The association between cadmium exposure and the risk of chronic obstructive pulmonary disease: A systematic review and meta-analysis

According to the World Health Organization, chronic obstructive pulmonary disease (COPD) was one of the top ten causes of death worldwide in 2019. The ratio of forced expiratory volume in the first second to forced vital capacity (FEV1/FVC) provides a useful indicator for the diagnosis of COPD. Existing data have demonstrated that cadmium (Cd) exposure is associated with COPD. However, data concerning the incidence and progression of cadmium-induced COPD is inconsistent. To explore the relationship between cadmium exposure and the risk of COPD in humans, through January 12, 2023, we conducted a thorough search of the PubMed, Cochrane, Web of Science, Embase and Scopus databases for relevant material. In this study, a meta-analysis was conducted to evaluate the association between cadmium and COPD. This meta-analysis indicated that exposure to cadmium (per 1 μg/L increase) was associated with reduced FEV1/FVC (% change = -47.54%, 95% CI: -54.99% to -40.09%). Subgroup analysis showed that the combined effect estimates were significantly higher in the COPD patient group (% change = -54.66%, 95% CI: -83.32% to -26.00%) than in the general population (% change = -52.11%, 95%CI: -60.53% to -43.70%). Therefore, we conclude that cadmium exposure is associated with reduced FEV1/FVC, which suggests a risk for COPD.

Association between 25-hydroxy vitamin D and lung function (FEV1, FVC, FEV1/FVC) in children and adults with asthma: A systematic review

Asthma is a chronic respiratory disease that poses significant individual, social, financial and healthcare burdens. Physicians and researchers have recommended 25-hydroxy vitamin D supplementation, in combination with prescribed medication, as a potential means of reducing asthma severity. This systematic review focuses on the association between 25-hydroxy vitamin D levels and lung function in both children and adults with asthma. We identified published work by searching MEDLINE via PubMed, using regular search terms related to 25-hydroxy vitamin D and asthma. Fourteen studies were screened out of 643 eligible citations from MEDLINE research that involved 65 children and 951 adults. A strong positive association was observed in four studies, whereas five showed a moderate association, and two had no correlation. The majority of studies found a negative correlation between 25-hydroxy vitamin D deficiency and mild, uncontrolled and partly controlled asthma. 25-hydroxy vitamin D 25 OH values were below 20 ng/ml in the majority of studies, and those with uncontrolled severe asthma showed the lowest values.

Efficacy and safety of tiotropium bromide inhalation in symptomatic patients with chronic obstructive pulmonary disease: A multicenter, prospective, and observational study

OBJECTIVES

Treatment guidelines have recommended tiotropium bromide inhalation (TBI), a long-acting muscarinic antagonist, for chronic obstructive pulmonary disease (COPD); however, its efficacy in symptomatic Chinese patients with COPD remains uninvestigated.

METHODS

This multicenter, prospective, observational study enrolled patients with COPD assessment test (CAT) scores exceeding 10 points from 19 hospitals spread across China. All patients received TBI and underwent follow-up for 3 months. The demographic and clinical information were assessed.

RESULTS

The final analysis included 378 patients. The forced expiratory volume in 1 s (FEV₁) and FEV₁/forced vital capacity (FVC) of all participants improved markedly after 3 months of treatment (FEV₁: mean 1.33 L versus 1.61 L, P < 0.001; FEV₁/FVC: mean 0.53 versus 0.62, P < 0.001). The mean CAT scores decreased from 26.56 to 16.28 (P < 0.001). Patients classified into group D based on the Global Initiative for COPD guidelines showed greater improvement in FEV₁ and FEV₁/FVC than that in patients in group B. The proportion of patients with acute exacerbations also declined from 28.6% in the first month to 4.2% in the third month.

CONCLUSION

TBI for 3 months could effectively and safely attenuate symptoms and airflow obstruction in symptomatic Chinese patients with COPD.

Effect of Smoking on Lung Function Decline in a Retrospective Study of a Health Examination Population in Chinese Males

Objective

China has established a goal of reducing adult smoking prevalence from 27.7% to 20% by 2030. Understanding the possible ongoing impairment in lung function in smokers, is critically important to encourage the populations to change their smoking behavior.

