced expiratory volume in 1 s in early adulthood are at risk for early or more severe chronic obstructive pulmonary disease (COPD).

SUMMARY

Taken together, there is a wealth of overlapping cohort studies of lung function, asthma and COPD. These show that asthma is associated with reduced lung function, which may start in infancy or prenatally, persists through childhood and adulthood and predisposes for early or more severe COPD.

Genetics and Genomics of Longitudinal Lung Function Patterns in Individuals with Asthma

RATIONALE

Patterns of longitudinal lung function growth and decline in childhood asthma have been shown to be important in determining risk for future respiratory ailments including chronic airway obstruction and chronic obstructive pulmonary disease.

OBJECTIVES

To determine the genetic underpinnings of lung function patterns in subjects with childhood asthma.

METHODS

We performed a genome-wide association study of 581 non-Hispanic white individuals with asthma that were previously classified by patterns of lung function growth and decline (normal growth, normal growth with early decline, reduced growth, and reduced growth with early decline). The strongest association was also measured in two additional cohorts: a small asthma cohort and a large chronic obstructive pulmonary disease metaanalysis cohort. Interaction between the genomic region encompassing the most strongly associated single-nucleotide polymorphism and nearby genes was assessed by two chromosome conformation capture assays.

MEASUREMENTS AND MAIN RESULTS

An intergenic single-nucleotide polymorphism (rs4445257) on chromosome 8 was strongly associated with the normal growth with early decline pattern compared with all other pattern groups (P = 6.7 × 10-9; odds ratio, 2.8; 95% confidence interval, 2.0-4.0); replication analysis suggested this variant had opposite effects in normal growth with early decline and reduced growth with early decline pattern groups. Chromosome conformation capture experiments indicated a chromatin interaction between rs4445257 and the promoter of the distal CSMD3 gene.

CONCLUSIONS

Early decline in lung function after normal growth is associated with a genetic polymorphism that may also protect against early decline in reduced growth groups. Clinical trial registered with www.clinicaltrials.gov (NCT00000575).

Eosinophil Count Is a Common Factor for Complex Metabolic and Pulmonary Traits and Diseases: The LifeLines Cohort Study

There is ongoing debate on the association between eosinophil count and diseases, as previous studies were inconsistent. We studied the relationship of eosinophil count with 22 complex metabolic, cardiac, and pulmonary traits and diseases. From the population-based LifeLines Cohort Study (N = 167,729), 13,301 individuals were included. We focused on relationship of eosinophil count with three classes of metabolic (7 traits, 2 diseases), cardiac (6 traits, 2 diseases), and pulmonary (2 traits, 2 diseases) outcomes. Regression analyses were applied in overall, women and men, while adjusted for age, sex, BMI and smoking. A p-value of <0.00076 was considered statistically significant. 58.2% of population were women (mean±SD 51.3±11.1 years old). In overall, one-SD higher of ln-eosinophil count was associated with a 0.04 (±SE ±0.002;p = 6.0×10⁻⁶) SD higher levels in ln-BMI, 0.06 (±0.007;p = 3.1×10⁻¹²) SD in ln-TG, 0.04 (±0.003;p = 7.0×10⁻⁶) SD in TC, 0.04 (±0.004;p = 6.3×10⁻⁷) SD in LDL, 0.04 (±0.006;p = 6.0×10⁻⁶) SD in HbA1c; and with a 0.05 (±0.004;p = 1.7×10⁻⁸) SD lower levels in HDL, 0.05 (±0.007;p = 3.4×10⁻²³) SD in FEV1, and 0.09 (±0.001;p = 6.6×10⁻²⁸) SD in FEV1/FVC. A higher ln-eosinophil count was associated with 1.18 (95%CI 1.09–1.28;p = 2.0×10⁻⁵) odds ratio of obesity, 1.29 (1.19–1.39;p = 1.1×10⁻¹⁰) of metabolic syndrome, 1.40 (1.25–1.56;p = 2.7×10⁻⁹) of COPD and 1.81 (1.61–2.03;p = 1.0×10⁻²³) of asthma. Similar results were found in women. We found no association between ln-eosinophil count either with blood pressure indices in overall, women and men; or with BMI, LDL, HbA1c and obesity in men. In a large population based cohort, we confirmed eosinophil count as a potential factor implicated in metabolic and pulmonary outcomes.

Whole genome prediction and heritability of childhood asthma phenotypes

Introduction

While whole genome prediction (WGP) methods have recently demonstrated successes in the prediction of complex genetic diseases, they have not yet been applied to asthma and related phenotypes. Longitudinal patterns of lung function differ between asthmatics, but these phenotypes have not been assessed for heritability or predictive ability. Herein, we assess the heritability and genetic predictability of asthma‐related phenotypes.

