COPD in Chinese nonsmokers

Epidemiological evidence relating environmental smoke to COPD in lifelong non-smokers: a systematic review

Background: Some evidence suggests environmental tobacco smoke (ETS) might cause chronic obstructive pulmonary disease (COPD). We reviewed available epidemiological data in never smokers. Methods: We identified epidemiological studies providing estimates of relative risk (RR) with 95% confidence interval (CI) for various ETS exposure indices. Confounder-adjusted RRs for COPD were extracted, or derived using standard methods. Meta-analyses were conducted for each exposure index, with tests for heterogeneity and publication bias. For the main index (spouse ever smoked or nearest equivalent), analyses investigated variation in RR by location, publication period, study type, sex, diagnosis, study size, confounder adjustment, never smoker definition, and exposure index definition. Results: Twenty-eight relevant studies were identified; nine European or Middle Eastern, nine Asian, eight American and two from multiple countries. Five were prospective, seven case-control and 16 cross-sectional. The COPD definition involved death or hospitalisation in seven studies, GOLD stage 1+ criteria in twelve, and other definitions in nine. For the main index, random-effects meta-analysis of 33 heterogeneous (p<0.001) estimates gave a RR of 1.20 (95%CI 1.08-1.34). Higher estimates for females (1.59,1.16-2.19, n=11) than males (1.29,0.94-1.76, n=7) or sexes combined (1.10,0.99-1.22, n=15 where sex-specific not available), and lower estimates for studies of 150+ cases (1.08,0.97-1.20, n=13) partly explained the heterogeneity. Estimates were higher for Asian studies (1.34,1.08-1.67, n=10), case-control studies (1.55,1.04-2.32, n=8), and COPD mortality or hospitalisation (1.40,1.12-1.74, n=11). Some increase was seen for severer COPD (1.29,1.10-1.52, n=7). Dose-response evidence was heterogeneous. Evidence for childhood (0.88,0.72-1.07, n=2) and workplace (1.12,0.77-1.64, n=4) exposure was limited, but an increase was seen for overall adulthood exposure (1.20,1.03-1.39, n=17). We discuss study weaknesses that may bias estimation of the association of COPD with ETS. Conclusions: Although the evidence suggests ETS increases COPD, study weaknesses and absence of well-designed large studies precludes reliable inference of causality. More definitive evidence is required.

Epidemiological evidence relating environmental smoke to COPD in lifelong non-smokers: a systematic review

Background: Some evidence suggests environmental tobacco smoke (ETS) might cause chronic obstructive pulmonary disease (COPD). We reviewed available epidemiological data in never smokers. Methods: We identified epidemiological studies providing estimates of relative risk (RR) with 95% confidence interval (CI) for various ETS exposure indices. Confounder-adjusted RRs for COPD were extracted, or derived using standard methods. Meta-analyses were conducted for each exposure index, with tests for heterogeneity and publication bias. For the main index (spouse ever smoked or nearest equivalent), analyses investigated variation in RR by location, publication period, study type, sex, diagnosis, study size, confounder adjustment, never smoker definition, and exposure index definition. Results: Twenty-eight relevant studies were identified; nine European or Middle Eastern, nine Asian, eight American and two from multiple countries. Five were prospective, seven case-control and 16 cross-sectional. The COPD definition involved death or hospitalisation in seven studies, GOLD stage 1+ criteria in twelve, and other definitions in nine. For the main index, random-effects meta-analysis of 33 heterogeneous (p<0.001) estimates gave a RR of 1.20 (95%CI 1.08-1.34). Higher estimates for females (1.59,1.16-2.19, n=11) than males (1.29,0.94-1.76, n=7) or sexes combined (1.10,0.99-1.22, n=15 where sex-specific not available), and lower estimates for studies of 150+ cases (1.08,0.97-1.20, n=13) partly explained the heterogeneity. Estimates were higher for Asian studies (1.34,1.08-1.67, n=10), case-control studies (1.55,1.04-2.32, n=8), and COPD mortality or hospitalisation (1.40,1.12-1.74, n=11). Some increase was seen for severer COPD (1.29,1.10-1.52, n=7). Dose-response evidence was heterogeneous. Evidence for childhood (0.88,0.72-1.07, n=2) and workplace (1.12,0.77-1.64, n=4) exposure was limited, but an increase was seen for overall adulthood exposure (1.20,1.03-1.39, n=17). We discuss study weaknesses that may bias estimation of the association of COPD with ETS. Conclusions: Although the evidence suggests ETS increases COPD, study weaknesses and absence of well-designed large studies precludes reliable inference of causality. More definitive evidence is required.

Identifying the heterogeneity of COPD by V/P SPECT: a new tool for improving the diagnosis of parenchymal defects and grading the severity of small airways disease

Introduction

Airway obstruction and possible concomitant pulmonary diseases in COPD cannot be identified conventionally with any single diagnostic tool. We aimed to diagnose and grade COPD severity and identify pulmonary comorbidities associated with COPD with ventilation/perfusion single-photon emission computed tomography (V/P SPECT) using Technegas as the functional ventilation imaging agent.

Methods

94 COPD patients (aged 43–86 years, Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages I–IV) were examined with V/P SPECT and spirometry. Ventilation and perfusion defects were analyzed blindly according to the European guidelines. Penetration grade of Technegas in V SPECT measured the degree of obstructive small airways disease. Total preserved lung function and penetration grade of Technegas in V SPECT were assessed by V/P SPECT and compared to GOLD stages and spirometry.

Results

Signs of small airway obstruction in the ventilation SPECT images were found in 92 patients. Emphysema was identified in 81 patients. Two patients had no signs of COPD, but both of them had a pulmonary embolism, and in one of them we also suspected a lung tumor. The penetration grade of Technegas in V SPECT and total preserved lung function correlated significantly to GOLD stages (r=0.63 and −0.60, respectively, P<0.0001). V/P SPECT identified pulmonary embolism in 30 patients (32%). A pattern typical for heart failure was present in 26 patients (28%). Parenchymal changes typical for pneumonia or lung tumor were present in several cases.

Conclusion

V/P SPECT, using Technegas as the functional ventilation imaging agent, is a new tool to diagnose COPD and to grade its severity. Additionally, it revealed heterogeneity of COPD caused by pulmonary comorbidities. The characteristics of these comorbidities suggest their significant impact in clarifying symptoms, and also their influence on the prognosis.

"What are my chances of developing COPD if one of my parents has the disease?" A systematic review and meta-analysis of prevalence of co-occurrence of COPD diagnosis in parents and offspring

Introduction

Intergenerational associations in chronic obstructive pulmonary disease (COPD) have been well recognized and may result from genetic, gene environment, or exposure to life course factors. Consequently, adult offspring of parents with COPD may be at a greater risk of developing COPD. The aim of this study was to review the prevalence of co-occurrence of COPD in adult offspring with one or both parents having COPD independent of specific genetic variations.

Methods

In total, five databases were searched for original studies in which prevalence of COPD was reported in both offspring (children) and one or both parents. Studies were excluded if COPD was not clearly defined, COPD was linked to specific genetic variations, COPD was combined with other chronic respiratory conditions, or estimates included other first-degree relatives. Data extraction (ie, sample characteristics, prevalence of COPD, and odds ratio [OR] if reported) was completed by two independent reviewers. A meta-analysis of prevalence and OR was conducted, where possible.

Results

Of the 3,382 citations, 129 full texts were reviewed to include eight studies (six case–control, one cross-sectional, and one cohort) reflecting either prevalence of COPD in offspring of parents with COPD (descendent approach, n=3), which ranged from 0% to 17.3%, or prevalence of people with COPD reporting positive parental history of COPD (antecedent approach, n=5), for which the pooled prevalence was 28.6%. Offspring of people with COPD had 1.57 times greater odds (95% confidence interval =1.29–1.93; P<0.001) of having COPD compared with people not having a parental history of COPD.

Conclusion

The prevalence of COPD in adult offspring of people with COPD is greater than population-based estimates, and the ORs indicate a higher risk in this group. This offers clinicians a potential strategy for opportunistic screening, early identification, and intervention in this at-risk group.