Methods

A total of 14,273 males joined the health examination at Huadong Sanatorium from Jan 2012 to Dec 2019 were included. In cross-sectional analysis, we used multiple linear regression to evaluate the association between baseline lung function and smoking status. Then, 3,558 males who received ≥2 spirometry exams were analyzed in longitudinal study. Annual lung function decline was compared using mixed linear models adjusted for confounders.

Results

In cross-sectional analysis, compared with never-smokers, decreases of -133.56 mL (95% CI: -167.27, -99.85) and -51.44 mL (-69.62, -33.26) in FEV₁, -1.48% (-1.94, -1.02) and -1.29% (-1.53, -1.04) in FEV₁/FVC were observed in former and current smokers. In longitudinal analysis, significant declines were observed in FEV₁ [5.04 (2.30, 7.78) mL] and FEV₁/FVC [0.09 (0.05, 0.13) %] in current smokers but not observed in former smokers after adjustment. Participants with long duration of smoking cessation had decelerate lung function than short duration. The annual decline rate of current smokers with high smoking intensity (≥30 cigarettes per day) was 13.80 and 14.17 times greater than that of never-smokers in FEV₁ and FVC. Thus, early smoking cessation can slow down lung function decline trend for current smokers.

Conclusions

The harms of current smoking on lung function emphasize the necessity of smoking cessation, especially for those with comorbidities.

Human Umbilical Cord Mesenchymal Stromal Cell Treatment of Severe COVID-19 Patients: A 3-Month Follow-Up Study Following Hospital Discharge

Previously, we demonstrated the therapeutic effects of human umbilical cord mesenchymal stromal cells (hUC-MSCs) in severe coronavirus disease 2019 (COVID-19) patients. In this 3-month follow-up study, we examined discharged patients who had received hUC-MSC therapy to assess the safety of this therapy and the health-related quality of life (HRQL) of these patients. The follow-up cohort consisted of 28 discharged severe COVID-19 patients who received either the standard treatment (the control group) or the standard treatment plus hUC-MSC therapy. We examined liver function, kidney function, pulmonary function, coagulation, tumor markers, and vision. We also conducted electrocardiography (ECG) analysis, let the patients answer the St. George's Respiratory Questionnaire (SGRQ), and performed computed tomography (CT) imaging for assessing the lung changes. No obvious adverse effects were observed in the hUC-MSC group after 3 months. Measurements of blood routine index, C-reactive protein and procalcitonin, liver and kidney function, coagulation, ECG, tumor markers, and vision were almost within the normal ranges in both the treatment and control groups. Forced expiratory volumes in 1 s (FEV1) (% of predicted) were 71.88% ± 8.46% and 59.45% ± 27.45% in the hUC-MSC and control groups (P < 0.01), respectively, and FEV1/forced vital capacity (FEV1/FVC) ratios were 79.95% ± 8.00% and 58.97% ± 19.16% in the hUC-MSC and control groups, respectively (P < 0.05). SGRQ scores were lower in the hUC-MSC group than in the control group (15.25 ± 3.69 vs. 31.9 ± 8.78, P < 0.05). The rate of wheezing in the hUC-MSC group was also significantly lower than that in the control group (37.5% vs. 75%, P < 0.05). There were no significant differences in CT scores between the two groups (0.60 ± 0.88 vs. 1.00 ± 1.31, P = 0.917). Overall, the intravenous transplantation of hUC-MSCs accelerated partial pulmonary function recovery and improved HRQL, indicating relative safety and preliminary efficacy of this treatment for patients with severe COVID-19.

The associations between dietary pattern of chronic obstructive pulmonary disease patients and depression: a cross-sectional study

Background

Chronic obstructive pulmonary disease (COPD) is a common lung disease during middle age which one of its complications is depression. Depression is considered one of the major causes of severe disability worldwide. One of the factors that affect the severity and incidence of this disease is a lifestyle, especially dietary pattern. On the other hand, some studies showed the relationship between dietary patterns and depression. The present study aims to investigate the dietary patterns of people with chronic obstructive pulmonary disease and its association with depression.

