Environmental exposures and systemic hypertension are risk factors for decline in lung function

Endoscopic reflux esophagitis and decline in pulmonary function in nonsmokers: A retrospective cohort study

BACKGROUND

The association between reflux esophagitis and pulmonary function remains controversial. Thus, evaluating the relationship between endoscopic reflux esophagitis and changes in pulmonary function over time in a nonsmoking population is an important clinical issue.

METHODS

In this single-center retrospective cohort study, a medical examination database at Kameda Medical Center Makuhari was employed to identify nonsmokers who underwent upper gastrointestinal endoscopy and spirometry in 2010 and were followed up in 2015. Gastroenterologists carefully double-checked the diagnosis of reflux esophagitis. Multiple linear regression analyses were performed to compare the decline in the percentage of predicted vital capacity (%VC), forced vital capacity (%FVC), and forced expiratory volume in 1 s (%FEV1) between participants with reflux esophagitis and those without. Furthermore, using multivariable logistic regression analyses, we evaluated the factors associated with rapid decline in %VC, %FVC, and %FEV1, which is defined as a decrease of >10% in each parameter over the 5-year observation period.

RESULTS

We identified 3098 eligible subjects, including 72 and 44 participants who had a Los Angeles classification grade A and B-C (severe) reflux esophagitis in 2010, respectively. The decline in %VC was significantly larger in the participants with severe reflux esophagitis than in the control subjects (standardized coefficient, -0.037; 95% confidence interval, -0.071 to -0.004). Moreover, reflux esophagitis was significantly associated with a rapid decline in %VC and %FVC but not in %FEV1 (P for trend: 0.009, 0.009, and 0.276, respectively).

CONCLUSIONS

Severe reflux esophagitis among nonsmokers had clinical disadvantages in terms of a decline in %VC.

The Impact of Different Smoking Behavior on Pulmonary Function and Pulmonary Hypertension Among Chinese Male Patients with Chronic Obstructive Pulmonary Disease

Purpose

Cigarette smoking is the most recognized risk factor of chronic obstructive pulmonary disease (COPD) in China. However, there are no studies analyzing the impact of different smoking behaviors on pulmonary function and pulmonary hypertension (PH) among Chinese male patients with COPD.

Patients and Methods

Chinese male smokers with COPD performed pulmonary function tests. Clinical characteristics, smoking behavior features, spirometry and echocardiographic results were compared between the two groups stratified by initial smoking age (18 years old) or complicated PH.

Results

The early-smoking group had more respiratory symptoms, more severe smoking behavior, worse pulmonary function with lower FEV1%pre (38.5% vs 70.2%) and FEV1/FVC% (47.5% vs 63.8%), and higher systolic pulmonary artery pressure (sPAP: 38.6 vs 33.9 mmHg) than the late-smoking group. Initiating smoking before adulthood was an independently contributing factor of ventilatory dysfunction and Global Initiative for Obstructive Lung Disease (GOLD) stage escalation. It also had a significant interaction with long smoking duration (≥30 years), characterized by markedly decreased lung volumes (VC%pre: 64.0% vs 84.5%), impaired diffusing capacity (DLCO%pre: 58.0% vs 76.8%) and severe emphysema (RV/TLC%pre: 145.2% vs 130.2%). COPD patients complicated with PH exhibited worse ventilatory function (FEV1%pre: 43.2% vs 56.2%), impaired diffusion capacity (DLCO%pre: 56.7% vs 77.1%) and decreased lung volume (VC%pre: 67.67% vs 75.38%). Both severe smoking behaviors and impaired pulmonary function had close correlations with sPAP.

Conclusion

The early-smoking group exhibited predominantly ventilation dysfunction and had complex interactions with long smoking duration to further affect lung volume and diffusion capacity. Different smoking behaviors influenced variations of pulmonary dysfunction and comorbid PH in patients with COPD.