Methods

We applied several WGP methods to a well‐phenotyped cohort of 832 children with mild‐to‐moderate asthma from CAMP. We assessed narrow‐sense heritability and predictability for airway hyperresponsiveness, serum immunoglobulin E, blood eosinophil count, pre‐ and post‐bronchodilator forced expiratory volume in 1 sec (FEV₁), bronchodilator response, steroid responsiveness, and longitudinal patterns of lung function (normal growth, reduced growth, early decline, and their combinations). Prediction accuracy was evaluated using a training/testing set split of the cohort.

Results

We found that longitudinal lung function phenotypes demonstrated significant narrow‐sense heritability (reduced growth, 95%; normal growth with early decline, 55%). These same phenotypes also showed significant polygenic prediction (areas under the curve [AUCs] 56% to 62%). Including additional demographic covariates in the models increased prediction 4–8%, with reduced growth increasing from 62% to 66% AUC. We found that prediction with a genomic relatedness matrix was improved by filtering available SNPs based on chromatin evidence, and this result extended across cohorts.

Conclusions

Longitudinal reduced lung function growth displayed extremely high heritability. All phenotypes with significant heritability showed significant polygenic prediction. Using SNP‐prioritization increased prediction across cohorts. WGP methods show promise in predicting asthma‐related heritable traits.

Concordance between bronchial hyperresponsiveness, fractional exhaled nitric oxide, and asthma control in children

BACKGROUND

Previous studies on association between level of asthma control, markers of airway inflammation and the degree of bronchial hyperresponsiveness (BHR) have yielded conflicting results. Our aim was to determine the presence and severity of BHR and the concordance between BHR, asthma control, and fractional exhaled nitric oxide (FeNO) in children with asthma on therapy.

METHODS

In this cross-sectional observational study, children (aged 6-18 years) with asthma on British Thoracic Society (BTS) treatment steps 2 or 3, underwent comprehensive assessment of their asthma control (clinical assessment, spirometry, asthma control test [ACT], Pediatric Asthma Quality of Life Questionnaire [PAQLQ]), measurement of FeNO and BHR (using mannitol dry powder bronchial challenge test [MCT], Aridol™, Pharmaxis, Australia).

RESULTS

Fifty-seven children (63% male) were studied. Twenty-seven children were on BTS treatment step 2 and 30 were on step 3. Overall, 25 out of 57 (43.8%) children had positive MCT. Of note, 9 out of 27 (33.3%) children with clinically controlled asthma had positive MCT. Analyses of pair-wise agreement between MCT (positive or negative), FeNO (>25 or ≤25 ppb) and clinical assessment of asthma control (controlled or partially controlled/uncontrolled) showed poor agreement between these measures.

CONCLUSIONS

A substantial proportion of children with asthma have persistent BHR despite good clinical control. The concordance between clinical assessment of asthma control, BHR and FeNO was observed to be poor. Our findings raise concerns in the context of emerging evidence for the role of bronchoconstriction in inducing epithelial stress that may drive airway remodeling in asthma. Pediatr Pulmonol. 2016;51:1004-1009. © 2016 Wiley Periodicals, Inc.

Patterns of Growth and Decline in Lung Function in Persistent Childhood Asthma

BACKGROUND

Tracking longitudinal measurements of growth and decline in lung function in patients with persistent childhood asthma may reveal links between asthma and subsequent chronic airflow obstruction.

METHODS

We classified children with asthma according to four characteristic patterns of lung-function growth and decline on the basis of graphs showing forced expiratory volume in 1 second (FEV1), representing spirometric measurements performed from childhood into adulthood. Risk factors associated with abnormal patterns were also examined. To define normal values, we used FEV1 values from participants in the National Health and Nutrition Examination Survey who did not have asthma.

RESULTS

Of the 684 study participants, 170 (25%) had a normal pattern of lung-function growth without early decline, and 514 (75%) had abnormal patterns: 176 (26%) had reduced growth and an early decline, 160 (23%) had reduced growth only, and 178 (26%) had normal growth and an early decline. Lower baseline values for FEV1, smaller bronchodilator response, airway hyperresponsiveness at baseline, and male sex were associated with reduced growth (P<0.001 for all comparisons). At the last spirometric measurement (mean [±SD] age, 26.0±1.8 years), 73 participants (11%) met Global Initiative for Chronic Obstructive Lung Disease spirometric criteria for lung-function impairment that was consistent with chronic obstructive pulmonary disease (COPD); these participants were more likely to have a reduced pattern of growth than a normal pattern (18% vs. 3%, P<0.001).

CONCLUSIONS

Childhood impairment of lung function and male sex were the most significant predictors of abnormal longitudinal patterns of lung-function growth and decline. Children with persistent asthma and reduced growth of lung function are at increased risk for fixed airflow obstruction and possibly COPD in early adulthood. (Funded by the Parker B. Francis Foundation and others; ClinicalTrials.gov number, NCT00000575.).