Asthma-COPD Overlap Syndrome: What We Know and What We Don't

Approximately one in four patients with chronic obstructive pulmonary disease (COPD) have asthmatic features consisting of wheezing, airway hyper-responsiveness or atopy. The Global initiative for Asthma/Globalinitiative for chronic Obstructive Lung Disease committee recently labelled these patients as having asthma-COPD overlap syndrome or ACOS. ACOS also encompasses patients with asthma, ≥40 years of age, who have been cigarette smokers (more than 5–10 pack years) or have had significant biomass exposure, and demonstrate persistent airflow limitation defined as a post-bronchodilator forced expiratory volume in 1 second (FEV₁)/forced vital capacity of <70%. Data over the past 30 years indicate that patients with ACOS have greater burden of symptoms including dyspnea and cough and show higher risk of COPD exacerbations and hospitalizations than those with pure COPD or pure asthma. Patients with ACOS also have increased risk of rapid FEV₁ decline and COPD mortality. Paradoxically, experimental evidence to support therapeutic decisions in ACOS patients is lacking because traditionally, patients with ACOS have been systematically excluded from therapeutic COPD and asthma trials to maintain homogeneity of the study population. In this study, we summarize the current understanding of ACOS, focusing on definitions, epidemiology and patient prognosis.

Prevalence and Risk Factors of Chronic Obstructive Pulmonary Disease among Nonsmokers: Fifth Korea National Health and Nutrition Examination Survey (2010-2012)

OBJECTIVES

The purpose of this study was to determine the prevalence of COPD among non-smoking adults, and to investigate the risk factors that affect disease occurrence.

METHODS

The data from the 5th Korea national health and nutrition examination survey (KNHNES) has been used, and 5,489 non-smoking adults aged between 40 to 79 years with diagnosable FEV1/FVC were selected therefrom as the subjects of this study.

RESULTS

The prevalence of COPD in non-smokers was observed to be 6.9%. The development of the COPD showed statistically significant difference among groups; males showed about 2.54 times (95% CI: 1.410∼146.612) higher rates compared to females, subjects aged 70-79 showed about 3.08 times (95% CI: 1.823∼11.437) higher rates compared to those aged 40-49, subjects whose education level was elementary school or less showed about 5.36 times (95% CI: 1.341∼21.393) higher rates compared to those who are college or more, and subjects who are middle school showed about 4.72 times (95% CI: 1.374∼16.217) higher rates compared to the college or more.

CONCLUSION

It is confirmed that development of the COPD in non-smokers reach significance. For the prevention of the disease, there is a need to identify COPD-related risk factors in males and the elderly and provide appropriate nursing intervention, and to develop health-related education programs for those with low educational background to take in order to promote the improvement of lung health.

Differences in chronic obstructive pulmonary disease phenotypes between non-smokers and smokers

INTRODUCTION AND OBJECTIVES

Although tobacco smoking is a major risk factor for chronic obstructive pulmonary disease (COPD), more than one-fourth of COPD patients are non-smokers. In this cross-sectional study, the differences in COPD phenotypes between non-smokers and smokers in male subjects were investigated and were focused on structural lung changes using a quantitative assessment of computed tomography (CT) images.

METHODS

They divided male participants with COPD, from a Korean cohort near a cement plant, into non-smokers and smokers by a cutoff of a 5 pack-year smoking history. Clinical characteristics, including age, body mass index (BMI), spirometry results, history of biomass smoke exposure, and CT measurements, were compared between the two groups. Emphysema index (EI) and mean wall area percentage (MWA %) were used to evaluate the structural lung changes on volumetric CT scans.

RESULTS

The non-smoker group (n = 49) had younger patients and had a greater BMI than the smoker group (n = 113) (P < .05). Spirometry results, including post-bronchodilator forced expiratory volume in 1 s, were comparable between the two groups. More smokers had emphysema than non-smokers (EI 10.0 vs. 6.5, P < .001), but after accounting the potential confounders in model analysis, the difference was borderline significance (P = .051). In the subgroup of biomass smoke-exposed subjects, MWA% was significantly greater in smokers than in non-smokers (MWA 69.1 vs. 65.3, P = .03), while EI was not statistically different (EI 7.1 vs. 10.4, P = .52).

CONCLUSIONS

Non-smoker males with COPD were younger and had a greater BMI than the smokers. Tobacco smoke exposure seemed to be associated with an emphysema-predominant phenotype, while biomass smoke exposure exhibited a significant interaction with tobacco smoking in an airway-predominant phenotype.

The Association Between Bone Mineral Density and Airflow Limitation in a Cohort of Fit Elderly Women

PURPOSE

As studies examining the association between bone mineral density (BMD) and airflow limitation (AL) have produced conflicting results, the current one set out to analyze if and to what degree there are any correlations between these variables in a population of fit elderly women.

METHODS

One hundred and twenty-one non-smoking, fit and healthy women (age ≥ 65 years) underwent anthropometric assessment, laboratory testing (serum 25-hydroxy vitamin D, parathormone, and cytokine levels), pulmonary function testing (PFT), and dual-energy X-ray absorptiometry to evaluate BMD values of the lumbar and femoral regions.

RESULTS

A significant positive association was found between FEV₁/FVC ratio (Tiffeneau index), a sensitive index of AL, and lumbar and femoral BMD; a 10 % increase in the FEV₁/FVC ratio resulted in a significant increase of 0.025 g/cm² in the total hip (p = 0.05), 0.027 g/cm² in the femoral neck (p = 0.02), 0.028 g/cm² in the femoral trochanter (p = 0.01), and 0.047 g/cm² in the lumbar (p = 0.03) BMDs. Binary logistic analyses demonstrated more than a threefold higher risk of low BMD values for the lowest FEV₁/FVC quartile in the lumbar (OR 4.62, 95 % CI 1.48-14.40, p = 0.008), total hip (OR 4.09, 95 % CI 1.28-13.05, p = 0.02 for the second quartile), and femoral trochanter regions (OR 3.90, 95 % CI 1.25-12.20, p = 0.02 for the third quartile).

CONCLUSIONS

AL was associated with a higher risk of reduced BMD in healthy, fit elderly women.

Different forms of adiponectin reduce the apoptotic and damaging effect of cigarette smoke extract on human bronchial epithelial cells

Chronic obstructive pulmonary disease (COPD) is a common respiratory disease, in which adiponectin may serve an important role. The present study investigated the role of adiponectin in the apoptotic and damaging effect of cigarette smoke extract (CSE) on human bronchial epithelial cells (16HBECs). An MTT assay showed that CSE significantly inhibited the proliferation of 16HBECs (F=1808.88, P<0.01). The 16HBECs were treated with different concentrations of high molecular weight (HMW) adiponectin and globular domain (gAd) adiponectin and it was observed that HMW and gAd dose-dependently inhibited the expression of tumor necrosis factor (TNF)-α and interleukin (IL)-8, and the generation of 4-hydroxy-nonenal and reactive oxygen species (ROS) in 16HBECs, thereby blocking the upregulating effect of CSE on these factors. However, the inhibitory effect of gAd on TNF-α and IL-8 expression was stronger compared with that of HMW, but the suppressing effect of HMW on ROS production was superior compared with that of gAd. Further testing of apoptosis indicated that CSE and HMW promoted the apoptosis of 16HBECs. However, such effects of HMW declined with an increase in concentration. In contrast, gAd showed an inhibitory effect on apoptosis and inhibited the occurrence of CSE-induced apoptosis in a dose-dependent manner. Therefore, the present study demonstrated that different forms of adiponectin may have different mechanisms of action, suggesting that further exploration of their effects may open a new avenue for the treatment of COPD.

Impact of air pollution on the burden of chronic respiratory diseases in China: time for urgent action

In China, where air pollution has become a major threat to public health, public awareness of the detrimental effects of air pollution on respiratory health is increasing-particularly in relation to haze days. Air pollutant emission levels in China remain substantially higher than are those in developed countries. Moreover, industry, traffic, and household biomass combustion have become major sources of air pollutant emissions, with substantial spatial and temporal variations. In this Review, we focus on the major constituents of air pollutants and their impacts on chronic respiratory diseases. We highlight targets for interventions and recommendations for pollution reduction through industrial upgrading, vehicle and fuel renovation, improvements in public transportation, lowering of personal exposure, mitigation of the direct effects of air pollution through healthy city development, intervention at population-based level (systematic health education, intensive and individualised intervention, pre-emptive measures, and rehabilitation), and improvement in air quality. The implementation of a national environmental protection policy has become urgent.

