Clinical interpretation of airway response to a bronchodilator. Epidemiologic considerations

A genome-wide association study of bronchodilator response in participants of European and African ancestry from six independent cohorts

Introduction

Bronchodilator response (BDR) is a measurement of acute bronchodilation in response to short-acting β2-agonists, with a heritability between 10 and 40%. Identifying genetic variants associated with BDR may lead to a better understanding of its complex pathophysiology.

Methods

We performed a genome-wide association study (GWAS) of BDR in six adult cohorts with participants of European ancestry (EA) and African ancestry (AA) including community cohorts and cohorts ascertained on the basis of obstructive pulmonary disease. Validation analysis was carried out in two paediatric asthma cohorts.

Results

A total of 10 623 EA and 3597 AA participants were included in the analyses. No single nucleotide polymorphism (SNP) was associated with BDR at the conventional genome-wide significance threshold (p<5×10-8). Performing fine mapping and using a threshold of p<5×10-6 to identify suggestive variants of interest, we identified three SNPs with possible biological relevance: rs35870000 (within FREM1), which may be involved in IgE- and IL5-induced changes in airway smooth muscle cell responsiveness; rs10426116 (within ZNF284), a zinc finger protein, which has been implicated in asthma and BDR previously; and rs4782614 (near ATP2C2), involved in calcium transmembrane transport. Validation in paediatric cohorts yielded no significant SNPs, possibly due to age-genotype interaction effects.

Conclusion

Ancestry-stratified and ancestry-combined GWAS meta-analyses of over 14 000 participants did not identify genetic variants associated with BDR at the genome-wide significance threshold, although a less stringent threshold identified three variants showing suggestive evidence of association. A common definition and protocol for measuring BDR in research may improve future efforts to identify variants associated with BDR.

Clinical value of bronchodilator response for diagnosing asthma in steroid-naïve adults

Spirometry and testing for bronchodilator response have been recommended to detect asthma, and a bronchodilator response (BDR) of ≥12% and ≥200 mL has been suggested to confirm asthma. However, the clinical value of bronchodilation tests in newly diagnosed steroid-naïve adult patients with asthma remains unknown. We evaluated the sensitivity of BDR in forced expiratory volume in 1 s (FEV₁) as a diagnostic test for asthma in a real-life cohort of participants in the Seinäjoki Adult Asthma Study. In the diagnostic phase, 369 spirometry tests with bronchodilation were performed for 219 steroid-naïve patients. The fulfilment of each test threshold was assessed. According to the algorithm of the National Institute for Health and Care Excellence, we divided the patients into obstructive (FEV₁/forced vital capacity (FVC) <0.70) and non-obstructive (FEV₁/FVC ≥0.70) groups. Of the overall cohort, 35.6% fulfilled ΔFEV₁ ≥12% and ≥200 mL for the initial FEV₁, 18.3% fulfilled ΔFEV₁ ≥15% and ≥400 mL for the initial FEV₁, and 36.1% fulfilled ΔFEV₁ ≥9% of predicted FEV₁ at least once. One-third (31%) of these steroid-naïve patients was obstructive (pre-bronchodilator FEV₁/FVC <0.7). Of the obstructive patients, 55.9%, 26.5% and 48.5%, respectively, met the same thresholds. In multivariate logistic regression analysis, different thresholds recognised different kinds of asthma patients. In steroid-naïve adult patients, the current BDR threshold (ΔFEV₁ ≥12% and ≥200 mL) has low diagnostic sensitivity (36%) for asthma. In obstructive patients, sensitivity is somewhat higher (56%) but far from optimal. If the first spirometry test with bronchodilation is not diagnostic but asthma is suspected, spirometry should be repeated, and other lung function tests should be used to confirm the diagnosis.

Bronchodilator reversibility as a diagnostic test for adult asthma: findings from the population-based Tasmanian Longitudinal Health Study

Bronchodilator reversibility (BDR) is often used as a diagnostic test for adult asthma. However, there has been limited assessment of its diagnostic utility. We aimed to determine the discriminatory accuracy of common BDR cut-offs in the context of current asthma and asthma–COPD overlap (ACO) in a middle-aged community sample.

The Tasmanian Longitudinal Health Study is a population-based cohort first studied in 1968 (n=8583). In 2012, participants completed respiratory questionnaires and spirometry (n=3609; mean age 53 years). Receiver operating characteristic (ROC) curves were fitted for current asthma and ACO using continuous BDR measurements. Diagnostic parameters were calculated for different categorical cut-offs.