Association Between Decreased Renal Function and Pulmonary Function Decline in Community-dwelling Adults

BACKGROUND/AIM

Emerging evidence suggests that there is a close relationship between the human lung and kidney. This study evaluated whether decreased renal function was associated with accelerated pulmonary function decline in a large-scale community-based cohort.

PATIENTS AND METHODS

A total of 10,028 subjects of the prospective Ansung-Ansan cohort were eligible for the longitudinal analysis of changes in pulmonary function associated with decreased renal function (glomerular filtration rate <60 ml/min/1.73 m2). Logistic regression analysis was performed to evaluate factors associated with decreased baseline renal function, and a linear mixed model compared changes in pulmonary function in participants with and without decreased renal function after propensity score matching (PSM).

RESULTS

At baseline, subjects with and without decreased renal function showed distinct characteristics, and the factors associated with decreased renal function were age, baseline forced vital capacity, hypertension, and white blood cell (WBC) count. A 1:4 PSM of age, sex, body mass index, and smoking status showed that the proportion of those with hypertension and the WBC count differed between the patients with decreased and normal renal function. In the PSM population, those with decreased renal function had a greater decline in forced expiratory volume in the first second (FEV1) than those without (p=0.0402); however, these differences were not found to be evident when hypertension and WBC count were further matched (p=0.0807).

CONCLUSION

The results of our study demonstrated that decreased renal function was not directly associated with the rapid decline in pulmonary function in a community-based general population setting.

Clinical relevance of lung function trajectory clusters in middle-aged and older adults

Background

The determinants and health outcomes of lung function trajectories in adults among the general population are poorly understood. We aimed to identify and characterise clusters of lung function trajectories in adults aged ≥45 years.

Methods

Gaussian finite-mixture modelling was applied to baseline and annualised change of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio z-scores in participants of the Rotterdam Study, a prospective population-based cohort study, with repeated spirometry (n=3884; mean±sd age 64.7±8.9 years). Longitudinal outcomes were all-cause mortality, respiratory outcomes (symptoms, COPD (FEV1/FVC <0.7 in absence of asthma), preserved ratio impaired spirometry (PRISm; FEV1/FVC ≥0.7 and FEV1 or FVC <80%)), smoking cessation and weight changes. Independent risk factors, including genetics, were identified by multiple logistic regression.

Results

We identified eight trajectory clusters, with the reference group having persistently normal spirometry (prevalence 42.8%). Three clusters showed higher mortality, adjusted for confounders: 1) the persistently low FEV1 cluster (prevalence 6.8%, hazard ratio (HR) 1.71, 95% CI 1.37-2.13); 2) rapid FEV1 decliners (prevalence 4.6%, HR 1.48, 95% CI 1.10-1.99); and 3) FVC decliners (prevalence 3.7%, HR 1.49, 95% CI 1.09-2.03). In contrast, FVC improvers (prevalence 6.7%, HR 0.61, 95% CI 0.41-0.90) and persistently high FEV1 (prevalence 29.2%, HR 0.82, 95% CI 0.69-0.98) were protective trajectory clusters. Clusters were characterised by differences in genetic predisposition (polygenic scores of FEV1 and FEV1/FVC), demographics, cigarette smoking, respiratory symptoms (chronic cough, wheezing and dyspnoea), cardiovascular factors (body mass index, hypertension and heart failure) and serum C-reactive protein levels. Frailty, weight changes and the development of respiratory symptoms, COPD and PRISm were significantly associated with trajectory clusters.

Conclusions

This study reveals clinically relevant lung function trajectory clusters in older adults of the general population.

Global Burden of Chronic Obstructive Pulmonary Disease Through 2050

Importance

Chronic obstructive pulmonary disease (COPD) is a respiratory condition that is associated with significant health and economic burden worldwide. Previous studies assessed the global current-day prevalence of COPD, but to better facilitate resource planning and intervention development, long-term projections are needed.