Independent effect of prior exacerbation frequency and disease severity on the risk of future exacerbations of COPD: a retrospective cohort study

Few studies have researched the independent effect of COPD severity on the risk of future exacerbations adjusted by previous exacerbation frequency. We aimed to analyse the independent effect of COPD severity on the risk of exacerbations in the following year, and whether this effect was stronger or not than the effect of a previous history of exacerbations. We conducted a retrospective population-based cohort study including 900 patients with confirmed COPD. Exacerbation frequency was observed for the previous year and for the following year. Patients were defined as ‘Frequent Exacerbator’ (FE) phenotype if they suffered ⩾2 exacerbations in a year, and were categorised according to the severity of COPD (GOLD Grades 1–4). Odds ratios (ORs) were estimated by logistic regression adjusting for age, gender, smoking status, severity of COPD and being FE in the previous year. The main predictor of being FE among all grades of COPD severity was a history of frequent exacerbations in the previous year: adjusted OR 4.97; 95% confidence interval (CI) (3.54–6.97). COPD severity was associated with a higher risk of being FE: Crude OR GOLD Grade 4 3.86; 95% CI (1.50–9.93). However, this association diminished after adjusting for being FE in the previous year: adjusted OR 2.08; 95% CI (0.75–5.82). Our results support that a history of frequent exacerbations in the previous year is the most important independent predictor of exacerbations in the following year, also among the most severe COPD patients. Severity of COPD would be associated with a higher risk of exacerbations, but this effect would be partly determined by the exacerbations suffered in the previous year.

Global and regional estimates of COPD prevalence: Systematic review and meta-analysis

Background

The burden of chronic obstructive pulmonary disease (COPD) across many world regions is high. We aim to estimate COPD prevalence and number of disease cases for the years 1990 and 2010 across world regions based on the best available evidence in publicly accessible scientific databases.

Methods

We conducted a systematic search of Medline, EMBASE and Global Health for original, population–based studies providing spirometry–based prevalence rates of COPD across the world from January 1990 to December 2014. Random effects meta–analysis was conducted on extracted crude prevalence rates of COPD, with overall summaries of the meta–estimates (and confidence intervals) reported separately for World Health Organization (WHO) regions, the World Bank's income categories and settings (urban and rural). We developed a meta–regression epidemiological model that we used to estimate the prevalence of COPD in people aged 30 years or more.

Findings

Our search returned 37 472 publications. A total of 123 studies based on a spirometry–defined prevalence were retained for the review. From the meta–regression epidemiological model, we estimated about 227.3 million COPD cases in the year 1990 among people aged 30 years or more, corresponding to a global prevalence of 10.7% (95% confidence interval (CI) 7.3%–14.0%) in this age group. The number of COPD cases increased to 384 million in 2010, with a global prevalence of 11.7% (8.4%–15.0%). This increase of 68.9% was mainly driven by global demographic changes. Across WHO regions, the highest prevalence was estimated in the Americas (13.3% in 1990 and 15.2% in 2010), and the lowest in South East Asia (7.9% in 1990 and 9.7% in 2010). The percentage increase in COPD cases between 1990 and 2010 was the highest in the Eastern Mediterranean region (118.7%), followed by the African region (102.1%), while the European region recorded the lowest increase (22.5%). In 1990, we estimated about 120.9 million COPD cases among urban dwellers (prevalence of 13.2%) and 106.3 million cases among rural dwellers (prevalence of 8.8%). In 2010, there were more than 230 million COPD cases among urban dwellers (prevalence of 13.6%) and 153.7 million among rural dwellers (prevalence of 9.7%). The overall prevalence in men aged 30 years or more was 14.3% (95% CI 13.3%–15.3%) compared to 7.6% (95% CI 7.0%–8.2%) in women.

Conclusions

Our findings suggest a high and growing prevalence of COPD, both globally and regionally. There is a paucity of studies in Africa, South East Asia and the Eastern Mediterranean region. There is a need for governments, policy makers and international organizations to consider strengthening collaborations to address COPD globally.

Predictors of Hospitalized Exacerbations and Mortality in Chronic Obstructive Pulmonary Disease

BACKGROUND AND AIM

Exacerbations of chronic obstructive pulmonary disease (COPD) carry significant consequences for patients and are responsible for considerable health-care costs-particularly if hospitalization is required. Despite the importance of hospitalized exacerbations, relatively little is known about their determinants. This study aimed to analyze predictors of hospitalized exacerbations and mortality in COPD patients.

METHODS

This was a retrospective population-based cohort study. We selected 900 patients with confirmed COPD aged ≥35 years by simple random sampling among all COPD patients in Cantabria (northern Spain) on December 31, 2011. We defined moderate exacerbations as events that led a care provider to prescribe antibiotics or corticosteroids and severe exacerbations as exacerbations requiring hospital admission. We observed exacerbation frequency over the previous year (2011) and following year (2012). We categorized patients according to COPD severity based on forced expiratory volume in 1 second (Global Initiative for Chronic Obstructive Lung Disease [GOLD] grades 1-4). We estimated the odds ratios (ORs) by logistic regression, adjusting for age, sex, smoking status, COPD severity, and frequent exacerbator phenotype the previous year.

RESULTS

Of the patients, 16.4% had ≥1 severe exacerbations, varying from 9.3% in mild GOLD grade 1 to 44% in very severe COPD patients. A history of at least two prior severe exacerbations was positively associated with new severe exacerbations (adjusted OR, 6.73; 95% confidence interval [CI], 3.53-12.83) and mortality (adjusted OR, 7.63; 95%CI, 3.41-17.05). Older age and several comorbidities, such as heart failure and diabetes, were similarly associated.

CONCLUSIONS

Hospitalized exacerbations occurred with all grades of airflow limitation. A history of severe exacerbations was associated with new hospitalized exacerbations and mortality.

The Risk Factors and Characteristics of COPD Among Nonsmokers in Korea: An Analysis of KNHANES IV and V

PURPOSE

Chronic obstructive pulmonary disease (COPD) is increasing in prevalence and mortality. This study evaluated the prevalence, risk factors, characteristics, and health-related quality of life (HRQoL) of COPD among nonsmokers in Korea.

METHODS

This was a population-based cross-sectional study using data obtained from the Fourth and Fifth Korean National Health and Nutrition Examination Survey, which was conducted from 2007 to 2011.

RESULTS

A total of 15,063 participants completely answered the questionnaire and performed the spirometry. Among them, 59.6 % were nonsmokers and 40.4 % were smokers. The prevalence of nonsmoker COPD was 7.1 %. On multivariate analysis, age ≥65 years (OR, 2.93; 95 % CI, 2.44-3.51), male sex (OR, 2.98; 95 % CI, 2.40-3.71), living in rural area (OR, 1.26; 95 % CI, 1.05-1.51), lower body mass index (BMI) (<18.5 kg/m(2)) (OR, 3.00; 95 % CI, 1.78-5.01), self-reported asthma (OR, 2.72; 95 % CI, 2.05-3.60), and self-reported tuberculosis (OR, 4.73; 95 % CI, 3.63-6.17) showed a significantly higher risk of nonsmoker COPD. Analysis of nonsmoker and smoker COPD revealed that there are more females in nonsmoker COPD patients (73.9 vs. 6.9 %, P < 0.001). Nonsmoker COPD patients presented with impaired mobility, pain/discomfort, and anxiety/depression functions as well as a lower mean EuroQol Five-Dimension Questionnaire utility score, which showed HRQoL.

CONCLUSIONS

The burden of nonsmoker COPD was considerable. Older age, male sex, lower BMI, self-reported asthma, and self-reported tuberculosis were risk factors for nonsmoker COPD and there were differences between nonsmoker and smoker COPD in terms of sex, comorbidities, and HRQoL.

COPD in Nonsmokers: Reports from the Tunisian Population-Based Burden of Obstructive Lung Disease Study

BACKGROUND

It's currently well known that smoking and increasing age constitute the most important risk factors for chronic obstructive pulmonary disease (COPD). However, little is known about COPD among nonsmokers. The present study aimed to investigate prevalence, risk factors and the profiles of COPD among nonsmokers based on the Tunisian Burden of Obstructive Lung Disease (BOLD) study.

METHODS

807 adults aged 40 years+ were randomly selected from the general population. We collected information about history of respiratory disease, risk factors for COPD and quality of life. Post-bronchodilator spirometry was performed for assessment of COPD. COPD diagnostic was based on the post-bronchodilator FEV1/FVC ratio, according to the Global Initiative for Obstructive Lung Disease (GOLD) guidelines. The lower limit of normal (LLN) was determined as an alternative threshold for the FEV1/FVC ratio.