Diagnosis, assessment, and phenotyping of COPD: beyond FEV₁

COPD is now widely recognized as a complex heterogeneous syndrome, having both pulmonary and extrapulmonary features. In clinical practice, the diagnosis of COPD is based on the presence of chronic airflow limitation, as assessed by post-bronchodilator spirometry. The severity of the airflow limitation, as measured by percent predicted FEV1, provides important information to the physician to enable optimization of management. However, in order to accurately assess the complexity of COPD, there need to be other measures made beyond FEV1. At present, there is a lack of reliable and simple blood biomarkers to confirm and further assess the diagnosis of COPD. However, it is possible to identify patients who display different phenotypic characteristics of COPD that relate to clinically relevant outcomes. Currently, validated phenotypes of COPD include alpha-1 antitrypsin deficiency, and "frequent exacerbators". Recently, a definition and assessment of a new phenotype comprising patients with overlapping features of asthma and COPD has been suggested and is known as "asthma COPD overlap syndrome". Several other phenotypes have been proposed, but require validation against clinical outcomes. Defining phenotypes requires the assessment of multiple factors indicating disease severity, its impact, and its activity. Recognition and validation of COPD phenotypes has an important role to play in the selection of evidence-based targeted therapy in the future management of COPD, but regardless of the diagnostic terms, patients with COPD should be assessed and treated according to their individual treatable characteristics.

Revisiting the Dutch hypothesis

The Dutch hypothesis was first articulated in 1961, when many novel and advanced scientific techniques were not available, such as genomics techniques for pinpointing genes, gene expression, lipid and protein profiles, and the microbiome. In addition, computed tomographic scans and advanced analysis techniques to dissect (small) airways disease and emphysema were not available. At that time, the group of researchers under the visionary guidance of Professor N. G. M. Orie put forward that both genetic and environmental factors can determine whether one would have airway obstructive diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Moreover, they stipulated that the phenotype of obstructive airway disease could be affected by sex and changes with aging. Orie and colleagues' call to carefully phenotype patients with obstructive airways diseases has been adopted by many current researchers in an attempt to determine the heterogeneity of both asthma and COPD to better define these diseases and optimize their treatment. The founders of the Dutch hypothesis were far ahead of their time, and we can learn from their insights. We should fully characterize all patients in our clinical practice and not just state that they have asthma, COPD, or asthma and COPD overlap syndrome. This detailed phenotyping can help in understanding these obstructive airway diseases and provide guidance for disease management.

Early chronic obstructive pulmonary disease: definition, assessment, and prevention

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. COPD, however, is a heterogeneous collection of diseases with differing causes, pathogenic mechanisms, and physiological effects. Therefore a comprehensive approach to COPD prevention will need to address the complexity of COPD. Advances in the understanding of the natural history of COPD and the development of strategies to assess COPD in its early stages make prevention a reasonable, if ambitious, goal.

Dyspnea as an independent predictor of mortality

BACKGROUND AND AIM

Dyspnea is a common and easily elicited presenting complaint in patients seen by physicians who evaluate and take care of chronic respiratory disorders. Although dyspnea is subjective and tends to increase with age or reduced lung function, it appears to be reproducible as a symptom and often signifies serious underlying disease.

METHODS

Systematic review of longitudinal studies with dyspnea as the exposure and mortality as the outcome; age, smoking and lung function had to be controlled for to be included in the review. In addition, a minimum sample size at baseline of 500 subjects was required for each study.

RESULTS

From over 3000 potential references, 10 longitudinal studies met all criteria and were included. All 10 studies suggested that dyspnea was an independent predictor of mortality with point estimates by odds ratio, rate ratio or hazard ratios ranging from 1.3 up to 2.9-fold greater than baseline. All 10 studies had actual or implied 95% confidence interval bands greater than the null value of one.

CONCLUSION

Dyspnea, a symptom, predicts mortality and is a proxy for underlying diseases, most often of heart and lung. Therefore, chronic dyspnea needs to be evaluated as to etiology to allow for treatment to minimize morbidity and mortality when possible.

Airway hyperresponsiveness and development of lung function in adolescence and adulthood

BACKGROUND

Long-term longitudinal studies of lung function from childhood to adulthood are important in linking our understanding of childhood risk factors to adult disease. Airway hyperresponsiveness has been shown to independently affect lung function growth in studies of adolescence. The objective of the study was to test the hypothesis that airway hyperresponsiveness has an independent deleterious effect on lung function in adolescence that extends into adulthood.

METHODS

A random population sample (n = 983) aged 7-17 from Copenhagen was followed longitudinally for 20 years with four examinations.