Objective

To assess the global burden of COPD through 2050, considering COPD risk factors.

Design, Setting, and Participants

In this modeling study, historical data on COPD prevalence was extracted from a recent meta-analysis on 2019 global COPD prevalence, and 2010 to 2018 historical prevalence was estimated using random-effects meta-analytical models. COPD risk factor data were obtained from the Global Burden of Disease database.

Main Outcomes and Measures

To project global COPD prevalence to 2050, generalized additive models were developed, including smoking prevalence, indoor and outdoor air pollution, and development indices as predictors, and stratified by age, sex, and World Bank region.

Results

The models estimated that the number of COPD cases globally among those aged 25 years and older will increase by 23% from 2020 to 2050, approaching 600 million patients with COPD globally by 2050. Growth in the burden of COPD was projected to be the largest among women and in low- and middle-income regions. The number of female cases was projected to increase by 47.1% (vs a 9.4% increase for males), and the number of cases in low- and middle-income regions was expected to be more than double that of high-income regions by 2050.

Conclusions and Relevance

In this modeling study of future COPD burden, projections indicated that COPD would continue to affect hundreds of millions of people globally, with disproportionate growth among females and in low-middle income regions through 2050. Further research, prevention, and advocacy are needed to address these issues so that adequate preparation and resource allocation can take place.

Angiotensin Receptor Blockers Restore Skeletal Muscle in Patients with Chronic Obstructive Pulmonary Disease

BACKGROUND

Age-related muscle decline, called sarcopenia, and hypertension are commonly observed in patients with chronic obstructive pulmonary disease (COPD). Angiotensin receptor blockers (ARBs) are common antihypertensive medications with muscle protective effects. However, the anti-sarcopenic potential and associated mechanisms of ARBs in hypertensive patients with COPD are unknown.

OBJECTIVES

We aimed to investigate the potential contribution of neuromuscular junction (NMJ) stability as a driving mechanism of ARBs-induced muscle protection.

METHODS

We categorized 236 patients with COPD into normotensive (n = 79) and hypertensive, based on treatment with ARB (n = 82), and other antihypertensive drugs (n = 75). Hypertensive patients with COPD were evaluated at two time points one year apart. Handgrip strength (HGS), body composition, short physical performance battery (SPPB), and plasma c-terminal agrin fragment-22 (CAF22) as a marker of NMJ degradation were measured.

RESULTS

Patients with COPD exhibited reduced HGS and SPPB scores, and higher levels of CAF22 than controls, regardless of hypertension status. ARBs treatment improved HGS and gait speed and reduced plasma CAF22 levels in hypertensive patients with COPD (all p <0.05). ARBs also prevented the decline in SPPB components, including maintaining balance, gait speed, and the ability to rise from a chair in hypertensive patients with COPD (all p <0.05). We also found dynamic associations of plasma CAF22 with HGS, gait speed, and SPPB scores in hypertensive patients with COPD.

CONCLUSIONS

Altogether, ARB treatment preserves skeletal muscle health and functional capacity in hypertensive patients with COPD by reducing plasma CAF22 and possibly repairing NMJs.

Hypertensive disorders of pregnancy and risk of asthma and chronic obstructive pulmonary disease: a prospective cohort study

Background

Hypertensive disorders of pregnancy (HDPs) have been associated with respiratory dysfunction during pregnancy and postpartum. In this study, we explored the associations between HDPs (gestational hypertension and preeclampsia) and the risk of incident asthma and chronic obstructive pulmonary disease (COPD) during adulthood and the potential mediating role of chronic hypertension.

Methods

We included parous nurses in the Nurses' Health Study II reporting a pregnancy lasting no less than 6 months. The associations between HDPs and asthma and COPD were estimated using Cox proportional hazards models with adjustment for confounders.