RESULTS AND CONCLUSIONS

Among 485 nonsmokers, 4.7% met the criteria for GOLD grade I and higher COPD. These proportions were similar even when the LLN was used as a threshold. None of the nonsmokers with COPD reported a previous doctor diagnosis of COPD compared to 7.1% of smokers. Nonsmokers accounted for 45.1% of the subjects fulfilling the GOLD spirometric criteria of COPD. Nonsmokers were predominately men and reported more asthma problems than obstructed smokers. Among nonsmokers significantly more symptoms and higher co-morbidity were found among those with COPD. Increasing age, male gender, occupational exposure, lower body mass index and a previous diagnosis of asthma are associated with increased risk for COPD in nonsmokers. This study confirms previous evidence that nonsmokers comprise a substantial proportion of individuals with COPD. Nonsmokers with COPD have a specific profile and should, thus, receive far greater attention to prevent and treat chronic airway obstruction.

Meta-analysis of the association between second-hand smoke exposure and ischaemic heart diseases, COPD and stroke

Background

Second-hand smoke (SHS) is the most important contaminant of indoor air in first world countries. The risks associated with SHS exposure are highly relevant, because many people are regularly, and usually involuntarily, exposed to SHS. This study aims to quantify the effects of SHS exposure. Therefore, its impact on ischaemic heart diseases (IHD), chronic obstructive pulmonary diseases (COPD) and stroke will be considered.

Methods

A systematic literature review was conducted to identify articles dealing with the association between SHS and the three outcomes IHD, COPD and stroke. Overall, 24 articles were included in a meta-analysis using a random effects model. Effect sizes stratified for sex and for both sexes combined were calculated.

Results

The synthesis of primary studies revealed significant effect sizes for the association between SHS exposure and all three outcomes. The highest RR for both sexes combined was found for COPD (RR = 1.66, 95 % CI: 1.38–2.00). The RR for both sexes combined was 1.35 (95 % CI: 1.22–1.50) for stroke and 1.27 (95 % CI: 1.10–1.48) for IHD. The risks were higher in women than in men for all three outcomes.

Conclusions

This is the first study to calculate effect sizes for the association between SHS exposure and the disease outcomes IHD, COPD, and stroke at once. Overall, the effect sizes are comparable with previous findings in meta-analyses and therefore assumed to be reliable. The results indicate the high relevance of public health campaigns and legislation to protect non-smokers from the adverse health effects attributable to SHS exposure.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-015-2489-4) contains supplementary material, which is available to authorized users.

Global and regional estimates of COPD prevalence: Systematic review and meta-analysis

BACKGROUND

The burden of chronic obstructive pulmonary disease (COPD) across many world regions is high. We aim to estimate COPD prevalence and number of disease cases for the years 1990 and 2010 across world regions based on the best available evidence in publicly accessible scientific databases.

METHODS

We conducted a systematic search of Medline, EMBASE and Global Health for original, population-based studies providing spirometry-based prevalence rates of COPD across the world from January 1990 to December 2014. Random effects meta-analysis was conducted on extracted crude prevalence rates of COPD, with overall summaries of the meta-estimates (and confidence intervals) reported separately for World Health Organization (WHO) regions, the World Bank's income categories and settings (urban and rural). We developed a meta-regression epidemiological model that we used to estimate the prevalence of COPD in people aged 30 years or more.

FINDINGS

Our search returned 37 472 publications. A total of 123 studies based on a spirometry-defined prevalence were retained for the review. From the meta-regression epidemiological model, we estimated about 227.3 million COPD cases in the year 1990 among people aged 30 years or more, corresponding to a global prevalence of 10.7% (95% confidence interval (CI) 7.3%-14.0%) in this age group. The number of COPD cases increased to 384 million in 2010, with a global prevalence of 11.7% (8.4%-15.0%). This increase of 68.9% was mainly driven by global demographic changes. Across WHO regions, the highest prevalence was estimated in the Americas (13.3% in 1990 and 15.2% in 2010), and the lowest in South East Asia (7.9% in 1990 and 9.7% in 2010). The percentage increase in COPD cases between 1990 and 2010 was the highest in the Eastern Mediterranean region (118.7%), followed by the African region (102.1%), while the European region recorded the lowest increase (22.5%). In 1990, we estimated about 120.9 million COPD cases among urban dwellers (prevalence of 13.2%) and 106.3 million cases among rural dwellers (prevalence of 8.8%). In 2010, there were more than 230 million COPD cases among urban dwellers (prevalence of 13.6%) and 153.7 million among rural dwellers (prevalence of 9.7%). The overall prevalence in men aged 30 years or more was 14.3% (95% CI 13.3%-15.3%) compared to 7.6% (95% CI 7.0%-8.2%) in women.

CONCLUSIONS

Our findings suggest a high and growing prevalence of COPD, both globally and regionally. There is a paucity of studies in Africa, South East Asia and the Eastern Mediterranean region. There is a need for governments, policy makers and international organizations to consider strengthening collaborations to address COPD globally.

Increased risk of chronic obstructive pulmonary disease among patients with Helicobacter pylori infection: a population-based cohort study

BACKGROUND

Increasing evidence suggests that Helicobacter pylori infection (HPI) may have extragastric manifestations, including the respiratory system. This study investigated the role of HPI in increasing the subsequent risk of chronic obstructive pulmonary disease (COPD) in a nationwide population.

METHODS

We conducted this retrospective cohort study using data from the Longitudinal Health Insurance Database, which is derived from the Taiwanese National Health Insurance Research Database. A total of 5941 adults who were newly diagnosed with HPI between 2005 and 2006 were selected. Healthy patients without HPI were selected from the general population and frequency matched as a ratio of 4:1, according to age, sex, and index years. Both cohorts were followed up from the index date to the end of 2011 to measure the incidence of COPD. Cox proportional hazard regression analysis was used to assess the hazard ratio (HR) of COPD between the HPI cohort and non-HPI cohorts.

RESULTS

The overall HR of COPD was 1.84 (95% confidence intervals = 1.57-2.17) for the HPI cohort, compared with the non-HPI cohort, after adjusting for age, sex, and comorbidities. Although the incidence of COPD was substantially higher in the elderly participants (age, ≥ 65 years) than that in younger participants, the highest HR (4.05, 95% confidence intervals = 1.39-11.8) of COPD was observed in the youngest (age, 20-49 years) participants.

CONCLUSION

In this study, the patients with HPI exhibited a significantly higher risk of COPD than those without HPI did.

Prevalence and risk factors of COPD among never-smokers in two areas of Sweden - Occupational exposure to gas, dust or fumes is an important risk factor

BACKGROUND

Although active tobacco smoking is the main risk factor for COPD, COPD is not uncommon also among never-smokers. Different study locations along with different spirometric definitions of COPD have historically yielded different prevalence estimates of the disease.

AIM

To study current prevalence and risk factors of COPD among never-smokers in two areas of Sweden.

METHODS

Data collected in 2008-2012 within the West Sweden Asthma Study and Obstructive Lung Disease in Northern Sweden Studies was pooled. The study population consisted of 1839 subjects who participated in spirometry and interviews. COPD was defined as post-bronchodilator a) FEV(1)/(F)VC < 0.7, b) FEV(1)/FVC < 0.7 and c) FEV(1)/FVC < lower limit of normal.

RESULTS

Of the 1839 subjects, 967 (52.6%) were never-smokers. Among the never-smoking subjects, the prevalence of COPD according to definitions a-c was 7.7%, 4.9% and 3.0%, respectively. The corresponding prevalence of GOLD grade ≥2 was 2.0%, 1.4% and 1.3%. No significant difference in prevalence between the two study areas was observed. In never-smokers, occupational exposure to gas, dust or fumes (GDF) was significantly associated with both COPD (OR 1.85, 95% CI 1.03-3.33), and GOLD ≥2 (OR 4.51, 1.72-11.9) according to definition a), after adjusting for age, educational level and exposure to passive smoking at work.

CONCLUSION

Depending on definition, prevalence of COPD among never-smokers was 3.0-7.7%, whereas GOLD ≥2 was present in 1.3-2.0%. Occupational exposure to GDF remained independently and significantly associated with COPD regardless of spirometric definition of the disease.

Asthma and COPD Overlap Syndrome (ACOS): A Systematic Review and Meta Analysis

Background

The combination of asthma and chronic obstructive pulmonary disease (COPD), or ACOS is a recently defined syndrome. The epidemiology of the condition is poorly described and previous research has suggested ACOS is associated with worse outcomes than either condition alone. We therefore decided to complete a systematic review of the published literature.

Methods

This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta- Analyses guidelines. A structured search was performed in the PubMed, Embase, and Medline databases up to Feb 2015 to identify studies reporting incidence, prevalence, health care utilization, morbidity, or mortality in COPD and asthma.