RESULTS

A total of 780 (79.3%) subjects contributed with lung function measurements and bronchial provocation testing. Among these, 170 (21.8%) had airway hyperresponsiveness at one examination or more during the study period. There was no difference in initial FEV1 levels between subjects with and without airway hyperresponsiveness. In a repeated measures regression model with adjustment for asthma and smoking, airway hyperresponsiveness was independently associated with reduced rates of growth in lung function in both sexes of 23 ml/year. Reduced growth rates resulted in deficits in maximal attained level of lung function at age 18, which persisted throughout the follow-up until the last examination at age 27-37 years.

CONCLUSION

Airway hyperresponsiveness has an independent deleterious effect on lung function development from 7 to 37 years resulting in a lower maximal attained lung function and persistent deficits in lung function in adulthood.

Variations in FEV₁ decline over time in chronic obstructive pulmonary disease and its implications

PURPOSE OF REVIEW

This article reviews findings from longitudinal observational studies in both general and chronic obstructive pulmonary disease (COPD) populations, as well as from intervention trials in COPD, in which the annual rate of decline in forced expired volume in 1  s (FEV₁) has been measured. The purpose of the review is to describe the individual variability in rates of decline in FEV₁ within these populations, explore the factors contributing to this variability and discuss its implications.

RECENT FINDINGS

Individual rates of decline in FEV₁ have been found to vary considerably across participants with COPD in both observational cohorts and intervention trials from decreases as rapid as 150-200  ml per year to increases of up to approximately 150  ml per year, with mean rates of decline ranging from 33 to 69  ml per year. Aside from technical and biologic (e.g., time of day, season, weather, fatigue) sources of variation, other influential factors have included smoking status (most notably current versus former smoking), baseline smoking intensity, baseline lung function, airway hyperresponsiveness, exacerbation frequency, and, variably, age and sex. The presence of emphysema may also be a determinant, as well as certain biomarkers and gene variants.

SUMMARY

The wide distribution of individual rates of decline in FEV₁ includes especially rapid and slow declines. Future research is needed to identify biomarkers that both are predictive of a rapid decline within individuals who might then be targeted for special intervention and might also serve as surrogate endpoints in interventional trials.

HIV-infected adolescent, young adult and pregnant smokers: important targets for effective tobacco control programs

Tobacco use is inextricably linked to a number of health risks both in the general and HIV-infected populations. There is, however, a dearth of research on effective tobacco control programs among people living with HIV, and especially among adolescents, young adults and pregnant women, groups with heightened or increased vulnerability secondary to tobacco use. Adolescents and young adults constitute a growing population of persons living with HIV infection. Early and continued tobacco use in this population living with a disease characterized by premature onset multimorbidity and chronic inflammation is of concern. Additionally, there is an increased acuity for tobacco control among HIV-infected pregnant women to reduce pregnancy morbidity and improve fetal outcome. This review will provide an important summary of current knowledge of tobacco use among HIV-infected adolescents, young adults and pregnant women. The effects of tobacco use in these specific populations will be presented and the current state of tobacco control within these populations, assessed.

Kidney function and tobacco smoke exposure in US adolescents

BACKGROUND AND OBJECTIVE

Active smoking and secondhand smoke (SHS) are known risk factors for kidney disease in adults. We evaluated the association between exposure to active smoking or SHS and kidney function in US adolescents.

METHODS

This is a cross-sectional study in 7516 adolescents aged 12-17 who participated in NHANES 1999-2010 and had serum creatinine and cotinine measures. Active smoking was defined as self-reported smoking or serum cotinine concentrations >10 ng/mL. SHS was defined as nonactive smokers who self-reported living with ≥1 smokers or serum cotinine concentrations ≥ 0.05 ng/mL. Kidney function was determined by using the chronic kidney disease in children estimated glomerular filtration rate (eGFR) equation.

RESULTS

Median (interquartile range) eGFR and serum cotinine concentrations were 96.8 (85.4-109.0) mL/minute per 1.73 m(2) and 0.07 (0.03-0.59) ng/mL, respectively. After multivariable adjustment, eGFR decreased 1.1 mL/minute per 1.73 m(2) (95% confidence interval [CI]: -1.8 to -0.3) per interquartile range increase in serum cotinine concentrations. The mean (95%CI) difference in eGFR for serum cotinine tertiles 1, 2, and 3 among children exposed to SHS compared to unexposed were -0.4 (-1.9 to 1.2), -0.9 (-2.7 to 0.9), and -2.2 (-4.0 to -0.4) mL/minute per 1.73 m(2), respectively (P = .03). The corresponding values among tertiles of active smokers compared to unexposed were 0.2 (-2.2 to 2.6), -1.9 (-3.8 to 0.0), and -2.6 (-4.6 to -0.6) mL/minute per 1.73 m(2) (P = .01).

CONCLUSIONS

Tobacco smoke exposure was associated with decreased eGFR in US adolescents, supporting the possibility that tobacco smoke effects on kidney function begin in childhood.