Area under the ROC curve (AUC) was highest when BDR was expressed as change in forced expiratory volume in 1 s (FEV₁) as a percentage of initial FEV₁, as compared with predicted FEV₁. The corresponding AUC was 59% (95% CI 54–64%) for current asthma and 87% (95% CI 81–93%) for ACO. Of the categorical cut-offs examined, the European Respiratory Society/American Thoracic Society threshold (≥12% from baseline and ≥200 mL) was assessed as providing the best balance between positive and negative likelihood ratios (LR+ and LR−, respectively), with corresponding sensitivities and specificities of 9% and 97%, respectively, for current asthma (LR+ 3.26, LR− 0.93), and 47% and 97%, respectively, for ACO (LR+ 16.05, LR− 0.55).

With a threshold of ≥12% and ≥200 mL from baseline, a positive BDR test provided a clinically meaningful change in the post-test probability of disease, whereas a negative test did not. BDR was more useful as a diagnostic test in those with co-existent post-bronchodilator airflow obstruction (ACO).

Using the commonly adopted threshold, a positive BDR test provides a meaningful change in post-test probability of adult asthma, whereas a negative test does not. Discriminatory accuracy is much greater in those with coexistent post-BD airflow obstruction.https://bit.ly/3gPvlm8

Current Bronchodilator Responsiveness Criteria Underestimate Asthma in Older Adults

BACKGROUND

Asthma is common in older adults and is confirmed by demonstration of variable expiratory air-flow limitations, typically evaluated by spirometric assessment of bronchodilator responsiveness. However, many patients with clinically suspected asthma and documented air-flow obstruction do not exhibit a post-bronchodilator response that meets or exceeds current established guidelines. We investigated if extending the time from bronchodilator administration to assessment of bronchodilator response increases the yield of spirometry for the diagnosis of asthma in older adults.

METHODS

This was a cross-sectional study. The subjects were non-smokers, ≥ 60 y old, and with suspected asthma. Subjects were characterized as (1) those with a positive bronchodilator response on the 30-min post-bronchodilator spirometry, (2) those with a positive bronchodilator response on the 60-min post-bronchodilator spirometry, and (3) those without a positive bronchodilator response but with a positive methacholine challenge test. Factors associated with a late response to bronchodilator were evaluated by using bivariate analysis and by multivariate analysis by using a logistic regression model.

RESULTS

This study enrolled 165 subjects. Of these, 81 (49.1%) had a positive bronchodilator response on 30-min post-bronchodilator spirometry; 25 (15.2%) had a positive bronchodilator response on the 1-h post-bronchodilator spirometry; and 59 (35.8%) had no positive bronchodilator response but had a positive methacholine challenge test. On multivariable regression analysis, those with a higher baseline percentage of predicted FEV₁, higher scores on a standard asthma control test, and wheezing and/or cough after exercise were more likely to either have a late bronchodilator response or no bronchodilator response.

CONCLUSIONS

Our study showed that a late positive response to bronchodilator use was more common than previously presumed in older subjects with suspected asthma. Pulmonary function testing laboratories should consider routinely reassessing spirometry at 1 h after bronchodilator use if the earlier assessment did not reveal a significant response.

Longitudinal Relationships between Asthma-Specific Quality of Life and Asthma Control in Children; The Influence of Chronic Rhinitis

Managing pediatric asthma includes optimizing both asthma control and asthma-specific quality of life (QoL). However, it is unclear to what extent asthma-specific QoL is related to asthma control or other clinical characteristics over time. The aims of this study were to assess in children longitudinally: (1) the association between asthma control and asthma-specific QoL and (2) the relationship between clinical characteristics and asthma-specific QoL. In a 12-month prospective study, asthma-specific QoL, asthma control, dynamic lung function indices, fractional exhaled nitric oxide, the occurrence of exacerbations, and the use of rescue medication were assessed every 2 months. Associations between the clinical characteristics and asthma-specific QoL were analyzed using linear mixed models. At baseline, the QoL symptom score was worse in children with asthma and concomitant chronic rhinitis compared to asthmatic children without chronic rhinitis. An improvement of asthma control was longitudinally associated with an increase in asthma-specific QoL (p-value < 0.01). An increased use of β₂-agonists, the occurrence of wheezing episodes in the year before the study, the occurrence of an asthma exacerbation in the 2 months prior to a clinical visit, and a deterioration of lung function correlated significantly with a decrease in the Pediatric Asthma Quality of Life Questionnaire (PAQLQ) total score (p-values ≤ 0.01). Chronic rhinitis did not correlate with changes in the PAQLQ score over 1 year. The conclusion was that asthma control and asthma-specific QoL were longitudinally associated, but were not mutually interchangeable. The presence of chronic rhinitis at baseline did influence QoL symptom scores. β₂-agonist use and exacerbations before and during the study were inversely related to the asthma-specific QoL over time.