Methods

The present cross-sectional study was performed on 220 patients (mean ± SD age = 54.58 ± 5.08) with chronic obstructive pulmonary disease (56.6% men, 43.4% women) from Tabriz, Iran. Questionnaires of general information, food frequency, Beck depression and physical activity were completed. The dominant dietary patterns were determined by factor analysis, and their relationship with depression was discussed by regression analysis.

Results

Three dominant dietary patterns were identified as healthy, unhealthy, and mixed dietary patterns. An inverse relationship was found between healthy and mixed dietary patterns with depression. There is no meaningful connection between unhealthy dietary patterns and depression. Depression had a significant inverse relationship with physical activity. There was no relationship between dietary patterns and Forced Expiratory Volume for 1 s (FEV1) and Forced Vital Capacity (FVC) criteria. A positive and significant relationship was observed between mixed dietary patterns with FEV1/FVC.

Conclusion

Inverse relationships exist between healthy dietary patterns and depression in patients with COPD, and improves the function of the lungs. Further studies are needed to show the exact relationship between diet and COPD depression.

Improved pulmonary function test (PFT) after 1 one year of Sublingual Immunotherapy (SLIT) in unison with pharmacotherapy in mild allergic asthmatics

BACKGROUND

Allergen immunotherapy (AIT) is a promising treatment for allergic disease that induces immunological tolerance through the administration of specific allergens. The study of AIT is in its early stage and its clinical effects are not well elucidated. The present study was aimed at determining the effect of AIT on pulmonary function and serum variables of mild allergic asthma patients.

METHODS

A total of 80 patients with mild allergic asthma were recruited for the study. Allergen Specific Immunotherapy was administered in the form of Sublingual Immunotherapy and consisted of a build up phase followed by a maintenance phase (six months each respectively). Total serum IgE and vitamin D levels were quantified by ELISA. The percent eosinophill count was determined by cell analyzers. Pulmonary function test was performed at the baseline and after the end of study period. Subjective symptom score was recorded in the form of asthma control questionnaire score.

RESULTS

There was a significant increase in the pre FEV1% and pre FEV1/FVC post AIT administration. A significant decrease in the total serum IgE was found post AIT. A decrease in Asthma control Questionnaire (ACQ) scores indicated an improvement in clinical symptoms. Besides there was a significant effect on ICS discontinuation after AIT.

CONCLUSION

The study supports SLIT as an effective treatment for Immunomodulation in mild allergic asthmatics besides it gives us significant information regarding the safety and efficacy of SLIT in such patients.

Lung Development Genes and Adult Lung Function

Rationale: Poor lung health in adult life may occur partly through suboptimal growth and development, as suggested by epidemiological evidence pointing to early life risk factors.

Objectives: To systematically investigate the effects of lung development genes on adult lung function.

Methods: Using UK Biobank data, we tested the association of 391 genes known to influence lung development with FVC and FEV₁/FVC. We split the dataset into two random subsets of 207,616 and 138,411 individuals, using the larger subset to select the most promising signals and the smaller subset for replication.

Measurements and Main Results: We identified 55 genes, of which 36 (16 for FVC, 19 for FEV₁/FVC, and one for both) had not been identified in the largest, most recent genome-wide study of lung function. Most of these 36 signals were intronic variants; expression data from blood and lung tissue showed that the majority affect the expression of the genes they lie within. Further testing of 34 of these 36 signals in the CHARGE and SpiroMeta consortia showed that 16 replicated after Bonferroni correction and another 12 replicated at nominal significance level. Of the 55 genes, 53 fell into four biological categories whose function is to regulate organ size and cell integrity (growth factors; transcriptional regulators; cell-to-cell adhesion; extracellular matrix), suggesting that these specific processes are important for adult lung health.

Conclusions: Our study demonstrates the importance of lung development genes in regulating adult lung function and influencing both restrictive and obstructive patterns. Further investigation of these developmental pathways could lead to druggable targets.