Findings

We included 73,807 nurses [92.5% (68,246 of 73,807) White] in asthma analyses and 79,843 [92.4% (73,746 of 79,843) White] in COPD analyses, whose mean (SD, range) age, at baseline, were both 34.8 (4.7, 25.0-44.0) years. During 24 years of follow-up, we identified 2663 incident cases of asthma and 537 COPD. Compared with nurses without HDPs, nurses reporting HDPs had an increased HR for incident asthma and COPD of 1.22 (95% CI 1.10-1.36) and 1.39 (95% CI 1.11-1.74), respectively. The risk of asthma was similar when gestational hypertension and preeclampsia were assessed separately [HR = 1.25 (95% CI 1.08-1.43) and 1.24 (95% CI 1.11-1.38), respectively]. However, only nurses with preeclampsia had a higher risk of COPD (HR = 1.41, 95% CI 1.11-1.78). Mediation analyses estimated that chronic hypertension explained 18.6% (95% CI 8.9-35.0%) and 10.7% (95% CI 2.9-32.4%) of the associations between HDPs and asthma and COPD, respectively.

Interpretation

HDPs may serve as useful markers of increased susceptibility to chronic respiratory diseases during adulthood.

Funding

The National Institutes of Health grants.

Comparison of the lower limit of normal to the fixed ratio method for the diagnosis of airflow obstruction at high altitudes: a large cross-sectional survey of subjects living between 3000-4700 m above sea level

BACKGROUND

There is no general agreement on the preferential use of a fixed ratio (FR) of forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) < 0.7 vs. the lower limit of normal (LLN) of FEV₁/FVC to define airflow obstruction. Determining the impact of these different cut-off levels in people living at high altitudes has not been studied. We assessed the prevalence of airflow obstruction and its clinical characteristics in residents living at high altitude using a fixed ratio and the LLN of FEV₁/FVC according to Global Lung Initiative 2012 (GLI) reference values.

METHODS

Using a multistage stratified sampling method, 3702 participants (aged ≥ 15 years) living at an altitude of 3000-4700 m in Tibet were included.

RESULTS

11.4% and 7.7% of participants had airflow obstruction according to GLI-LLN and a fixed FEV₁/FVC cut-off value, respectively. The participants in the FR-/LLN+ group were younger, predominantly female, more frequently exposed to household air pollution, and had a higher proportion of chronic obstructive pulmonary disease assessment test scores ≥ 10 than those in the FR-/LLN- group. They also had a significantly lower FEV₁ and a higher frequency of small airway dysfunction. Compared with the participants of the FR+/LLN+ group, those in the FR-/LLN+ group showed no significant difference in the risk factors for airflow obstruction and respiratory symptoms, but had a lower prevalence of small airway dysfunction.

CONCLUSIONS

Defining airflow obstruction according to LLN, instead of using an FR, identified younger individuals with more frequent clinical symptoms of airflow obstruction and small airway dysfunction.

Development and validation of nomogram including high altitude as a risk factor for COPD: A cross-sectional study based on Gansu population

Background

Chronic Obstructive Pulmonary Disease (COPD) is a common and harmful disease that requires an effective tool to early screen high-risk individuals. Gansu has unique environments and customs, leading to the different prevalence and etiology of COPD from other regions. The association between altitude and COPD once attracted epidemiologists' attention. However, the prevalence in Gansu and the role of altitude are still unclarified.

Methods

In Gansu, a multistage stratified cluster sampling procedure was utilized to select a representative sample aged 40 years or older. The questionnaire and spirometry examination were implemented to collect participants' information. The diagnosis and assessment of COPD were identified by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criterion, while post-bronchodilator FEV₁/FVC < LLN was for sensitivity analysis. Furthermore, the effect of high altitude on COPD was evaluated by the logistic regression model after propensity score matching (PSM). Finally, the participants were randomly divided into training and validation sets. The training set was used to screen the relative factors and construct a nomogram which was further assessed by the receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA) in the two sets.