A New Bronchodilator Response Grading Strategy Identifies Distinct Patient Populations

Rationale: A positive bronchodilator response (BDR) according to American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines require both 200 ml and 12% increase in forced expiratory volume in 1 second (FEV1) or forced vital capacity (FVC) after bronchodilator inhalation. This dual criterion is insensitive in those with high or low FEV1.Objectives: To establish BDR criteria with volume or percentage FEV1 change.Methods: The largest FEV1 and FVC were identified from three pre- and three post-bronchodilator maneuvers in COPDGene (Genetic Epidemiology of COPD) participants. A total of 7,741 individuals with coefficient of variation less than 15% for both FEV1 and FVC formed bronchodilator categories of FEV1 response: negative (≤0.00% or ≤0.00 L), minimal (>0.00% to ≤9.00% or >0.00 L to ≤0.09 L), mild (>9.00% to ≤16.00% or >0.09 L to ≤0.16 L), moderate (>16.00% to ≤26.00% or >0.16 L to ≤0.26 L), and marked (>26.00% or >0.26 L). These response size categories are based on empirical limits considering average FEV1 increase of approximately 160 ml and the clinically important difference for FEV1. To compare flow and volume response characteristics, BDR-FEV1 category assignments were applied for the BDR-FVC response.Results: Twenty percent met mild and 31% met moderate or marked BDR-FEV1 criteria, whereas 12% met mild and 33% met moderate or marked BDR-FVC criteria. In contrast, only 20.6% met ATS/ERS positive criteria. Compared with the negative BDR-FEV1 category, the minimal, mild, moderate, and marked BDR-FEV1 categories were associated with greater 6-minute-walk distance and lower St. George's Respiratory Questionnaire and modified Medical Research Council dyspnea scale scores. Compared with negative BDR, moderate and marked BDR-FEV1 categories were associated with fewer exacerbations, and minimal BDR was associated with lower computed tomography airway wall thickness. Compared with the negative category, all BDR-FVC categories were associated with increasing emphysema percentage and gas trapping percentage. Moderate and marked BDR-FVC categories were associated with higher St. George's Respiratory Questionnaire scores but fewer exacerbations and lower dyspnea scores.Conclusions: BDR grading by FEV1 volume or percentage response identified subjects otherwise missed by ATS/ERS criteria. BDR grades were associated with functional exercise performance, quality of life, exacerbation frequency, dyspnea, and radiological airway measures. BDR grades in FEV1 and FVC indicate different clinical and radiological characteristics.

Immediate bronchodilator response in FEV1 as a diagnostic criterion for adult asthma

Asthma is characterised by variable and reversible expiratory airflow limitations. Thus, it is logical to use the change in forced expiratory volume in 1 s (FEV₁) in response to a bronchodilator (ΔFEV₁BDR) as a diagnostic tool; increases of ≥12% and ≥200 mL from the baseline FEV₁ are commonly used values. We aimed to evaluate the historical development of diagnostic cut-off levels for the ΔFEV₁BDR for adults and the evidence behind these recommendations.We searched for studies from the reference lists of all the main statements, reports and guidelines concerning the interpretation of spirometry and diagnostics for asthma and conducted a literature search.A limited amount of evidence regarding the ΔFEV₁BDR in healthy populations was found, and even fewer patient studies were found. In healthy persons, the upper 95th percentile for the absolute ΔFEV₁BDR ranges between 240 mL and 320 mL, the relative ΔFEV₁BDR calculated from the initial FEV₁ ranges from 5.9% to 13.3% and the ΔFEV₁BDR calculated from the predicted FEV₁ ranges from 8.7% to 11.6%. However, the absolute and percentage ΔFEV₁BDR values calculated from the initial FEV₁ are dependent on age, sex, height and the degree of airway obstruction. Thus, the use of the ΔFEV₁BDR calculated from the predicted FEV₁ might be more appropriate.Not enough data exist to assess the sensitivity of any of the cut-off levels for the ΔFEV₁BDR to differentiate asthma patients from healthy subjects. Further studies in newly diagnosed asthma patients are needed.

Two vs four puffs of albuterol: does dose change bronchodilator response?

Background

Reversible obstruction on spirometry may be used to diagnose asthma. As per 2005 American Thoracic Society (ATS) guidelines, our pulmonary center began using 360 µg (four puffs) of albuterol rather than 180 µg (two puffs) to determine reversibility on spirometry starting in 2009.

Hypothesis

We hypothesized that fewer patients would respond to two puffs of albuterol than four puffs during spirometric testing.

Methods

We retrospectively reviewed records from new asthmatics seen in Pediatric Pulmonary Clinic from March 2002 to April 2014 who performed reproducible spirometry. Patients were divided into two groups based on whether they had received two or four puffs of albuterol for bronchodilator assessment. A positive bronchodilator response was defined as an increase of ≥12% in forced expiratory volume in one second (FEV₁) or ≥25% in forced expiratory flow (FEF_25–75%). Data were expressed as percentages and mean ± standard error of the mean values. Chi-squared test and Student’s t-test were utilized.