DNA methylation is associated with lung function in never smokers

BACKGROUND

Active smoking is the main risk factor for COPD. Here, epigenetic mechanisms may play a role, since cigarette smoking is associated with differential DNA methylation in whole blood. So far, it is unclear whether epigenetics also play a role in subjects with COPD who never smoked. Therefore, we aimed to identify differential DNA methylation associated with lung function in never smokers.

METHODS

We determined epigenome-wide DNA methylation levels of 396,243 CpG-sites (Illumina 450 K) in blood of never smokers in four independent cohorts, LifeLines COPD&C (N = 903), LifeLines DEEP (N = 166), Rotterdam Study (RS)-III (N = 150) and RS-BIOS (N = 206). We meta-analyzed the cohort-specific methylation results to identify differentially methylated CpG-sites with FEV₁/FVC. Expression Quantitative Trait Methylation (eQTM) analysis was performed in the Biobank-based Integrative Omics Studies (BIOS).

RESULTS

A total of 36 CpG-sites were associated with FEV₁/FVC in never smokers at p-value< 0.0001, but the meta-analysis did not reveal any epigenome-wide significant CpG-sites. Of interest, 35 of these 36 CpG-sites have not been associated with lung function before in studies including subjects irrespective of smoking history. Among the top hits were cg10012512, cg02885771, annotated to the gene LTV1 Ribosome Biogenesis factor (LTV1), and cg25105536, annotated to Kelch Like Family Member 32 (KLHL32). Moreover, a total of 11 eQTMS were identified.

CONCLUSIONS

With the identification of 35 CpG-sites that are unique for never smokers, our study shows that DNA methylation is also associated with FEV₁/FVC in subjects that never smoked and therefore not merely related to smoking.

Relationship between advanced glycation end-product accumulation in the skin and pulmonary function

. [Purpose] This study aimed to evaluate the relationship between advanced glycation end-product accumulation and pulmonary function in a general population with normal spirometry results. [Subjects and Methods] A total of 201 subjects (mean age, 56 ± 11 years; males, 58%) enrolled in this study. Subjects were classified into two groups (younger group [<65 years old] and elderly group [≥65 years old]). Skin autofluorescence was assessed as an estimate of advanced glycation end-product. Forced vital capacity and forced expiratory volume in one second were measured using a spirometer, and the forced expiratory volume in one second/forced vital capacity ratio (FEV1/FVC) was calculated. [Results] Skin autofluorescence was not an independent factor associated with FEV1/FVC in the younger group, but both skin autofluorescence and pack-years of smoking were significant independent factors associated with FEV1/FVC in the elderly group. [Conclusion] Advanced glycation end-product accumulation, assessed by skin autofluorescence, is an independent factor negatively associated with FEV1/FVC in elderly people with normal spirometry results.

Age at menarche and lung function: a Mendelian randomization study

A trend towards earlier menarche in women has been associated with childhood factors (e.g. obesity) and hypothesised environmental exposures (e.g. endocrine disruptors present in household products). Observational evidence has shown detrimental effects of early menarche on various health outcomes including adult lung function, but these might represent spurious associations due to confounding. To address this we used Mendelian randomization where genetic variants are used as proxies for age at menarche, since genetic associations are not affected by classical confounding. We estimated the effects of age at menarche on forced vital capacity (FVC), a proxy for restrictive lung impairment, and ratio of forced expiratory volume in one second to FVC (FEV1/FVC), a measure of airway obstruction, in both adulthood and adolescence. We derived SNP-age at menarche association estimates for 122 variants from a published genome-wide meta-analysis (N = 182,416), with SNP-lung function estimates obtained by meta-analysing three studies of adult women (N = 46,944) and two of adolescent girls (N = 3025). We investigated the impact of departures from the assumption of no pleiotropy through sensitivity analyses. In adult women, in line with previous evidence, we found an effect on restrictive lung impairment with a 24.8 mL increase in FVC per year increase in age at menarche (95% CI 1.8-47.9; p = 0.035); evidence was stronger after excluding potential pleiotropic variants (43.6 mL; 17.2-69.9; p = 0.001). In adolescent girls we found an opposite effect (-56.5 mL; -108.3 to -4.7; p = 0.033), suggesting that the detrimental effect in adulthood may be preceded by a short-term post-pubertal benefit. Our secondary analyses showing results in the same direction in men and boys, in whom age at menarche SNPs have also shown association with sexual development, suggest a role for pubertal timing in general rather than menarche specifically. We found no effect on airway obstruction (FEV1/FVC).