Results

A total of 19 studies were included in the present study. The pooled prevalence of overlap among COPD was 27% (95% CI: 0.16–0.38, p<0.0001) and 28% (95% CI: 0.09–0.47, p = 0.0032) in the population and hospital-based studies, respectively. We found no significant difference between ACOS and COPD in terms of gender, smoking status, lung function and 6mWD. However, in comparison to subject with only COPD, ACOS subjects were significantly younger, had higher BMI, healthcare utilization, and lower HRQoL.

Conclusion

ACOS is a common condition that exists in a substantial proportion of subjects with COPD. ACOS represents a distinct clinical phenotype with more frequent exacerbations, hospitalization, worse health-related quality of life, and higher healthcare costs than either disease alone. There is a critical need to better define the management and treatment of this syndrome.

Characteristics of COPD in never-smokers and ever-smokers in the general population: results from the CanCOLD study

BACKGROUND

There is limited data on the risk factors and phenotypical characteristics associated with spirometrically confirmed COPD in never-smokers in the general population.

AIMS

To compare the characteristics associated with COPD by gender and by severity of airway obstruction in never-smokers and in ever-smokers.

METHOD

We analysed the data from 5176 adults aged 40 years and older who participated in the initial cross-sectional phase of the population-based, prospective, multisite Canadian Cohort of Obstructive Lung Disease study. Never-smokers were defined as those with a lifetime exposure of <1/20 pack year. Logistic regressions were constructed to evaluate associations for 'mild' and 'moderate-severe' COPD defined by FEV1/FVC <5th centile (lower limits of normal). Analyses were performed using SAS V.9.1 (SAS Institute, Cary, North Carolina, USA).

RESULTS

The prevalence of COPD (FEV1/FVC<lower limits of normal) in never-smokers was 6.4%, constituting 27% of all COPD subjects. The common independent predictors of COPD in never-smokers and ever-smokers were older age, self reported asthma and lower education. In never-smokers a history of hospitalisation in childhood for respiratory illness was discriminative, while exposure to passive smoke and biomass fuel for heating were discriminative for women. COPD in never-smokers and ever-smokers was characterised by increased respiratory symptoms, 'respiratory exacerbation' events and increased residual volume/total lung capacity, but only smokers had reduced DLCO/Va and emphysema on chest CT scans.

CONCLUSIONS

The study confirmed the substantial burden of COPD among never-smokers, defined the common and gender-specific risk factors for COPD in never-smokers and provided early insight into potential phenotypical differences in COPD between lifelong never-smokers and ever-smokers.

TRIAL REGISTRATION NUMBER

NCT00920348 (ClinicalTrials.gov); study ID number: IRO-93326.

Novel aspects of pathogenesis and regeneration mechanisms in COPD

Chronic obstructive pulmonary disease (COPD), a major cause of death and morbidity worldwide, is characterized by expiratory airflow limitation that is not fully reversible, deregulated chronic inflammation, and emphysematous destruction of the lungs. Despite the fact that COPD is a steadily growing global healthcare problem, the conventional therapies remain palliative, and regenerative approaches for disease management are not available yet. We aim to provide an overview of key reviews, experimental, and clinical studies addressing lung emphysema development and repair mechanisms published in the past decade. Novel aspects discussed herein include integral revision of the literature focused on lung microflora changes in COPD, autoimmune component of the disease, and environmental risk factors other than cigarette smoke. The time span of studies on COPD, including emphysema, chronic bronchitis, and asthmatic bronchitis, covers almost 200 years, and several crucial mechanisms of COPD pathogenesis are described and studied. However, we still lack the holistic understanding of COPD development and the exact picture of the time-course and interplay of the events during stable, exacerbated, corticosteroid-treated COPD states, and transitions in-between. Several generally recognized mechanisms will be discussed shortly herein, ie, unregulated inflammation, proteolysis/antiproteolysis imbalance, and destroyed repair mechanisms, while novel topics such as deviated microbiota, air pollutants-related damage, and autoimmune process within the lung tissue will be discussed more extensively. Considerable influx of new data from the clinic, in vivo and in vitro studies stimulate to search for novel concise explanation and holistic understanding of COPD nowadays.

Study on risk factors and phenotypes of acute exacerbations of chronic obstructive pulmonary disease in Guangzhou, China-design and baseline characteristics

BACKGROUND

To describe a study design that focuses on risk factors and patterns of chronic obstructive pulmonary disease (COPD) exacerbations.

METHODS

A 2-year, single centre, observational study was conducted in Guangzhou in China. The study enrolled 318 subjects with COPD aged 40-79 years, stratified into different but equally sized groups according to global initiative for chronic obstructive lung disease (GOLD) stage (including Stage 0) and 86 lung healthy controls. An assessment each year was scheduled including questionnaires, lung function testing, Chest X-ray and blood collection. A sub-group, called sub-group X, consisting of 203 subjects with COPD and 51 lung healthy controls, was selected to answer a symptom questionnaire daily (EXACT-PRO) via a BlackBerry Personal Digital Assistant (PDA) device. Upon an alert that indicated a change in daily symptom pattern, the patients were contacted by the clinic to decide whether they had experienced an exacerbation and should have an extra visit within 24-48 hours. At an extra visit, nasal and throat swabs, induced sputum and blood were collected. Air pollution, temperature and humidity were also monitored daily. A subset of sub-group X, called sub-group M that consisted of 52 COPD patients and 15 healthy controls was dedicated to measure muscle strength and a dexa scan.

RESULTS

More than 78% of the enrolled patients completed the study successfully. There appeared a difference between the patient groups and the controls in gender, age, body mass index (BMI), forced expiratory volume in 1 second (FEV1), FEV1/FVC and smoking at baseline. In sub-group X 90 out of 203 (44.4%) selected COPD patients developed one or more exacerbations in the 2-year observation period. They were more severe COPD patients according to GOLD stage at study start. On average most exacerbations occurred in the month March and the least number of exacerbations occurred in October.

CONCLUSIONS

This study with the obtained patient dataset will allow a better insight in many aspects of exacerbations in COPD (e.g., the identification, the risk factors, phenotypes and the biomarkers).

The prevalence and patient characteristics of chronic obstructive pulmonary disease in non-smokers in Vietnam and Indonesia: An observational survey

BACKGROUND AND OBJECTIVE

An estimated 25-40% of patients with chronic obstructive pulmonary disease (COPD) have never smoked. We investigated the prevalence and patient characteristics of COPD in non-smokers from Vietnam and Indonesia.

METHODS

This population-based cross-sectional survey of participants from urban and rural Vietnam and Indonesia used a stratified multistage cluster sampling design, with sample and population weights applied to ensure representativeness. Participants were female or male (recruited in the ratio 2:1) non-smokers, 40 years or older and able to perform a spirometry test. Spirometry was performed at a single study visit. Other clinical information was collected via standardized questionnaires.

RESULTS

The 1506 evaluable participants were approximately equally distributed between Vietnam and Indonesia, and rural and urban areas. Overall prevalence of COPD was found to be 6.9% (95% confidence interval (CI): 5.7-8.3), with almost three times higher prevalence in men than women (12.9% (95% CI: 9.1-18.0) vs 4.4% (95% CI: 3.0-6.5)). We found higher rates of COPD in Vietnam than Indonesia (8.1% (95% CI: 5.8-11.3) vs 6.3% (95% CI: 4.8-8.3)), with a particularly high prevalence in urban Vietnam (11.1% (95% CI: 8.1-15.1)). Very few participants (6%) diagnosed to have COPD during the study had been previously diagnosed with COPD. Respiratory symptoms and lower health-related quality of life were more common in participants with COPD.

CONCLUSIONS

The prevalence of COPD in non-smoking individuals from rural and urban Vietnam and Indonesia was 6.9%, of which a significant proportion (94%) were previously undiagnosed.

Risk factors for chronic obstructive pulmonary disease among never-smokers in Korea

Background

Chronic obstructive pulmonary disease (COPD) patients include those who have never smoked. However, risk factors other than smoking in never-smokers have not been elucidated sufficiently. This study investigated the risk factors for COPD among never-smokers in Korea using population-based data.

Methods

The data were retrieved from the Korean National Health and Nutrition Survey IV conducted from 2007 to 2009. Among subjects aged 40 years or older who underwent appropriate pulmonary function tests, never-smokers not diagnosed with asthma and not showing a restrictive pattern on pulmonary function tests were enrolled. Risk factors of COPD in never-smokers were analyzed using logistic regression models.