Results

Data were collected for 240 patients; 115 patients received two puffs of albuterol and 125 patients received four puffs. There were no significant differences in baseline characteristics between the two groups. There were no differences following two puffs or four puffs in changes in FEV₁ (10.0±1.1% vs 10.5±1.1% predicted) or FEF_25–75% (30.2±2.9% vs 33.5±2.9% predicted). Moreover, there was no difference in ATS-defined bronchodilator response between the two groups.

Conclusion

Based on the mean change in FEV₁ and overall bronchodilator responsiveness, two puffs of albuterol were not inferior to four puffs in the determination of bronchodilator responsiveness in our pediatric asthmatic patients.

Turkish Thoracic Society Consensus Report: Interpretation of Spirometry

ÖZET: Günümüzde spirometre ölçümlerinin uygulama ve yorumlama nitelik güvencesi "American Thoracic Society / European Respiratory Society" standartları ile belirlenmiştir. Dünyada olduğu gibi ülkemizde de birçok laboratuvar bu standartları kullanmaktadır. Buna karşın, farklı laboratuvarlardan farklı değerlendirme sonuçları görebilmek mümkündür. Bu rapor, ülkemizdeki solunum fonksiyon testi laboratuvarlarında yapılan değerlendirmelerin standardizasyonunu sağlamak amacı ile hazırlanmıştır.

Gut microbiota components are associated with fixed airway obstruction in asthmatic patients living in the tropics

Microbiome composition has been associated to several inflammatory diseases, including asthma. There are few studies exploring the relationships of gut microbiota with airway obstruction pheonotypes in adult asthma, especially those living in the tropics. We sought to evaluate the relationships of gut microbiota with the airway obstruction and other variables of interest in asthmatic patients living in the tropics according to three phenotypes: No Airway Obstruction (NAO), Reversible Airway Obstruction (RAO) or Fixed Airway Obstruction (FAO). We found that Streptococcaceae:Streptococcus and Enterobacteriaceae:Escherichia-Shigella consistently discriminated asthmatic individuals suffering FAO from NAO or RAO, plus Veillonellaceae:Megasphaera when comparing FAO and RAO (p < 0.05; FDR < 0.05). In the FAO, the network showing the genus relations was less complex and interconnected. Several Rumminococcaceae, Lachnospiraceae and Clostridiales were enriched in patients with low specific IgE levels to mites and Ascaris. All patients shared a common exposure framework; control medication usage and smoking habit were uncommon and equally distributed between them. In conclusion, in this tropical asthmatic population, components of human gut microbiota are associated with the presence of a FAO phenotype and lower specific IgE response to mites and Ascaris.

Pulmonary Function Tests for the Generalist: A Brief Review

One of the frequent reasons patients see their primary care physicians is for the symptom of dyspnea. Among the objective tests to quantify this symptom is the pulmonary function test, which includes several different studies: spirometry with flow-volume loop, lung volumes, and diffusing capacity of lung for carbon monoxide. The results may indicate both respiratory and nonrespiratory disorders, including helping in the diagnosis of cardiac or neuromuscular diseases. This review, intended for the generalist, describes common findings of pulmonary function tests and provides a road map for interpretation.

Impulse oscillometry and spirometry exhibit different features of lung function in bronchodilation

OBJECTIVE

Bronchodilator responses (BDRs) from impulse oscillometry (IOS) are not interchangeable with those from spirometry. We aimed to identify the characteristics of children with small airway hyperresponsiveness and to determine whether BDR from IOS provides an important supplement to BDR from spirometry.

METHODS

The records of 592 children with asthma or suspected asthma who underwent spirometric and oscillometric BDRs were retrospectively reviewed. Oscillometric BDR was defined as positive when relative or absolute changes of Rrs₅ or Xrs₅ were beyond two standard deviations and spirometric BDR as positive when absolute change of forced expiratory volume in one second (FEV₁) was ≥12%. Subjects were classified as positive for spirometric BDR only, positive for oscillometric BDR only, positive for both BDRs, or negative for both BDRs.

RESULTS

The results indicated that 101 (17.6%) subjects were positive for spirometric BDR only, 49 (8.5%) positive for oscillometric BDR only, 48 (8.3%) positive for both BDRs, and 377 (65.6%) negative for both BDRs. The agreement between spirometric and oscillometric BDRs was poor. Baseline FEV₁, Rrs₅, and Xrs₅ values strongly influenced the BDRs. Subjects positive for oscillometric BDR only were found to be younger than those positive for spirometric BDR only (P < 0.001). Subjects positive for both BDRs were more likely to have asthma, atopic dermatitis, wheezing apart from cold, or decreased baseline lung function relative to those positive in either test (P < 0.001).