Results

There were 2,486 eligible participants in the final analysis, of which 1,584 lived in low altitudes and 902 lived in high altitudes. Based on the GOLD criterion, the crude and standardized prevalences in Gansu were 20.4% (18.7-22.0) and 19.7% (17.9-21.6). After PSM, the logistic regression model indicated that high altitude increased COPD risk [PSM OR: 1.516 (1.162-1.978)]. Altitude, age, sex, history of tuberculosis, coal as fuel, and smoking status were reserved for developing a nomogram that demonstrated excellent discrimination, calibration, and clinical benefit in the two sets.

Conclusions

COPD has become a serious public health problem in Gansu. High altitude is a risk factor for COPD. The nomogram has satisfactory efficiency in screening high-risk individuals.

Investigation and Analysis of Risk Factors and Psychological Status of Chronic Obstructive Pulmonary Disease in Permanent Residents Aged 40 or Older in Hongyuan County, Aba Prefecture, Sichuan Province

Background

COPD is an important public health problem worldwide, and there is a lack of epidemiological data on COPD in high-altitude areas in Sichuan province. Thus, we aimed to investigate the prevalence, risk factors and psychological status of COPD in Hongyuan County, Aba Prefecture, Sichuan Province, which is located at an average altitude of 3507 meters.

Methods

The 40 years old or greater permanent residents of Hongyuan County were selected by random sampling method, and the lung function test and questionnaires were conducted to determine the disease situation of COPD. The prevalence of COPD was compared among different factors of investigation, and multivariate logistic regression analysis was used for different factors to determine the independent influencing factors of COPD disease.

Results

A total of 456 permanent residents aged 40 years or older in Hongyuan County, 436 qualified for quality control, among which 53 cases confirmed COPD, the total prevalence was 12.16%, among which the prevalence was 14.55% for men and it was 8.07% for women. There were significant differences in different gender, ethnicity, age, smoking status, smoking years, educational level, heating style, history of tuberculosis, and prevalence of BMI (P <0.05). Binary logistic regression analysis showed that age ≥60 years (OR = 2.810, 95% CI: 1.0457.557), Han Nationality (OR: 3.238, 95% CI: 1.290-8.127), the heating method including biofuels (OR: 18.119, 95% CI: 4.140-79.303) and coals (OR: 6.973, 95% CI: 1.856-26.200), medical history of pulmonary tuberculosis (OR: 2.670, 95% CI: 1.278-5.578), the education level including junior high school (OR: 3.336, 95% CI: 1.2259.075), high school and above (OR: 5.910, 95% CI: 1.796-19.450), and smoking (OR: 10.774, 95% CI: 3.622-32.051) were independent risk factors for COPD disease. The prevalence of anxiety was 16.98%, and the prevalence of depression was 13.2%.

Conclusion

The prevalence of COPD in Hongyuan County was higher than the national level; age, ethnic group, education, smoking, heating method, and history of tuberculosis are the independent influencing factors of COPD in Hongyuan County. The prevalence of anxiety and depression is low.

Influence of cardiovascular risk burden on pulmonary function trajectory: role of physical and social activities

The impact of cardiovascular risk burden on long-term trajectories of pulmonary function (PF) remains unclear. We examined the association of cardiovascular risk burden assessed by Framingham general cardiovascular risk score (FGCRS) with PF decline and explored whether cardiovascular diseases (CVD), physical and social activities play a role in the association. Within the Rush Memory and Aging Project, 1,442 participants (mean age:79.83) were followed up to 22 years. FGCRS at baseline was calculated and categorized into tertiles. Composite PF was measured annually based on peak expiratory flow, forced expiratory volume in one second, and forced vital capacity. We found that the highest FGCRS was associated with faster PF decline (β: -0.013, 95% CI: -0.023 to -0.003) compared with the lowest FGCRS. There were significant interactions between higher FGCRS and low level of physical/social activity (β: -0.014, 95% CI: -0.026 to -0.003)/(β: -0.020, 95% CI:-0.031 to -0.009) or CVD(β: -0.023, 95% CI:-0.034 to -0.011) compared to the low FGCRS with high level of physical/social activity or without CVD (P-interaction<0.05). Our results suggest that higher cardiovascular risk burden is associated with a faster PF decline, especially among people with CVD. High level of physical activity and social activity appears to mitigate this association.