Risk factors for asthma in a helminth endemic area in bahia, Brazil

Protective factors associated with atopy or asthma in rural areas include socioeconomic level, overcrowding, and helminth infection. However, little epidemiological information was originated from schistosomiasis areas. This study aimed to investigate factors associated with asthma in a schistosomiasis endemic area. A questionnaire was used to obtain information on demographics, socioeconomic, and environmental features. The ISAAC questionnaire was used to identify individuals with asthma. Parasitological exam was done in all participants and skin prick test to aeroallergens in all asthmatics. Prevalence of Schistosoma mansoni infection was 57.4% and Ascaris lumbricoides, 30.8%. Asthma was found in 13.1% of the population, and 35.1% of them had a positive SPT. Active and passive smoking was positively associated with asthma, whereas A. lumbricoides was negatively associated. In a schistosomiasis hyperendemic region, current infection with A. lumbricoides is protective against asthma. However, we cannot rule out the involvement of S. mansoni infection in this process.

Genetics of maximally attained lung function: a role for leptin?

OBJECTIVES

To estimate the heritabilities of maximally attained lung function in young adult twins, and to examine whether circulating leptin, leptin (LEP) and leptin receptor (LEPR) gene polymorphisms are associated with maximally attained lung function.

METHODS

Measures on forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC) were available of 578 twins recruited from the East Flanders Prospective Twin Survey (165 monozygotic (MZ) and 73 dizygotic (DZ) complete pairs and 102 single twins). Twin model fitting and (genetic) association analyses were performed.

RESULTS

Intra-pair correlations of FEV(1) and FVC did not differ significantly between MZ monochorionic and MZ dichorionic pairs. Heritability estimates of FEV(1) and FVC were 69% and 63%, respectively. The A allele of the LEP 19G>A SNP was significantly associated with a lower FEV(1) (p(Additive) = 0.01) and FVC (p(Dominant) = 0.047), while the LEPR K109R and Q223R SNPs showed no associations. Accounting for body mass index, serum leptin was negatively associated with FVC (p = 0.02) in men, but not in women.

CONCLUSIONS

More than 60% of variation in maximally attained FEV(1) and FVC is explained by genetic factors. Moreover, these results suggest that leptin may be important in the determination of maximally attainable lung function.

New-onset asthma and the effect of environment and occupation among farming and nonfarming rural subjects

BACKGROUND

Many factors, including environmental exposures, have been related to the increase in the prevalence of asthma, but only few have been tested for in longitudinal studies.

OBJECTIVE

We studied farming students to determine whether their environment during childhood and as adults was a factor determining subsequent onset of asthma.

METHODS

From 1994 to 1998, new cases of asthma were identified by means of an annual posted questionnaire followed by a telephone interview in a prospective cohort consisting of 1964 farming-school students and 407 nonfarming subjects aged 16 to 26 years. For each case, we selected a control subject from the cohort with no asthma in a case-based design, and all underwent an interview and a clinical examination.

RESULTS

We found 122 new cases of asthma. In a multiple regression model the odds ratio for new asthma was 3.3 (95% CI, 1.7-6.3) for smoking; 3.4 (95% CI, 1.6-7.0), 2.5 (95% CI, 1.1-5.3), and 7.0 (95% CI, 1.2-41.6) for exposure to swine, dairy production, and welding, respectively; and 11.7 (95% CI, 2.4-56.4) for bronchial hyperresponsiveness at baseline. Being born and raised on a farm significantly reduced the risk odds ratio (0.5 [95% CI, 0.3-0.98]), whereas atopy had no influence.

CONCLUSION

Exposure to swine and dairy confinements, welding, smoking, and bronchial hyperresponsiveness are risk factors for nonallergic asthma, and being born and raised on a farm reduces the subsequent risk. These findings support the theory that immune and inflammatory responses can be influenced by environmental exposure to early childhood, reducing the risk of asthma later in life.

Systematic review of the evidence relating FEV1 decline to giving up smoking

BACKGROUND

The rate of forced expiratory volume in 1 second (FEV1) decline ("beta") is a marker of chronic obstructive pulmonary disease risk. The reduction in beta after quitting smoking is an upper limit for the reduction achievable from switching to novel nicotine delivery products. We review available evidence to estimate this reduction and quantify the relationship of smoking to beta.

METHODS

Studies were identified, in healthy individuals or patients with respiratory disease, that provided data on beta over at least 2 years of follow-up, separately for those who gave up smoking and other smoking groups. Publications to June 2010 were considered. Independent beta estimates were derived for four main smoking groups: never smokers, ex-smokers (before baseline), quitters (during follow-up) and continuing smokers. Unweighted and inverse variance-weighted regression analyses compared betas in the smoking groups, and in continuing smokers by amount smoked, and estimated whether beta or beta differences between smoking groups varied by age, sex and other factors.