Results

Among 24,871 participants in the representative Korean cohort, 3,473 never-smokers were enrolled. COPD patients accounted for 7.6% of the never-smokers. In the logistic regression analysis, low education status (odds ratio [OR]: 2.0; 95% confidence interval [CI]: 1.2–3.2), occupational exposure (OR: 2.6; 95% CI: 1.3–5.3), a history of tuberculosis (OR: 4.5; 95% CI: 2.3–8.7), bronchiectasis (OR: 6.0; 95% CI: 1.4–25.4), male sex (OR: 4.2; 95% CI: 2.6–6.7), advanced age (60–69 years vs 40–49 years; OR: 3.8; 95% CI: 2.0–7.0), and being underweight (body mass index <18.5 vs 18.0–24.9 kg/m²; OR: 3.1; 95% CI: 1.0–9.4) were associated with the development of COPD.

Conclusion

Low education status, manual labor, a history of tuberculosis and bronchiectasis, as well as male sex, advanced age and being underweight were risk factors for COPD in Korean never-smokers.

Relationship between haze and acute cardiovascular, cerebrovascular, and respiratory diseases in Beijing

Haze is an atmospheric phenomenon in which dry particulate pollutants obscure the sky. Haze has been associated with chronic diseases, but its relationship with acute diseases is less clear. We aimed to determine the association between haze and acute cardiovascular, cerebrovascular, and respiratory diseases, in order to determine the influence of haze on human health. We compared the number of cases of acute cardiovascular, cerebrovascular, and respiratory diseases in Beijing Emergency Center between 2006 and 2013, with haze data from Beijing Observatory. The relationship between the number of hazy days and the number of cases of the above types of diseases was analyzed using univariate analyses. Both the number of cases and the number of hazy days showed a rising trend. The average number of cases per day for all three diseases was higher on hazy days than on non-hazy days. There was a positive correlation between the number of hazy days and the number of cases, and this correlation showed a hysteretic quality. Haze has an influence on acute cardiovascular (CVDs), cerebrovascular (CBDs), and respiratory system (RSDs) diseases. Haze seems to have an additive effect, since the associations between haze and number of cases were stronger in the following month than in the preceding month. The increasing trend in the number of hazy days might worsen the problem of haze-related diseases.

Validation of a COPD screening questionnaire and establishment of diagnostic cut-points in a Japanese general population: the Hisayama study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is highly prevalent worldwide. COPD is a treatable disease and it is important to identify COPD subjects, highlighting the need for an efficient screening measure. Although the COPD screening questionnaire (COPD Population Screener, COPD-PS) was developed as a screening tool, its validity is not clear in population-based studies. This study determines the validity of the COPD-PS in the general Japanese population.

METHODS

All registered residents living in the town of Hisayama aged above 40 were solicited to participate in a health check-up in 2012. All subjects aged 40-79 without physician-diagnosed asthma or lung resection were recruited, and 2357 subjects with the COPD-PS recorded and valid spirometry measurements were analyzed. Persistent airflow obstruction (AO) was defined by post-bronchodilator FEV1/FVC < 0.7. The sensitivity and specificity of the COPD-PS score for identifying AO was assessed by logistic regression analysis.

RESULTS

The prevalence of AO in this population was 6.5%. The overall area under the receiver operating characteristic (ROC) curve for the continuous COPD-PS score was 0.748. A cut-point of 4-points is recommended, resulting in a sensitivity of 67.1% and specificity of 72.9% with an area under the ROC curve of 0.70. The positive predictive value was 14.6% and negative predictive value was 97.0%.

CONCLUSIONS

The COPD-PS appears to be an adequate measure for large scale screening of possible airflow obstruction requiring further testing with spirometry.

Distribution of clinical phenotypes in patients with chronic obstructive pulmonary disease caused by biomass and tobacco smoke

INTRODUCTION

Exposure to biomass smoke is a risk factor for chronic obstructive pulmonary disease (COPD). It is unknown whether COPD caused by biomass smoke has different characteristics to COPD caused by tobacco smoke.

OBJECTIVE

To determine clinical differences between these two types of the disease.

METHODS

Retrospective observational study of 499 patients with a diagnosis of COPD due to biomass or tobacco smoke. The clinical variables of both groups were compared.

RESULTS

There were 122 subjects (24.4%) in the biomass smoke group and 377 (75.5%) in the tobacco smoke group. In the tobacco group, the percentage of males was higher (91.2% vs 41.8%, P<.0001) and the age was lower (70.6 vs 76.2 years, P<.0001). Body mass index and FEV1% values were higher in the biomass group (29.4±5.7 vs 28.0±5.1, P=.01, and 55.6±15.6 vs 47.1±17.1, P<.0001, respectively). The mixed COPD-asthma phenotype was more common in the biomass group (21.3% vs 5%, P<.0001), although this difference disappeared when corrected for gender. The emphysema phenotype was more common in the tobacco group (45.9% vs 31.9%, P=.009). The prevalence of the chronic bronchitis and exacerbator phenotypes, the comorbidity burden and the rate of hospital admissions were the same in both groups.

CONCLUSION

Differences were observed between COPD caused by biomass and COPD caused by tobacco smoke, although these may be attributed in part to uneven gender distribution between the groups.

COPD in a nationally representative sample: sociodemographic factors and co-morbidity, diagnosis method, and healthcare utilization

INTRODUCTION

In 2011, the Centers for Disease Control and Prevention for the first time ever collected nationally representative prevalence data on chronic obstructive pulmonary disease (COPD), spirometry diagnosis, and healthcare utilization factors related to COPD. This research reports on that data and describes characteristics of adults with COPD who reported diagnosis by spirometry compared to those who did not report diagnosis by spirometry. Variables examined included basic elements of healthcare utilization such as emergency room visits, hospitalization or personal physician utilization.

METHODS

This is a cross-sectional study using novel data from the 2011 Behavioral Risk Factor Surveillance System COPD Module. Weighted multivariable logistic regression examined factors associated with (n = 13,484) and without spirometry (n = 3,131).

RESULTS

Spirometry to diagnose COPD was reported by 78% of adults and increased with age. In multivariable modeling, spirometry was more likely in: Black, non-Hispanic compared to white non-Hispanic; current and former compared to never smokers; adults with co-morbidity including asthma, depression, and cardiovascular disease; adults with a doctor; and those who had been to emergency room/hospital for COPD. Those less likely to receive a spirometry were: Hispanic and reported exercise in the past 30 days.

CONCLUSIONS

This study identified that adults diagnosed with COPD without a spirometry tended to be Hispanic, younger, healthier, and had less utilization of medical resources. This study is a first step in understanding the potential impact of COPD diagnosis made without spirometry.

Prevalence and correlates of airflow obstruction in ∼317,000 never-smokers in China

In China, the burden of chronic obstructive disease (COPD) is high in never-smokers but little is known about its causes in this group. We analysed data on 287 000 female and 30 000 male never-smokers aged 30-79 years from 10 regions in China, who participated in the China Kadoorie Biobank baseline survey (2004-2008). Prevalence of airflow obstruction (AFO) (pre-bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) <0.7 and below the lower limit of normal (LLN)) was estimated, by age and region. Cross-sectional associations of AFO (FEV1/FVC <0.7), adjusted for confounding, were examined. AFO prevalence defined as FEV1/FVC <0.7 was 4.0% in females and 5.1% in males (mean ages 51 and 54 years, respectively). AFO prevalence defined as FEV1/FVC Collapse

Key Words Collapse

MESH Headings

• Adult
• Aged
• Air Pollution, Indoor
• Asthma/diagnosis
• Asthma/epidemiology
• Body Mass Index
• China
• Cooking
• Cross-Sectional Studies
• Female
• Forced Expiratory Volume
• Humans
• Male
• Middle Aged
• Odds Ratio
• Prevalence
• Pulmonary Disease, Chronic Obstructive/diagnosis
• Pulmonary Disease, Chronic Obstructive/epidemiology
• Respiration
• Smoking
• Spirometry
• Surveys and Questionnaires
• Vital Capacity

Collapse

Grants

• Wellcome Trust
• MC_U137686851 Medical Research Council

Collapse

Affiliation(s)

Margaret Smith Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), University of Oxford, Oxford, UK
Liming Li Chinese Academy of Medical Sciences, Beijing School of Public Health, Peking University Health Sciences Center, Beijing
Mareli Augustyn Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), University of Oxford, Oxford, UK
Om Kurmi Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), University of Oxford, Oxford, UK
Junshi Chen China National Center for Food Safety Risk Assessment, Beijing
Rory Collins Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), University of Oxford, Oxford, UK
Yu Guo Chinese Academy of Medical Sciences, Beijing
Yabin Han Tongxiang Center for Disease Control, Tongxiang
Jingxin Qin Liuzhou Center for Disease Control, Liuzhou
Guanqun Xu Suzhou Center for Disease Control, Suzhou
Jian Wang Pengzhou Center for Disease Control, Pengzhou
Zheng Bian Chinese Academy of Medical Sciences, Beijing
Gang Zhou Henan Center for Disease Control, Zhengzhou, China
Richard Peto Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), University of Oxford, Oxford, UK
Zhengming Chen Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), University of Oxford, Oxford, UK

Collapse

Chronic obstructive pulmonary disease prevalence among nonsmokers by occupation in the United States

OBJECTIVE

To examine the prevalence of chronic obstructive pulmonary disease (COPD) among nonsmokers by occupation in the United States.