CONCLUSIONS

There was a low concordance between spirometric and oscillometric BDRs. Use of IOS to detect small airway hyperresponsiveness may add more information about a clinical profile of subjects with asthma.

Post-bronchodilator Reversibility of FEV1 and Eosinophilic Airway Inflammation in COPD

INTRODUCTION

The relationship between bronchodilator responsiveness and eosinophilic airway inflammation has not been well documented in COPD. It has been investigated in this retrospective study. This issue has grown in importance due to increasing interest in the asthma-COPD overlap syndrome.

METHODS

264 stable COPD patients with no past history of asthma were retrospectively analyzed. Correlation analyses between FEV₁ reversibility and sputum eosinophil levels were conducted. Sputum eosinophil levels were dichotomized using FEV₁ reversibility cut-off points (>0.4L and >15% vs. >0.2L and >12%) and compared. The effectiveness of FEV₁ reversibility to predict sputum eosinophilia (>3%) was analyzed with a logistic regression and a ROC analysis.

RESULTS

82 (31.1%) patients with higher FEV₁ reversibility values (0.14 vs. 0.11L, P=.01) presented sputum eosinophilia. FEV₁ reversibility was weakly correlated with the sputum eosinophil level (r=0.162, P=.008). Patients with FEV₁>0.4L and >15% increment had higher sputum eosinophil levels (6.11 vs. 1.02%, P=.049) whereas the level did not differ when dichotomized by FEV₁ increment >0.2L and >12%. Very positive FEV₁ reversibility (>0.4L and >15%) predicted sputum eosinophilia after adjustment forage, baseline FEV₁ and FVC (OR: 4.262, P=.029). In the ROC analysis, the AUC was 0.58 (P=.034), and FEV₁ increment>0.4L and >15% had a positive predictive value of 63.6% and an overall accuracy of 70.1%.

CONCLUSIONS

FEV₁ reversibility was weakly correlated with sputum eosinophil levels in COPD. Positive FEV₁ reversibility (>0.4L and >15%) is moderately successful in predicting sputum eosinophilia (>3%).

Measures of bronchodilator response of FEV1, FVC and SVC in a Swedish general population sample aged 50-64 years, the SCAPIS Pilot Study

BACKGROUND

Data are lacking from general population studies on how to define changes in lung function after bronchodilation. This study aimed to analyze different measures of bronchodilator response of forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC) and slow vital capacity (SVC).

MATERIALS AND METHODS

Data were derived from the Swedish Cardiopulmonary Bioimage Study (SCAPIS) Pilot study. This analysis comprised 1,050 participants aged 50-64 years from the general population. Participants were investigated using a questionnaire, and FEV1, FVC and SVC were recorded before and 15 minutes after inhalation of 400 µg of salbutamol. A bronchodilator response was defined as the relative change from baseline value expressed as the difference in units of percent predicted normal. Predictors of bronchodilator responses were assessed using multiple linear regression models. Airway obstruction was defined as FEV1/FVC ratio below lower limit of normal (LLN) before bronchodilation, and COPD was defined as an FEV1/FVC ratio below LLN after bronchodilation. Physician-diagnosed asthma was defined as an affirmative answer to "Have you ever had asthma diagnosed by a physician?". Asymptomatic never-smokers were defined as those not reporting physician-diagnosed asthma, physician-diagnosed COPD or emphysema, current wheeze or chronic bronchitis and being a lifelong never-smoker.

RESULTS

Among all subjects, the greatest bronchodilator responses (FEV1, FVC and SVC) were found in subjects with asthma or COPD. The upper 95th percentile of bronchodilator responses in asymptomatic never-smokers was 8.7% for FEV1, 4.2% for FVC and 5.0% for SVC. The bronchodilator responses were similar between men and women. In a multiple linear regression model comprising all asymptomatic never-smokers, the bronchodilator response of FEV1 was significantly associated with airway obstruction and height.

CONCLUSION

When the bronchodilator response in asymptomatic never-smokers is reported as the difference in units of predicted normal, significant reversibility of FEV1, FVC and SVC to bronchodilators is ~9%, 4% and 5%, respectively.

Is the bronchodilator test an useful tool to measure asthma control?

INTRODUCTION

Asthma control includes the control of symptoms and future risk. We sought to evaluate the usefulness of the degree of spirometric reversibility of the forced expiratory volume in one second (FEV₁) as the target parameter of control.