Evidence for large-scale gene-by-smoking interaction effects on pulmonary function

Background

Smoking is the strongest environmental risk factor for reduced pulmonary function. The genetic component of various pulmonary traits has also been demonstrated, and at least 26 loci have been reproducibly associated with either FEV 1 (forced expiratory volume in 1 second) or FEV 1 /FVC (FEV 1 /forced vital capacity). Although the main effects of smoking and genetic loci are well established, the question of potential gene-by-smoking interaction effect remains unanswered. The aim of the present study was to assess, using a genetic risk score approach, whether the effect of these 26 loci on pulmonary function is influenced by smoking.

Methods

We evaluated the interaction between smoking exposure, considered as either ever vs never or pack-years, and a 26-single nucleotide polymorphisms (SNPs) genetic risk score in relation to FEV 1 or FEV 1 /FVC in 50 047 participants of European ancestry from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) and SpiroMeta consortia.

Results

We identified an interaction ( βint  = -0.036, 95% confidence interval, -0.040 to -0.032, P  = 0.00057) between an unweighted 26 SNP genetic risk score and smoking status (ever/never) on the FEV 1 /FVC ratio. In interpreting this interaction, we showed that the genetic risk of falling below the FEV /FVC threshold used to diagnose chronic obstructive pulmonary disease is higher among ever smokers than among never smokers. A replication analysis in two independent datasets, although not statistically significant, showed a similar trend in the interaction effect.

Conclusions

This study highlights the benefit of using genetic risk scores for identifying interactions missed when studying individual SNPs and shows, for the first time, that persons with the highest genetic risk for low FEV 1 /FVC may be more susceptible to the deleterious effects of smoking.

High-Resolution Time-Frequency Spectrum-Based Lung Function Test from a Smartphone Microphone

In this paper, a smartphone-based lung function test, developed to estimate lung function parameters using a high-resolution time-frequency spectrum from a smartphone built-in microphone is presented. A method of estimation of the forced expiratory volume in 1 s divided by forced vital capacity (FEV₁/FVC) based on the variable frequency complex demodulation method (VFCDM) is first proposed. We evaluated our proposed method on 26 subjects, including 13 healthy subjects and 13 chronic obstructive pulmonary disease (COPD) patients, by comparing with the parameters clinically obtained from pulmonary function tests (PFTs). For the healthy subjects, we found that an absolute error (AE) and a root mean squared error (RMSE) of the FEV₁/FVC ratio were 4.49% ± 3.38% and 5.54%, respectively. For the COPD patients, we found that AE and RMSE from COPD patients were 10.30% ± 10.59% and 14.48%, respectively. For both groups, we compared the results using the continuous wavelet transform (CWT) and short-time Fourier transform (STFT), and found that VFCDM was superior to CWT and STFT. Further, to estimate other parameters, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), and peak expiratory flow (PEF), regression analysis was conducted to establish a linear transformation. However, the parameters FVC, FEV1, and PEF had correlation factor r values of 0.323, 0.275, and -0.257, respectively, while FEV₁/FVC had an r value of 0.814. The results obtained suggest that only the FEV1/FVC ratio can be accurately estimated from a smartphone built-in microphone. The other parameters, including FVC, FEV1, and PEF, were subjective and dependent on the subject's familiarization with the test and performance of forced exhalation toward the microphone.