RESULTS

Forty-seven studies had relevant data, 28 for both sexes and 19 for males. Sixteen studies started before 1970. Mean follow-up was 11 years. On the basis of weighted analysis of 303 betas for the four smoking groups, never smokers had a beta 10.8 mL/yr (95% confidence interval (CI), 8.9 to 12.8) less than continuing smokers. Betas for ex-smokers were 12.4 mL/yr (95% CI, 10.1 to 14.7) less than for continuing smokers, and for quitters, 8.5 mL/yr (95% CI, 5.6 to 11.4) less. These betas were similar to that for never smokers. In continuing smokers, beta increased 0.33 mL/yr per cigarette/day. Beta differences between continuing smokers and those who gave up were greater in patients with respiratory disease or with reduced baseline lung function, but were not clearly related to age or sex.

CONCLUSION

The available data have numerous limitations, but clearly show that continuing smokers have a beta that is dose-related and over 10 mL/yr greater than in never smokers, ex-smokers or quitters. The greater decline in those with respiratory disease or reduced lung function is consistent with some smokers having a more rapid rate of FEV1 decline. These results help in designing studies comparing continuing smokers of conventional cigarettes and switchers to novel products.

Bone morphogenetic protein 4 enhances canonical transient receptor potential expression, store-operated Ca2+ entry, and basal [Ca2+]i in rat distal pulmonary arterial smooth muscle cells

Recent advances have identified an important role of bone morphogenetic protein 4 (BMP4) in pulmonary vascular remodeling, yet the underlying mechanisms remain largely unexplored. We have previously found that Ca(2+) influx through store-operated calcium channels (SOCC), which are mainly thought to be composed of canonical transient receptor potential (TRPC) proteins, likely contribute to the pathogenic development of chronic hypoxic pulmonary hypertension. In this study, we investigated the effect of BMP4 on expression of TRPC and store-operated Ca(2+) entry (SOCE) in pulmonary arterial smooth muscle cells (PASMCs). Real-time quantitative PCR and Western blotting revealed that treatment with BMP4 (50 ng/ml, 60 h) increased TRPC1, TRPC4, and TRPC6 mRNA and protein expression in growth-arrested rat distal PASMCs. Moreover, in comparison to vehicle control, cells treated with BMP4 also exhibited enhanced SOCE, and elevated basal intracellular calcium concentration ([Ca(2+)](i)) as determined by fluorescent microscopy using the Ca(2+) indicator Fura-2 AM. Perfusing cells with Ca(2+)-free Krebs-Ringer bicarbonate solution (KRBS) or KRBS containing SOCC antagonists SKF-96365 or NiCl(2) attenuated the increases in basal [Ca(2+)](i) caused by BMP4. Specific knockdown of BMP4 by small interference RNA significantly decreased the mRNA and protein expression of TRPC1, TRPC4, and TRPC6 and reduced SOCE and basal [Ca(2+)](i) in serum-stimulated PASMCs. We conclude that BMP4 regulates calcium signaling in PASMCs likely via upregulation of TRPC expression, leading to enhanced SOCE and basal [Ca(2+)](i) in PASMCs, and by this mechanism contributes to pulmonary vascular remodeling during pulmonary arterial hypertension.

Increasing Evidence for Gender Differences in Chronic Obstructive Pulmonary Disease

The prevalence of chronic obstructive pulmonary disease (COPD) among women is increasing and differences in both the management of COPD and the results of treatment between men and women have been noted. This article investigates the reasons for this increase in prevalence and the differences in natural history and COPD management between male and female patients. The main reason for the rise in prevalence of COPD in women is increased tobacco use. An additional factor is the greater susceptibility of women to damage from smoke and air pollution. The health-related quality of life is worse in women when compared with men with the same severity of disease. In addition, nutritional status is often worse in women. The most important treatment for COPD is to stop smoking. Women appear to be more dependent on cigarettes than men, and have greater difficulties stopping smoking, especially when they live with a partner who smokes. Rehabilitation is an effective treatment for both male and female COPD patients, but the focus is different: women need more emotional support and social interaction to achieve the best results.

The natural history of chronic airflow obstruction revisited: an analysis of the Framingham offspring cohort

RATIONALE

Understanding normal lung development and aging in health and disease, both in men and in women, is essential to interpreting any therapeutic intervention.

OBJECTIVES

We aimed to describe lung function changes in healthy never-smoking males and females, from adolescence to old age, and to determine the effects of smoking and those derived from quitting.

METHODS

Prospective cohort study within all participants of the Framingham Offspring cohort who had two or more valid spirometry measurements during follow-up (n = 4,391; age range at baseline 13 to 71 yr), with a median follow-up time of 23 years.