Prevalence of hypertension and its relationship with altitude in highland areas: a systematic review and meta-analysis

This systematic review and meta-analysis synthesized the pooled prevalence of hypertension at high altitudes and explored its correlation with altitude using studies published in Chinese and English from database inception to February 2021. A systematic literature search was conducted among bibliographic databases (PubMed, Embase, and Web of Science) and three Chinese databases (CNKI, VIP, and Wanfang data) to identify eligible studies. A random-effects model was used to calculate the overall pooled prevalence of hypertension. The I² statistic was used to assess heterogeneity across studies. Random-effects meta-regression was conducted to investigate covariates that may have influenced between-study heterogeneity. The pooled prevalence of hypertension among the general population in high-altitude areas was 33.0% (95% CI: 29.0-38.0%), with high between-study heterogeneity (I² = 99.4%, P < 0.01). Subgroup analyses showed the pooled prevalence of hypertension in Tibetan individuals was significantly higher than that in non-Tibetan individuals living in the Himalayas and Pamir Mountains (41% vs. 18%). A trend toward an increase in the prevalence of hypertension was found with every 100-m increase in elevation (coefficient: 0.012, 95% CI: -0.001 to 0.025, P = 0.069) only in Tibetan individuals. In addition, in these individuals, we found an increase in mean diastolic BP with each 100-m increase in altitude (coefficient: 0.763, 95% CI: 0.122-1.403, P = 0.025). Our meta-analysis suggests that the pooled prevalence of hypertension among the general population in high-altitude areas is 33.0%. Subjects of Tibetan ethnicity were more prone to developing hypertension at high altitudes. However, a very weak relationship between altitude and the prevalence of hypertension was found only in Tibetan individuals.

Peru - Progress in health and sciences in 200 years of independence

Peru celebrates 200 years of independence in 2021. Over this period of independent life, and despite the turbulent socio-political scenarios, from internal armed conflict to economic crisis to political instability over the last 40 years, Peru has experienced major changes on its epidemiological and population health profile. Major advancements in maternal and child health as well as in communicable diseases have been achieved in recent decades, and today Peru faces an increasing burden of non-communicable diseases including mental health conditions. In terms of the configuration of the public health system, Peru has also strived to secure country-wide optimal health care, struggling in particular to improve primary health care and intercultural services. The science and technology infrastructure has also evolved, although the need for substantial investments remains if advancing science is to be a national priority. Climate change will also bring significant challenges to population health given Peru's geographical and microclimates diversity. Looking back over the 200-years of independence, we present a summary of key advances in selected health-related fields, thus serving as the basis for reflections on pending agendas and future challenges, in order to look forward to ensuring the future health and wellbeing of the Peruvian population.

Resumen translated abstract

El Perú cumple 200 años de independencia en 2021. Durante estos dos siglos de vida independiente, junto con periodos sociales y políticos turbulentos, incluyendo un conflicto armado interno, hiperinflación y la inestabilidad política de los últimos 40 años, el Perú ha experimentado importantes cambios en su perfil epidemiológico con repercusiones directas en la salud de la población. En las últimas décadas, los indicadores de salud materno-infantil y de las enfermedades transmisibles muestran mejoría importante, pero el país se enfrenta de manera simultánea a una carga cada vez mayor de enfermedades no transmisibles y de salud mental. En cuanto a los sistemas de salud pública, se han realizado esfuerzos por aumentar la cobertura y calidad de la atención de salud en todo el país, apostándose en particular por mejorar la atención primaria. La ciencia y tecnología relacionadas con la salud también han mejorado, aunque si se quiere que la ciencia sea una prioridad nacional, son necesarias inversiones sustanciales. El cambio climático traerá importantes desafíos para la salud de la población, dada la diversidad geográfica y de microclimas del país. Para conmemorar los 200 años de vida independiente del Perú, presentamos un resumen de avances clave en diversas áreas y temas relacionados con la salud. Este repaso sirve como base para reflexionar sobre agendas y desafíos pendientes y futuros, con el fin de asegurar la salud y el bienestar de la población peruana en las próximas décadas.