Mucosal-Associated Invariant T Cell Deficiency in Chronic Obstructive Pulmonary Disease

Mucosal-associated invariant T (MAIT) cells have been reported to play an important role in mucosal immunity. However, little is known about the roles of MAIT cells in chronic obstructive pulmonary disease (COPD). The aims of this study were to examine the levels of circulating MAIT cells and their subsets in COPD patients and to investigate the potential relationship between clinical parameters and MAIT cell levels. Forty-five COPD patients and 57 healthy control subjects were enrolled in the study. Circulating MAIT cells and their subset levels in the peripheral blood were measured by flow cytometry. Disease grades were classified according to the GOLD criteria for the assessment of severity of COPD. Circulating MAIT cell levels were found to be significantly reduced in COPD patients. In particular, this MAIT cell deficiency was more prominent in CD8+ and double-negative T cell subsets. Interestingly, elevated serum C-reactive protein level and reduced FEV1/FVC ratio were associated with MAIT cell deficiency in COPD patients. Furthermore, the circulating MAIT levels were found to be significantly lower in patients with moderate to severe COPD than in patients with mild COPD. Our data shows that MAIT cells are numerically deficient in the peripheral blood of patients with COPD. In addition, this MAIT cell deficiency was found to reflect inflammatory activity and disease severity. These findings provide important information for monitoring the changes in MAIT cell levels and for predicting the prognosis during the disease course.

Defining obstructive ventilatory defect in 2015

INTRODUCTION

There is no clear consensus as to what constitutes an obstructive ventilatory defect (OVD): Is it FEV1/FVC

AIM

To determine, according to the two definitions, the percentage of subjects having an OVD among them explored in a lung function exploration laboratory.

POPULATION AND METHODS

This is a retrospective study including 4,730 subjects aged 17-85 years. Subjects were divided according to the presence [physio (+) or operat (+)] or absence [physio (-) or operat (-)] of an OVD, and into younger (<45 years, n=2,076), older (≥45 years, n=2,654), smokers (n=1,208), and non-smokers (n=3,522) groups.

RESULTS

For the total sample, the younger and older groups [mean±SD of age (years), respectively, 46.7±14.1; 33.9±7.4, and 56.8±9.1], the 'physiological definition' detected, respectively, 13.46, 43.22, and 5.09% more OVD than the 'operational one' (p<0.05). In addition, the operational definition, compared with the physiological one, overdiagnosed OVD in 2.33 and 0.44% of smokers and non-smokers, respectively, and underdiagnosed it in 4.46% and 29.72% of smokers and non-smokers, respectively (p<0.05). Compared with the group 'physio (-), operat (+)', the 'physio (+), operat (-)' one was younger (74.2±4.7 years vs. 40.9±10.3 years) and had significantly higher FEV1 (62±13% vs. 78±17%) and FVC (71±15% vs. 93±19%).

CONCLUSION

The frequency of OVD much depends on the criteria used for its definition.

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Key Words

• FEV1/FVC
• fixed threshold
• guideline
• lower limit of normal
• obstructive ventilatory defect
• spirometry

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MESH Headings

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Female
• Forced Expiratory Volume
• Humans
• Male
• Middle Aged
• Pulmonary Disease, Chronic Obstructive/diagnosis
• Pulmonary Disease, Chronic Obstructive/epidemiology
• Pulmonary Disease, Chronic Obstructive/physiopathology
• Respiratory Function Tests
• Retrospective Studies
• Smoking/adverse effects
• Smoking/physiopathology
• Spirometry/methods
• Tunisia/epidemiology
• Vital Capacity

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Affiliation(s)

Zied Affes Department of Physiology and Functional Exploration, Farhat HACHED University Hospital of Sousse, Sousse, Tunisia
Salaheddine Rekik Department of Physiology and Functional Exploration, Farhat HACHED University Hospital of Sousse, Sousse, Tunisia
Helmi Ben Saad Department of Physiology and Functional Exploration, Farhat HACHED University Hospital of Sousse, Sousse, Tunisia Laboratory of Physiology, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia Research Laboratory N° LR14ES05: Interactions of the Cardiopulmonary System, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia;

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Prognostic value of forced expiratory volume in 1 second/forced vital capacity in idiopathic pulmonary fibrosis