METHODOLOGY

Patients with bronchial asthma were followed up for one year. The clinical, functional, inflammatory and control parameters of the asthma were collected. The area under the curve (AUC) was estimated to establish the cutoff point of the post-bronchodilator FEV₁ reversibility in relation to non-control asthma. In the univariate analysis, the differences between groups were studied based on the degree of estimated reversibility. Factors with a significance <0.1 were included in the multivariate analysis by binary logistic regression.

RESULTS

A total of 407 patients with a mean age of 38.1 ± 16.7 years were included. When the patients were grouped into controlled and non-controlled groups, compared with post-bronchodilator FEV₁ reversibility, the cutoff point obtained for the non-controlled group was ≥10% (sensitivity: 65.8%, specificity: 48.4%, positive predictive value: 69.5%, and AUC: 0.619 [0.533-0.700], p < 0.01). In the year-long follow-up of this group (post-bronchodilator FEV₁ ≥10), an increased use of relief medication was observed, along with a significantly progressive drop in post-bronchodilator FEV₁ and post-bronchodilator FEV₁/FVC (forced expiratory volume in one second/forced vital capacity).

CONCLUSIONS

Spirometric reversibility can be useful in assessing control in asthmatic patients and can predict future risk parameters. The cutoff point related to the non-control of asthma found in our work was ≥10%.

Can exhaled volatile organic compounds predict asthma exacerbations in children?

BACKGROUND

Asthma control does not yet meet the goals of asthma management guidelines. Non-invasive monitoring of airway inflammation may help to improve the level of asthma control in children.

OBJECTIVES

(1) To identify a set of exhaled volatile organic compounds (VOCs) that is most predictive for an asthma exacerbation in children. (2) To elucidate the chemical identity of predictive biomarkers.

METHODS

In a one-year prospective observational study, 96 asthmatic children participated . During clinical visits at 2 month intervals, asthma control, fractional exhaled nitric oxide, lung function (FEV₁, FEV₁/VC) and VOCs in exhaled breath were determined by means of gas chromatography time-of-flight mass spectrometry. Random Forrest classification modeling was used to select predictive VOCs, followed by plotting of receiver operating characteristic-curves (ROC-curves).

RESULTS

An inverse relationship was found between the predictive power of a set of VOCs and the time between sampling of exhaled breath and the onset of exacerbation. The sensitivity and specificity of the model predicting exacerbations 14 days after sampling were 88% and 75%, respectively. The area under the ROC-curve was 90%. The sensitivity for prediction of asthma exacerbations within 21 days after sampling was 63%. In total, 7 VOCs were selected for the classification model: 3 aldehydes, 1 hydrocarbon, 1 ketone, 1 aromatic compound, and 1 unidentified VOC.

CONCLUSION

VOCs in exhaled breath showed potential for predicting asthma exacerbations in children within 14 days after sampling. Before using this in clinical practice, the validity of predicting asthma exacerbations should be studied in a larger cohort.

A literature review of the evidence that a 12% improvement in FEV1 is an appropriate cut-off for children

INTRODUCTION

A well-performed spirometry, using a change in forced expiratory volume in one second (FEV(1)) after albuterol, is commonly used to support the likelihood of an asthma diagnosis. The current standard, accepted by the 2007 National Heart Lung and Blood Institute Asthma Expert Panel Report-3 (EPR-3) guidelines, is a 12% improvement in the FEV(1) after a bronchodilator.

OBJECTIVE

We sought to determine whether existing studies support or refute using a 12% improvement as a significant change in FEV(1) in children and adolescents.

DATA SOURCES

We reviewed the literature of children and adolescents using Medline searches to discover pertinent population studies and comparative studies that included FEV(1) measurements.

RESULT

The majority of the discovered studies suggest a less stringent improvement in FEV(1) in children might be applicable.

CONCLUSION

Supported by the published literature, we suggest an alternative interpretive strategy of expressing the results of a spirometry measurement when a diagnosis of asthma in a child is being considered using a bronchodilator response.

Improved criterion for assessing lung function reversibility

BACKGROUND

Consensus on how best to express bronchodilator reversibility (BDR) is lacking. We tested different BDR criteria against the null hypotheses that BDR should show no sex or size bias. To determine the best criterion for defining BDR, we hypothesized that clinically important BDR should be associated with better survival in respiratory patients compared with that of patients without BDR.

METHODS

We used the first BDR test of 4,231 patients who had known subsequent survival status (50.8% male sex; mean age, 60.9 years; mean survival, 5.2 years [range, 0.1-16.5 years]). BDR for FEV1 was expressed as absolute change, % baseline change, and change as % predicted FEV1.