METHODS

The 1997 to 2004 National Health Interview Survey data for working adults aged 25 years or more were used to estimate the COPD prevalence and to examine change in COPD prevalence between 1997 to 2000 and 2001 to 2004 by occupational groups.

RESULTS

During 1997 to 2004, COPD prevalence was 2.8%. The COPD prevalence was highest in financial records processing (4.6%) occupations. There was a slight increase in COPD prevalence during the two survey periods from 2.8% during 1997 to 2000 compared with 2.9% during 2001 to 2004.

CONCLUSIONS

No significant changes in the COPD prevalence between the two periods were found. Nevertheless, the elevated COPD prevalence in certain occupational groups suggests that other risk factors play a role in developing COPD.

Lung function and incidence of chronic obstructive pulmonary disease after improved cooking fuels and kitchen ventilation: a 9-year prospective cohort study

BACKGROUND

Biomass smoke is associated with the risk of chronic obstructive pulmonary disease (COPD), but few studies have elaborated approaches to reduce the risk of COPD from biomass burning. The purpose of this study was to determine whether improved cooking fuels and ventilation have effects on pulmonary function and the incidence of COPD.

METHODS AND FINDINGS

A 9-y prospective cohort study was conducted among 996 eligible participants aged at least 40 y from November 1, 2002, through November 30, 2011, in 12 villages in southern China. Interventions were implemented starting in 2002 to improve kitchen ventilation (by providing support and instruction for improving biomass stoves or installing exhaust fans) and to promote the use of clean fuels (i.e., biogas) instead of biomass for cooking (by providing support and instruction for installing household biogas digesters); questionnaire interviews and spirometry tests were performed in 2005, 2008, and 2011. That the interventions improved air quality was confirmed via measurements of indoor air pollutants (i.e., SO₂, CO, CO₂, NO₂, and particulate matter with an aerodynamic diameter of 10 µm or less) in a randomly selected subset of the participants' homes. Annual declines in lung function and COPD incidence were compared between those who took up one, both, or neither of the interventions. Use of clean fuels and improved ventilation were associated with a reduced decline in forced expiratory volume in 1 s (FEV₁): decline in FEV₁ was reduced by 12 ml/y (95% CI, 4 to 20 ml/y) and 13 ml/y (95% CI, 4 to 23 ml/y) in those who used clean fuels and improved ventilation, respectively, compared to those who took up neither intervention, after adjustment for confounders. The combined improvements of use of clean fuels and improved ventilation had the greatest favorable effects on the decline in FEV₁, with a slowing of 16 ml/y (95% CI, 9 to 23 ml/y). The longer the duration of improved fuel use and ventilation, the greater the benefits in slowing the decline of FEV₁ (p<0.05). The reduction in the risk of COPD was unequivocal after the fuel and ventilation improvements, with an odds ratio of 0.28 (95% CI, 0.11 to 0.73) for both improvements.

CONCLUSIONS

Replacing biomass with biogas for cooking and improving kitchen ventilation are associated with a reduced decline in FEV₁ and risk of COPD.

TRIAL REGISTRATION

Chinese Clinical Trial Register ChiCTR-OCH-12002398.

Cooking oil fumes and lung cancer: a review of the literature in the context of the U.S. population

There is growing evidence that exposure to cooking oil fumes (COF) is linked to lung cancer. Existing literature on this risk was reviewed, specifically as it may relate to potentially at-risk populations such as Chinese immigrants and restaurant workers in the United States. Studies were identified by searching the NCBI database with key terms. All studies that examined the significance, prevalence, and/or mechanism(s) of the association between COF exposure and cancer (all types) were included. A majority of epidemiologic studies found associations between lung cancer and COF exposure. All studies that examined the mechanisms underlying the risk found evidence for mutagenic and/or carcinogenic compounds in COF extract and/or molecular mechanisms for COF-induced DNA damage or carcinogenesis. The evidence reviewed underscores the need to thoroughly investigate the association among at-risk groups in the United States, as well as to develop and assess concrete interventions to reduce these risks.

Prevalence of COPD and tobacco smoking in Tunisia--results from the BOLD study

In Tunisia, there is a paucity of population-based data on Chronic Obstructive Pulmonary Disease (COPD) prevalence. To address this problem, we estimated the prevalence of COPD following the Burden of Lung Disease Initiative. We surveyed 807 adults aged 40+ years and have collected information on respiratory history and symptoms, risk factors for COPD and quality of life. Post-bronchodilator spirometry was performed and COPD and its stages were defined according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. Six hundred and sixty one (661) subjects were included in the final analysis. The prevalence of GOLD Stage I and II or higher COPD were 7.8% and 4.2%, respectively (Lower Limit of Normal modified stage I and II or higher COPD prevalence were 5.3% and 3.8%, respectively). COPD was more common in subjects aged 70+ years and in those with a BMI < 20 kg/m2. Prevalence of stage I+ COPD was 2.3% in <10 pack years smoked and 16.1% in 20+ pack years smoked. Only 3.5% of participants reported doctor-diagnosed COPD. In this Tunisian population, the prevalence of COPD is higher than reported before and higher than self-reported doctor-diagnosed COPD. In subjects with COPD, age is a much more powerful predictor of lung function than smoking.

Peak flow as a predictor of cause-specific mortality in China: results from a 15-year prospective study of ∼170 000 men

Background Forced expiratory volume in one second (FEV1) is inversely associated with mortality in Western populations, but few studies have assessed the associations of peak expiratory flow (PEF) with subsequent cause-specific mortality, or have used populations in developing countries, including China, for such assessments.

Methods A prospective cohort study followed ∼170 000 Chinese men ranging in age from 40–69 years at baseline (1990–1991) for 15 years. In the study, height-adjusted PEF (h-PEF), which was uncorrelated with height, was calculated by dividing PEF by height. Hazard ratios (HR) for cause-specific mortality and h-PEF, adjusted for age, area of residence, smoking, and education, were calculated through Cox regression analyses.

Results Of the original study population, 7068 men died from respiratory causes (non-neoplastic) and 22 490 died from other causes (including 1591 from lung cancer, 5469 from other cancers, and 10 460 from cardiovascular disease) before reaching the age of 85 years. Respiratory mortality was strongly and inversely associated with h-PEF. For h-PEF ≥ 250 L/min, the association was log-linear, with a hazard ratio (HR) of 1.29 (95% CI: 1.25–1.34) per 100 L/min reduction in h-PEF. The association was stronger but not log-linear for lower values of h-PEF. Mortality from combined other causes was also inversely associated with h-PEF, and the association was log-linear for all values of h-PEF, declining with follow-up, with HRs per 100 L/min reduction in h-PEF of 1.13 (1.10–1.15), 1.08 (1.06–1.11), and 1.06 (1.03–1.08) in three consecutive 5-year follow-up periods. Specifically, lower values of h-PEF were associated with higher mortality from cardiovascular disease and lung cancer, but not from other cancers.

Conclusions A lower value of h-PEF was associated with increased mortality from respiratory and other causes, including lung cancer and cardiovascular disease, but its associations with the other causes of death declined across the follow-up period.

Chronic obstructive pulmonary disease in non-smokers: a case-comparison study

BACKGROUND

COPD is often regarded as a smoker's disease. In fact, up to 50% of COPD could be attributable to other causes. Relatively little is known about COPD among nonsmokers, and this group is usually excluded from studies of COPD.

METHODS

In this cross-sectional case-comparison study, smokers and nonsmokers aged over 45 with COPD (post-bronchodilator FEV1 ≤ 70% predicted, FEV1/FVC ratio < 0.7) were recruited from specialist outpatient clinics and from primary care. Subjects completed a questionnaire and interview, and underwent spirometry, venesection, exhaled nitric oxide (ENO) measurement, allergen skinprick testing, formal lung function testing and high resolution CT.