Emphysema on high-resolution computed tomography of the chest is the recent focus in the general practice in idiopathic pulmonary fibrosis (IPF). However, adequate attention has not been paid to obstructive disorder. Therefore, we retrospectively evaluated the association between the degree of airway obstruction and longevity in IPF subjects, with a hypothesis that lower forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) has an impact on prognosis. One hundred and fourteen consecutive IPF subjects who had been diagnosed with IPF and had undergone evaluation including pulmonary function test from January 2008 to May 2013 were included in the study. The relationship between baseline data and survival was examined. FEV1/FVC was widely distributed, ranging from 48.6% to 100%. On both univariate and multivariate Cox's regression analyses, lower FEV1/FVC was significantly associated with better survival (hazard ratio of 1.07 and 1.04 and 95% confidential interval of 1.03-1.10 and 1.01-1.08, respectively). Even on analysis with backward selection, FEV1/FVC remained a significant prognostic factor. FEV1/FVC is widely distributed and negatively predicts survival in IPF. A FEV1/FVC should be assessed in "real-world" general practice. Also, the effect of smoking on the clinical course of IPF should be investigated further.

Does the FEF25-75 or the FEF75 have any value in assessing lung disease in children with cystic fibrosis or asthma?

While the FEV1 had been recognized as an excellent indicator of disability, it is not very sensitive to early and mild disease. In cystic fibrosis (CF) small airway disease is believed to be one of the early hallmarks and indices such as the FEF25-75 and FEF75 have been proposed as sensitive markers of early disease. The site of early disease in asthma is not as well worked out. Recently a study of more than 20,000 spirometries found that neither of these indices added anything to the FEV1 /FVC but that study was not disease specific and contained both adults and children and the adults were the most numerous. To see if this would be true in children, 1,175 spirograms from children 6 to 18 years of age with CF or asthma whose FEV1 and FVC were above the lower limit of normal were taken from sequential studies. The data expressed in z scores was plotted with either the FEF25-75 or FEF75 plotted against FEV1 /FVC. In both diseases, but particularly in asthma, the FEV1 /FVC was more likely to be abnormal than either of the other two indices for suggesting that for children, early, or mild disease will be more apparent using the FEV1 /FVC than any other index.

Change in prevalence of restrictive lung impairment in the U.S. population and associated risk factors: the National Health and Nutrition Examination Survey (NHANES) 1988-1994 and 2007-2010

Background

Data for the U.S adult population from the National Health and Nutrition Examination Survey (NHANES) were used to evaluate risk factors for a restrictive pattern on spirometry and estimate the change in its prevalence from the 1988–1994 to 2007–2010 sampling periods. Several previous epidemiologic studies used the Global Initiative for Chronic Obstructive Lung Disease fixed forced expiratory volume in 1 second (FEV₁)/forced vital capacity (FVC) > 0.70 criteria for classifying restrictive pattern rather than the age-defined American Thoracic Society (ATS)/European Respiratory Society (ERS) lower limit of normal (LLN) criteria, which may lead to misclassification.

Methods

Spirometry measurements from NHANES data for the 1988–1994 and 2007–2010 periods were analyzed to estimate the age-standardized prevalence of a restrictive pattern on spirometry and the change in prevalence over time for adults aged 20–79. A restrictive pattern was defined based on ATS/ERS LLN criteria as FEV₁/FVC > LLN and FVC < LLN, and a moderate to more severe restrictive pattern was further evaluated using FEV₁ < 70% predicted. The associations between demographic and other individual risk factors for restrictive lung impairment were examined using multivariable logistic regression models for the two consecutive time periods.

Results

The overall age-standardized prevalence of restrictive pattern decreased significantly from 7.2% (1988–1994) to 5.4% (2007–2010) (p = 0.0013). The prevalence of moderate to more severe restrictive pattern also decreased significantly from 2.0% to 1.4% (p = 0.023). Factors positively associated with restrictive pattern on spirometry included age, female sex, white race, lower education, former and current smoking, and comorbidities including doctor-diagnosed cardiovascular disease, doctor-diagnosed diabetes, and abdominal obesity.