MEASUREMENTS AND MAIN RESULTS

To best fit the curves describing FEV(1) changes with age to raw data, we used a generalized additive model with smooth terms and incorporating the subject-specific (longitudinal) random effects. We found that: (1) healthy never-smoker females achieve full lung growth earlier than males, and their rate of decline with age was slightly, but not significantly, lower; (2) smoking increases the rate of lung function decline, both in males and in females; (3) there is a range of susceptibility to the effects of smoking. The presence of respiratory symptoms at baseline and/or a respiratory diagnosis during follow-up appears to identify a group of susceptible smokers; and (4) quitting smoking has a beneficial effect at any age, but it is more pronounced in earlier quitters.

CONCLUSIONS

Lung function changes from adolescence to old age differ in males and females, smoking has similar deleterious effects in both sexes, and quitting earlier is better.

Child abuse and smoking among young women: the importance of severity, accumulation, and timing

PURPOSE

We examined the association between severity, accumulation, and timing of abuse in childhood and adolescence and smoking status among young women.

METHODS

Retrospective self-reported childhood abuse was ascertained with the modified Conflict Tactics Scale from 91,286 Nurses Health Study II participants in 2001 (68,505 returned; 75.0% response rate). Childhood abuse was categorized by severity (mile/moderate/severe), type (physical/sexual), and timing (childhood/adolescence). Smoking status during adolescence was reported at baseline (1989). Logistic regression was used to predict smoking initiation by age 14 and smoking status between the ages of 15 and 19.

RESULTS

A graded association between severity of abuse and early initiation of smoking (by age 14 years) was demonstrated (odds ratio [OR] = 1.9, 95% confidence interval [CI] = 1.7-2.1 for severe physical violence). Young women with both physical and sexual abuse were two times more likely to start smoking by age 14 than were those reporting no abuse (OR = 2.0, 95% CI = 1.8-2.3). Although abuse during childhood increased risk for adolescent smoking (OR = 1.7, 95% CI = 1.8-2.1) for those with childhood physical and sexual abuse, inclusion of adolescent physical and sexual abuse (OR = 2.2, 95% CI 2.1-2.4) diminished the impact of childhood abuse (OR = 1.1, 95% CI 1.1-1.2). The degree of familial emotional support was protective against smoking, and reduced the impact of abuse by 40% among those with high emotional support versus those without (p < .0001).

CONCLUSIONS

A strong and graded association was observed between both severity and accumulation of abuse and the risk of early initiation of smoking among girls. Smoking status during late adolescence was more strongly associated with adolescent abuse than childhood abuse. Early smoking onset is associated with both heightened risk for disease in adolescence but also increased morbidity and mortality in adulthood. Identifying and intervening in potentially modifiable risk factors for smoking onset in young women, such as early-life physical and sexual abuse, and building familial strengths, such as emotional support, may have significant public health implications.

The effects of tobacco smoke exposure on respiratory health in school-aged children

The effects of tobacco smoke exposure on the respiratory health of school-aged children relate to persisting effects of exposure to tobacco smoke during pregnancy and early infancy, passive exposure to environmental tobacco smoke in the home and elsewhere, and active smoking during later childhood. Much of the current evidence comes from cross-sectional and longitudinal observational studies and suggests that, for asthma and pulmonary function outcomes, the strongest associations are with smoke exposure in pregnancy and early childhood, although independent effects of later exposure are reported. Exposure in later childhood to environmental tobacco smoke is associated with increased respiratory symptoms, although for some of these, the effect appears to diminish with increasing age of the child. There is currently a paucity of evidence on the long-term adverse respiratory consequences of active smoking by children and adolescents, but such evidence there is suggests that these may be substantial.

Does harboring hostility hurt? Associations between hostility and pulmonary function in the Coronary Artery Risk Development in (Young) Adults (CARDIA) study

OBJECTIVE

To examine the cross-sectional association between hostility and pulmonary function (PF) and its consistency across race/ethnicity-gender groups.

DESIGN

Data were from the Coronary Artery Risk Development in (Young) Adults (CARDIA) cohort study (N=4,629). Participants were recruited from 4 metropolitan areas in the United States, ages 18-30 years at baseline in 1985-1986, approximately balanced across race/ethnicity (Black, White) and gender.

MAIN OUTCOME MEASURES

Main outcome measures were percent predicted values for forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC).

RESULTS

In full-sample multiple linear regression analyses, each 1 standard deviation (SD) increase in hostility was associated with a 0.66% decrease in FEV-sub-1 (p=.0002) and a 0.60% decrease in FVC (p=.0006). This inverse association of hostility with PF remained after controlling for age, height, current socioeconomic status (SES), participant smoking status, and asthma and is more consistent than that of smoking and PF. In stratified analyses, each 1 SD increase in hostility predicted statistically significant reductions in PF for Black women, White women, and Black men. For White men, hostility showed no statistically significant relation with PF, although the pattern relating hostility to PF was similar to the pattern in the other three groups. Further, both of the post hoc three-way interaction terms for hostility, race/ethnicity, and gender predicting FEV-sub-1 and FVC were nonsignificant.