RESULTS

Having BDR defined from absolute change was biased toward men (male to female ratio, 2.70) and toward those with larger baseline FEV1. BDR defined by % change from baseline was biased toward those with lower baseline values. BDR defined by % predicted had no sex or size bias. Multivariate Cox regression found those with FEV1 BDR > 8% predicted (33% of the subjects) had an optimal survival advantage (hazard ratio, 0.56; 95% CI, 0.45-0.69) compared with those with FEV1 BDR ≤ 8% predicted. The survival of those with FEV1 BDR > 8% predicted was not significantly different from that of those with FEV1 BDR > 14% predicted but was significantly better than that of those with FEV1 BDR < 0.

CONCLUSIONS

We have shown that expressing FEV1 BDR as % predicted avoids sex and size bias. FEV1 BDR > 8% predicted showed optimal survival advantage and may be the most appropriate criterion to define clinically important reversibility.

Longitudinal assessment of airway responsiveness from 1 month to 18 years in the PIAF birth cohort

The Perth Infant Asthma Follow-up (PIAF) study involves a birth cohort of unselected subjects who have undergone longitudinal assessments of airway responsiveness at 1, 6 and 12 months and 6, 11 and 18 years of age. The aim of this study was to determine the relationship between increased airway responsiveness throughout childhood and asthma in early adult life.Airway responsiveness to histamine, assessed as a dose-response slope (DRS), and a respiratory questionnaire were completed at 1, 6 and 12 months and 6, 11 and 18 years of age.253 children were initially recruited and studied. Airway responsiveness was assessed in 203, 174, 147, 103, 176 and 137 children at the above-mentioned time points, respectively (39 participants being assessed on all test occasions). Asthma at 18 years was associated with increased airway responsiveness at 6, 12 and 18 years, but not during infancy (slope 0.24, 95% CI 0.06-0.42; p=0.01; slope 0.25, 95% CI 0.08-0.49; p=0.006; and slope 0.56, 95% CI 0.29-0.83; p<0.001, respectively).Increased airway responsiveness and its association with asthma at age 18 years is established between infancy and 6 years. We propose that airway responsiveness in early life reflects the initial airway geometry and airway responsiveness later in childhood increasingly reflects immunological responses to environmental influences.

Spirometer Replacement and Serial Lung Function Measurements in Population Studies: Results From the SAPALDIA Study

The Swiss Cohort Study on Air Pollution and Lung and Heart Disease in Adults (SAPALDIA), a population cohort study, used heated-wire spirometers in 1991 and 2002 and then ultrasonic spirometers in 2010 revealing measurement bias in healthy never smokers. To provide a practical method to control for measurement bias given the replacement of spirometer in long-term population studies, we built spirometer-specific reference equations from healthy never smokers participating in 1991, 2002, and 2010 to derive individualized corrections terms. We compared yearly lung function decline without corrections terms with fixed terms that were obtained from a quasi-experimental study and individualized terms. Compared with baseline reference equations, spirometer-specific reference equations predicted lower lung function. The mean measurement bias increased with age and height. The decline in forced expiratory volume in 1 second during the reference period of 1991-2002 was 31.5 (standard deviation (SD), 28.7) mL/year while, after spirometer replacement, uncorrected, corrected by fixed term, and individualized term, the declines were 47.0 (SD, 30.1), 40.4 (SD, 30.1), and 30.4 (SD, 29.9) mL/year, respectively. In healthy never smokers, ultrasonic spirometers record lower lung function values than heated-wire spirometers. This measurement bias is sizeable enough to be relevant for researchers and clinicians. Future reference equations should account for not only anthropometric variables but also spirometer type. We provide a novel method to address spirometer replacement in cohort studies.

Modest genetic influence on bronchodilator response: a study in healthy twins

Aim

To determine the reasons for large standard deviation of bronchodilator response (BDR) and establish whether there is a potential heritable component in healthy subjects.

Methods

67 monozygotic and 42 dizygotic adult twin pairs were assessed for bronchodilator response (%change in FEV₁ after inhaling 400 µg salbutamol). Univariate quantitative genetic modeling was performed.

Results

Multiple regression modeling showed a significant association between BDR and sex and baseline FEV1 (P < 0.05), while no association was found with smoking habits, body mass index, or age. Within pair correlation in monozygotic twins was modest (0.332), but higher than in dizygotic twins (0.258). Age-, sex-, and baseline FEV1-adjusted genetic effect accounted for 14.9% (95% confidence interval, CI 0%-53.1%) of the variance of BDR, shared environmental effect for 18.4% (95% CI 0%-46.8%), and unshared environmental effect for 66.8% (95% CI 46.8%-88.7%).

Conclusion

Our twin study showed that individual differences in BDR can be mostly explained by unshared environmental effects. In addition, it is the first study to show low, insignificant hereditary influences, independently from sex, age, and baseline FEV1.