RESULTS

48 nonsmokers and 45 smokers participated. Asthma was nearly universal among nonsmokers and was the commonest identifiable cause of COPD in that group. Nonsmokers also exhibited a high prevalence of objective eosinophilic inflammation (raised ENO and eosinophil counts, positive skinprick tests). Smokers had more severe airflow obstruction, but respiratory symptom prevalences were similar between groups. Nonsmokers reported greater lifetime burdens of respiratory disease. Nonsmokers' HRCT results showed functional small airways disease, with no significant emphysema in any subject. Previously undiagnosed bronchiectasis was common in both groups (31% and 42%).

CONCLUSIONS

Asthma is a very common cause of COPD among nonsmokers. Radiological bronchiectasis is common in COPD; the clinical significance of this finding is unclear.

Supporting smoking cessation in chronic obstructive pulmonary disease with behavioral intervention: a randomized controlled trial

BACKGROUND

Cigarette smoking is the major risk factor for chronic obstructive pulmonary disease (COPD). But a fewer smoking cessation measures were conducted in communities for smokers with COPD in China. The aim of our study was to assess the preventive effects of behavioral interventions for smoking cessation and potential impact factors in smokers with COPD in China.

METHODS

In a randomised controlled smoking cessation trial 3562 patients with COPD who were current smoker were allocated to intervention group received behavioral intervention and control group received the usual care for two years. The primary efficacy endpoint was the complete and continuous abstinence from smoking from the beginning of month 24 to the end of month 30. Participants were followed up at month 48.

RESULTS

Continuous smoking abstinence rates from month 24 to 30 were significantly higher in participants receiving behavioral intervention than in those receiving usual care (46.4% vs 3.4%, p < 0.001). Continuous abstinence rates from months 24 to 36 (45.8% vs 4.0%) and months 24 to 48 (44.3% vs 5.1%) were also higher in participants receiving behavioral intervention than in those control group. Family members or family physicians/nurses smoking were first identified to influence smoking cessation.

CONCLUSIONS

Behavioral intervention doubled the smoking cessation rate in patients with COPD and was complied well by the general practitioners. The family members and family physicians/nurses smoking were the main risk factors for smoking cessation.

TRIAL REGISTRATION

Chinese Clinical Trials Registration (ChiCTR-TRC-12001958).

Respiratory health in home and leisure pursuits

Many home-based and leisure activities can generate hazardous respirable exposures. Routine domestic activities and a variety of hobbies, avocations, and leisure pursuits have been associated with a spectrum of respiratory tract disorders. Indoor environments present a special risk for high-intensity exposures and adverse health effects. There are important knowledge gaps regarding the prevalence of specific health hazards within and across communities, exposure-response effects, population and individual susceptibilities, best management strategies, the adverse health effects of mixed exposures, and long-term clinical outcomes following exposures. The home environment presents special health risks that should be part of the health assessment.

A discriminant function model as an alternative method to spirometry for COPD screening in primary care settings in China

OBJECTIVE

COPD is often underdiagnosed in a primary care setting where the spirometry is unavailable. This study was aimed to develop a simple, economical and applicable model for COPD screening in those settings.

METHODS

First we established a discriminant function model based on Bayes' Rule by stepwise discriminant analysis, using the data from 243 COPD patients and 112 non-COPD subjects from our COPD survey in urban and rural communities and local primary care settings in Guangdong Province, China. We then used this model to discriminate COPD in additional 150 subjects (50 non-COPD and 100 COPD ones) who had been recruited by the same methods as used to have established the model. All participants completed pre- and post-bronchodilator spirometry and questionnaires. COPD was diagnosed according to the Global Initiative for Chronic Obstructive Lung Disease criteria. The sensitivity and specificity of the discriminant function model was assessed.

RESULTS

THE ESTABLISHED DISCRIMINANT FUNCTION MODEL INCLUDED NINE VARIABLES: age, gender, smoking index, body mass index, occupational exposure, living environment, wheezing, cough and dyspnoea. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, accuracy and error rate of the function model to discriminate COPD were 89.00%, 82.00%, 4.94, 0.13, 86.66% and 13.34%, respectively. The accuracy and Kappa value of the function model to predict COPD stages were 70% and 0.61 (95% CI, 0.50 to 0.71).

CONCLUSIONS

This discriminant function model may be used for COPD screening in primary care settings in China as an alternative option instead of spirometry.

Non-smoking-related chronic obstructive pulmonary disease: a neglected entity?

Chronic obstructive pulmonary disease (COPD) is an increasing cause of morbidity and mortality worldwide, and it has been strongly correlated to tobacco smoking. While a number of studies have concentrated on smokers only, recent published data demonstrate that at least one fourth of patients with COPD are non-smokers, and that the burden of COPD in non-smokers is also higher than previously believed. Risk factors of COPD in non-smokers may include genetic factors, long-standing asthma, outdoor air pollution (from traffic and other sources), environmental smoke exposure (ETS), biomass smoke, occupational exposure, diet, recurrent respiratory infection in early childhood, tuberculosis and so on. In Asian region, indoor/outdoor air pollution and poor socioeconomic status may play important roles in the pathogenesis of non-smoking-related COPD. The prevalence of COPD among never smokers varies widely across nations. Such a variation may arise from several aspects, including study design, definition of COPD, diagnostic criteria, age and gender distribution of the studied population, local risk factors and socioeconomic status. More investigations and efforts are required to elucidate the involved factors and their shared contributions to non-smoking-related COPD so as to achieve better estimation and reduction of the burden of this neglected entity worldwide.

Secondhand smoke exposure predicted COPD and other tobacco-related mortality in a 17-year cohort study in China

BACKGROUND

Prospective evidence on the association between secondhand smoke (SHS) and COPD and ischemic stroke is scarce.

METHODS

We prospectively examined the relationship between SHS and major tobacco-related deaths, particularly COPD and stroke, in 910 Chinese (439 men, 471 women) who never smoked from a 17-year follow-up study in Xi’an, China. SHS exposure was defi ned as exposure to another person’s tobacco smoke at home or in the workplace.

RESULTS

At baseline among the 910 subjects, 44.2% were exposed to SHS at home, 52.9% in the workplace, and 67.1% at home, work, or both. From March 1, 1994, to July 1, 2011, 249 (150 men,99 women) died within 14,016 person-years. Those who were exposed to SHS had increased mortality due to coronary heart disease (adjusted relative risk [RR], 2.15; 95% CI, 1.00-4.61), ischemic stroke (RR, 2.88; 95% CI, 1.10-7.55), lung cancer (RR, 2.00; 95% CI, 0.62-6.40), COPD (RR, 2.30;95% CI, 1.06-5.00), and all causes (RR, 1.72; 95% CI, 1.29-2.20), with significant dose-response relationships between cumulative SHS exposure at home and work and the increased risk of cause-specific and total mortality (P for linear trend ranged from .045 to , .001).

CONCLUSIONS

This study shows dose-response relationships between SHS and major tobacco-related mortality and provides new evidence to support causation for COPD and ischemic stroke.

Correlates of COPD and chronic bronchitis in nonsmokers: data from a cross-sectional study

Purpose

Our objective was to assess the prevalence of chronic bronchitis and chronic obstructive pulmonary disease (COPD) and their correlates among a Lebanese nonsmoker group.

Material and methods

A cross-sectional study was conducted between October 2009 and September 2010, using a multistage cluster sample throughout Lebanon including Lebanese residents aged 40 years and above with no exclusion criteria. Pre- and postbronchodilator spirometry measurements were performed and carbon monoxide level was measured in exhaled air. COPD was defined and classified according to the Global Initiative for Chronic Obstructive Lung Disease guidelines or according to the lower limit of normal (forced expiratory volume in 1 second/forced vital capacity postbronchodilator < 5th percentile of the healthy population having the same age and sex). Chronic bronchitis was defined by the declaration of morning cough and expectorations for more than 3 months a year over more than 2 years in individuals with normal spirometry.

Results

Out of 2201 individuals, 732 were never-smokers: 25 (3.4%) of them had COPD, and 86 (11.75%) fulfilled the definition of chronic bronchitis. Correlates of COPD included a childhood respiratory disease, house heated by diesel, and older age. On the other hand, correlates of chronic bronchitis included childhood respiratory diseases, living in southern Lebanon versus other regions, heating home by gas, older age, number of smokers at work, and lower height.

Conclusion

A substantial percentage of the nonsmoking population may exhibit chronic bronchitis or COPD. The significant correlates mentioned above should be taken into consideration in order to reduce the risk of developing such chronic and debilitating respiratory diseases.