CONCLUSION

PF was inversely associated with hostility across race/ethnicity and gender, independent of age, height, current SES, smoking, and asthma. On the basis of these cross-sectional findings, the authors hypothesize that higher hostility will predict a more rapid decline in PF.

Severe, early-onset emphysema with normal alphal-antitrypsin levels in nonsmokers: a clinical dilemma

Approximately 85% of all cases of chronic obstructive pulmonary disease are attributed to cigarette smoking. The only other established risk factor for the development of chronic obstructive pulmonary disease that is of comparable importance is the deficiency of alpha1-antitrypsin, a rare genetic defect that is present in less than 1% of all cases. Other risk factors are not well characterized in the literature. This article describes one patient without a significant smoking history and with a normal alphaa-antitrypsin level who developed severe early-onset emphysema and gives a brief discussion about other genetic and environmental risk factors for the development of emphysema.

A brief targeted review of susceptibility factors, environmental exposures, asthma incidence, and recommendations for future asthma incidence research

Relative to research on effects of environmental exposures on exacerbation of existing asthma, little research on incident asthma and environmental exposures has been conducted. However, this research is needed to better devise strategies for the prevention of asthma. The U.S. Environmental Protection Agency (EPA) and National Institute of Environmental Health Sciences held a conference in October 2004 to collaboratively discuss a future research agenda in this area. The first three articles in this mini-monograph summarize the discussion on potential putative environmental exposure; they include an overview of asthma and conclusions of the workshop participants with respect to public health actions that could currently be applied to the problem and research needs to better understand and control the induction and incidence of asthma, the potential role of indoor/outdoor air pollutants in the induction of asthma), and biologics in the induction of asthma. Susceptibility is a key concept in the U.S. EPA "Asthma Research Strategy" document and is associated with the U.S. EPA framework of protecting vulnerable populations from potentially harmful environmental exposures. Genetics, age, and lifestyle (obesity, diet) are major susceptibility factors in the induction of asthma and can interact with environmental exposures either synergistically or antagonistically. Therefore, in this fourth and last article we consider a number of "susceptibility factors" that potentially influence the asthmatic response to environmental exposures and propose a framework for developing research hypotheses regarding the effects of environmental exposures on asthma incidence and induction.

Predictors of lung function and its decline in mild to moderate COPD in association with gender: results from the Euroscop study

BACKGROUND

There is increasing appreciation of gender differences in COPD but scant data whether risk factors for low lung function differ in men and women. We analysed data from 3 years follow-up in 178 women and 464 men with COPD, participants in the Euroscop Study who were smokers unexposed to inhaled corticosteroids.

METHODS

Explanatory variables of gender, age, starting age and pack-years smoking, respiratory symptoms, FEV(1)%FVC and FEV(1)%IVC (clinically important measures of airway obstruction), body mass index (BMI), and change in smoking were included in multiple linear regression models with baseline and change in post-bronchodilator FEV(1) as dependent variables.

RESULTS

Reduced baseline FEV(1) was associated with respiratory symptoms in men only. Annual decline in FEV(1) was not associated with respiratory symptoms in either men or women, and was 55 ml less in obese men (BMI 30 kg/m(2)) than men having normal BMI, an effect not seen in women. It was 32 ml faster in women with FEV(1)%FVC<median than women with less airway obstruction, a larger difference than in men (8 ml per year). It was 17.7 ml/year faster when increasing the daily number of cigarettes by 10 in men only, but not significantly greater than in women.

CONCLUSION

Respiratory symptoms were associated with reduced baseline FEV(1) in men with COPD. In men, obesity was associated with reduced decline and increasing the number of cigarettes smoked with increased decline in lung function. In women more severe airway obstruction was associated with accelerated decline.

High altitude pulmonary hypertension: role of K+ and Ca2+ channels

Global alveolar hypoxia, as experienced at high-altitude living, has a serious impact on vascular physiology, particularly on the pulmonary vasculature. The effects of sustained hypoxia on pulmonary arteries include sustained vasoconstriction and enhanced medial hypertrophy. As the major component of the vascular media, pulmonary artery smooth muscle cells (PASMC) are the main effectors of the physiological response(s) induced during or following hypoxic exposure. Endothelial cells, on the other hand, can sense humoral and hemodynamic changes incurred by hypoxia, triggering their production of vasoactive and mitogenic factors that then alter PASMC function and growth. Transmembrane ion flux through channels in the plasma membrane not only modulates excitation- contraction coupling in PASMC, but also regulates cell volume, apoptosis, and proliferation. In this review, we examine the roles of K+ and Ca2+ channels in the pulmonary vasoconstriction and vascular remodeling observed during chronic hypoxia-induced pulmonary hypertension.