Black Carbon Content in Airway Macrophages is Associated with Reduced CD80 Expression and Increased Exacerbations in Former Smokers With COPD

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by recurrent exacerbations. Macrophages play a critical role in immune response and tissue repair in COPD. Airway macrophages (AM) are exposed to environmental exposures which are retained in the cytoplasmic material. Both biomass and particulate matter have been linked to higher AM black carbon. It is unknown if AM black carbon is associated with COPD morbidity and macrophage phenotype.

METHODS

Former smokers with COPD were enrolled and sputum induction was performed to obtain airway macrophages. Macrophages underwent black carbon quantification and flow cytometry phenotyping. Health information was obtained the same day as sputum induction and prospective exacerbations were assessed by monthly telephone calls.

RESULTS

We studied 30 former smokers with COPD who had a mean age of 67 years and mean forced expiratory volume in 1 second (FEV1)% predicted of 60.8%. Higher AM black carbon content was associated with increased total exacerbations and severe exacerbations and reduced CD80 expression.

CONCLUSION

AM black carbon association with respiratory morbidity is largely unexplored and this is the first study to identify association with prospective exacerbations. Macrophages expressed reduced CD80, a surface marker providing costimulatory signals required for development of antigen-specific immune responses. Our findings suggest that reduced CD80 expression is the pathophysiologic mechanism for the association of AM black carbon content and increased exacerbations. Therefore, beyond solely serving as a marker for increased exposures, AM black carbon content may be a predictor of future exacerbations given a macrophage less equipped to respond to an acute infectious exposure.

Prevalence of chronic obstructive pulmonary disease at high altitude: a systematic review and meta-analysis

Background and objective

Recently, several studies have investigated the prevalence of chronic obstructive pulmonary disease (COPD) at high altitude (>1,500 m). However, much remains to be understood about the correlation between altitude and COPD. We aimed to summarize the prevalence of COPD at high-altitudes and find out if altitude could be a risk factor for COPD.

Methods

We searched PubMed/Medline, Cochrane Library, Web of Science, SCOPUS, OVID, Chinese Biomedical Literature Database (CBM) and Embase databases from inception to April 30th, 2019, with no language restriction. We used STATA 14.0 to analyze the extracted data. A random-effect model was used to calculate the combined OR and 95% CI. Heterogeneity was assessed by the I² statistic versus P-value. We performed a subgroup analysis to analyze possible sources of heterogeneity. The Egger’s test and the Begg’s test were used to assess any publication bias.

Results

We retrieved 4,574 studies from seven databases and finally included 10 studies (54,578 participants). Males ranged from 18.8% to 49.3% and the population who smoked ranged from 3.3% to 53.3%. The overall prevalence of COPD at high-altitude was 10.0% (95% CI [0.08–0.12], P < 0.001). In a subgroup analysis, based on different regions, the results showed that the prevalence in Asia was higher than that in Europe and America. Seven studies compared the relationship between the prevalence of COPD at high-altitudes and the lowlands. The results showed that altitude was not an independent risk factor for the prevalence of COPD (OR_adj = 1.18, 95% CI [0.85–1.62], P = 0.321). There was no publication bias among the studies.