Conclusions

The overall prevalence of restrictive pattern and moderate to more severe restrictive pattern decreased between the 1988–1994 and 2007–2010 survey periods despite a population increase in the proportion of comorbidities associated with restrictive pattern (i.e. diabetes and abdominal obesity). This suggests a decline in individual risk factors for restrictive pattern and a need for future research.

Forced Expiratory Volume in 6 s (FEV6) and FEV1/FEV6 Values as a Viable Alternative for Forced Vital Capacity (FVC) and FEV1/FVC Values During Pregnancy in South East Nigeria: A Preliminary Study

BACKGROUND

Forced expiratory volume in 6 s (FEV6) and FEV1/FEV6 ratio have traditionally been used as a surrogate for forced vital capacity (FVC) and FEV1/FVC in the assessment of spirometric lung function in nonpregnant subjects. However, the existence of this relationship during pregnancy is yet to be ascertained.

AIM

The aim of this study was to determine if FEV6 and FEV1/FEV6 can effectively be used instead of FVC and FEV1/FVC in the interpretation of lung function test during pregnancy.

SUBJECTS AND METHODS

This study was a descriptive cross-sectional study carried out among 200 pregnant women who were recruited by using systematic random sampling during the period between April and October 2011. One hundred matched nonpregnant women served as control. A standard spirometer was used to determine the FVC, FEV6, FEV1/FVC, and FEV1/FEV6. Data analysis was done using SPSS version 11.0 (Chicago, IL, USA). Values were recorded as mean (standard deviation), and also median and interquartile ranges. The one-way analysis of variance, Mann-Whitey U and the Kruskal-Wallis were used to test for significance where applicable. P <0.05 were considered to be significant.

RESULTS

All the values were within normal range, but the FVC and FEV6 decreased significantly while the FEV1/FVC and FEV1/FEV6 increased as pregnancy progressed. However, for first and last trimester, FVC differed significantly from FEV6. The values of the FVC were comparable to the values of FEV6. The FEV1/FVC and FEV1/FEV6 ratio were similar and well above the 0.7 cutoff for obstructive lung diseases.

CONCLUSION

FEV6 requires a short exhalation time and can effectively be used in place of FVC in evaluation of lung function test during pregnancy. The FEV1/FEV6 may be applied as a proxy for FEV1/FVC in pregnant and nonpregnant women.

Heritability of pulmonary function estimated from pedigree and whole-genome markers

Asthma and chronic obstructive pulmonary disease (COPD) are major worldwide health problems. Pulmonary function testing is a useful diagnostic tool for these diseases, and is known to be influenced by genetic and environmental factors. Previous studies have demonstrated that a substantial proportion of the variation in pulmonary function phenotypes can be explained by familial relationships. The availability of whole-genome single nucleotide polymorphism (SNP) data enables us to further evaluate the extent to which genetic factors account for variation in pulmonary function and to compare pedigree- to SNP-based estimates of heritability. Here, we employ methods developed in the animal breeding field to estimate the heritability of forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and the ratio of these two measures (FEV1/FVC) among subjects in the Framingham Heart Study dataset. We compare heritability estimates based on pedigree-based relationships to those based on genome-wide SNPs. We find that, in a family-based study, estimates of heritability using SNP data are nearly identical to estimates based on pedigree information, and range from 0.50 for FEV1 to 0.66 for FEV1/FVC. Therefore, we conclude that genetic factors account for a sizable proportion of inter-individual differences in pulmonary function, and that estimates of heritability based on SNP data are nearly identical to estimates based on pedigree data. Finally, our findings suggest a higher heritability for FEV1/FVC compared to either FEV1 or FVC.

Long-term use of doxycycline can improve chronic asthma and possibly remodeling: the result of a pilot observation

Progressive loss of lung function and reversibility characterize chronic asthma. The conventional therapy is targeted to control the disease without targeting the loss of lung function or reversibility. In a prospective real-world observation of long-term use of add-on doxycycline as a matrix-metalloproteinase inhibitor, we documented significant improvement in lung function with possible reversal of remodeling.