Conclusions

Our study found a higher prevalence of COPD at high-altitudes than those from average data. However, altitude was not found to be an independent risk factor for developing COPD (PROSPERO Identifier: CRD42019135012).

High COPD prevalence at high altitude: does household air pollution play a role?

Studies comparing chronic obstructive pulmonary disease (COPD) prevalence across altitudes report conflicting results. However, household air pollution (HAP), a major COPD risk factor, was mostly not accounted for in previous analyses and never objectively measured. We aimed to compare the prevalence of COPD and its risk factors between low-resource highlands and lowlands, with a particular focus on objectively measured HAP.We conducted a population-based, observational study in a highland (∼2050 m above sea level) and a lowland (∼750 m above sea level) setting in rural Kyrgyzstan. We performed spirometry in randomly selected households, measured indoor particulate matter with an aerodynamic diameter <2.5 µm (PM2.5) and administered a questionnaire on other COPD risk factors. Descriptive statistics and multivariable logistic regressions were used for analyses.We included 392 participants: 199 highlanders and 193 lowlanders. COPD was more prevalent among highlanders (36.7% versus 10.4%; p<0.001). Their average PM2.5 exposure was also higher (290.0 versus 72.0 µg·m-3; p<0.001). In addition to high PM2.5 exposure (OR 3.174, 95% CI 1.061-9.493), the altitude setting (OR 3.406, 95% CI 1.483-7.825), pack-years of smoking (OR 1.037, 95% CI 1.005-1.070) and age (OR 1.058, 95% CI 1.037-1.079) also contributed to a higher COPD prevalence among highlanders.COPD prevalence and HAP were highest in the highlands, and were independently associated. Preventive interventions seem warranted in these low-resource, highland settings. With this study being one of the first spirometry-based prevalence studies in Central Asia, generalisability needs to be assessed.

Decreased lung function is associated with risk of developing non-alcoholic fatty liver disease: A longitudinal cohort study

BACKGROUND

Decreased lung function is associated with non-alcoholic fatty liver disease (NAFLD), based on linking mechanisms such as insulin resistance and systemic inflammation However, its association with the risk of developing NAFLD is unclear. Our aim was to investigate whether baseline lung function is associated with incident NAFLD in middle-aged healthy Koreans.

METHODS

A cohort study of 96,104 subjects (mean age: 35.7 years) without NAFLD were followed up from 2002 to 2015. NAFLD was diagnosed by ultrasound after the exclusion of other possible causes of liver diseases. Baseline percent predicted forced expiratory volume in one second (FEV1%) and forced vital capacity (FVC%) were categorized in quartiles. Adjusted hazard ratios (aHR) and 95% confidence intervals (CIs) (using the highest quartile as reference) were calculated for incident NAFLD at follow-up, controlling for covariates and potential confounders.

RESULTS

During 579,714.5 person-years of follow-up, 24,450 participants developed NAFLD (incidence rate, 42.2 per 1,000 person-years). The mean follow-up period was 5.9±3.4 years. Regardless of smoking history, the risk for incident NAFLD increased with decreasing quartiles of FEV1 (%) and FVC (%) in a dose-response manner (p for trend<0.001). In never smokers, the aHRs (95% CIs) for incident NAFLD were 1.15 (1.08-1.21), 1.11 (1.05-1.18), and 1.08 (1.02-1.14) in quartiles 1-3 for FEV1 (%) and 1.12 (1.06-1.18), 1.11 (1.05-1.18), and 1.09 (1.03-1.15) in quartiles 1-3 for FVC (%), compared with the highest quartile reference. Similar inverse association was present in smoke-exposed subjects (aHR for incident NAFLD were 1.14, 1.21, 1.13 and 1.17, 1.11, 1.09 across FEV1(%) and FVC(%) quartile in increasing order, respectively).

CONCLUSIONS

Reduced lung function was a risk factor for incident NAFLD in a large middle-aged Korean cohort with over half a million person-years of follow-up.