Prediction of asthma exacerbations in children by innovative exhaled inflammatory markers: results of a longitudinal study

BACKGROUND

In asthma management guidelines the primary goal of treatment is asthma control. To date, asthma control, guided by symptoms and lung function, is not optimal in many children and adults. Direct monitoring of airway inflammation in exhaled breath may improve asthma control and reduce the number of exacerbations.

AIM

1) To study the use of fractional exhaled nitric oxide (FeNO) and inflammatory markers in exhaled breath condensate (EBC), in the prediction of asthma exacerbations in a pediatric population. 2) To study the predictive power of these exhaled inflammatory markers combined with clinical parameters.

METHODS

96 asthmatic children were included in this one-year prospective observational study, with clinical visits every 2 months. Between visits, daily symptom scores and lung function were recorded using a home monitor. During clinical visits, asthma control and FeNO were assessed. Furthermore, lung function measurements were performed and EBC was collected. Statistical analysis was performed using a test dataset and validation dataset for 1) conditionally specified models, receiver operating characteristic-curves (ROC-curves); 2) k-nearest neighbors algorithm.

RESULTS

Three conditionally specified predictive models were constructed. Model 1 included inflammatory markers in EBC alone, model 2 included FeNO plus clinical characteristics and the ACQ score, and model 3 included all the predictors used in model 1 and 2. The area under the ROC-curves was estimated as 47%, 54% and 59% for models 1, 2 and 3 respectively. The k-nearest neighbors predictive algorithm, using the information of all the variables in model 3, produced correct predictions for 52% of the exacerbations in the validation dataset.

CONCLUSION

The predictive power of FeNO and inflammatory markers in EBC for prediction of an asthma exacerbation was low, even when combined with clinical characteristics and symptoms. Qualitative improvement of the chemical analysis of EBC may lead to a better non-invasive prediction of asthma exacerbations.

Relationship between expression of matrix metalloproteinase-9 and adenylyl cyclase-associated protein 1 in chronic obstructive pulmonary disease

OBJECTIVE

To investigate the relationship between expression of matrix metalloproteinase (MMP)-9 and expression of adenylyl cyclase-associated protein (CAP)-1 in chronic obstructive pulmonary disease (COPD).

METHODS

Patients with possible respiratory disease were recruited into the study and divided into a COPD group and a non-COPD group on diagnosis. Pulmonary function tests were performed and serum concentrations of MMP-9 were measured using an enzyme-linked immunosorbent assay. MMP-9 and CAP1 expression were analysed in lung tissue and bronchoalveolar lavage fluid in all available samples using immunohistochemistry and Western blot, respectively. In addition, expression of MMP-9 and CAP1 in vitro was investigated using immunofluorescence. Expression of CAP1 in response to MMP-9 was measured in the human alveolar epithelial cell line HP-AEpiC, using Western blot.

RESULTS

A total of 90 patients were included in the study: 52 were in the COPD group and 38 in the non-COPD group. Serum MMP-9 concentrations were significantly higher in the COPD than in the non-COPD group. MMP-9 serum concentrations were negatively correlated with forced expiratory volume in 1 s (FEV1), FEV1 as a percentage of the normal predicted value and the ratio of FEV1 to forced vital capacity, and were positively correlated with residual volume (RV), total lung capacity (TLC) and RV/TLC values. In lung tissue and bronchoalveolar lavage fluid samples, MMP-9 and CAP1 expression were inversely related. This relationship was confirmed in HP-AEpiC cells. High expression of MMP-9 and low expression of CAP1 was demonstrated in the COPD group compared with the non-COPD group.

CONCLUSIONS

This study demonstrated an inverse relationship between CAP1 and MMP-9 expression, and high expression of MMP-9 and low expression of CAP1 in those with COPD compared with the non-COPD group. Overexpression of MMP-9 in lung tissue and its interaction with CAP1 is likely to play a major role in airway obstruction in COPD.

Forced expiratory flows' contribution to lung function interpretation in schoolchildren

Forced expiratory flow (FEF) at low lung volumes are supposed to be better at detecting lung-function impairment in asthmatic children than a forced volume. The aim of this study was to examine whether FEF results could modify the interpretation of baseline and post-bronchodilator spirometry in asthmatic schoolchildren in whom forced expiratory volumes are within the normal range. Spirometry, with post-bronchodilator vital capacity within 10% of that of baseline in healthy and asthmatic children, was recorded prospectively. We defined abnormal baseline values expressed as z-scores <-1.645, forced expiratory volume in 1 s (FEV1) reversibility as a baseline increase >12%, FEF reversibility as an increase larger than the 2.5th percentile of post-bronchodilator changes in healthy children. Among 66 healthy and 50 asthmatic schoolchildren, only two (1.7%) children with normal vital capacity and no airways obstruction had abnormal baseline forced expiratory flow at 25-75% of forced vital capacity (FEF25-75%). After bronchodilation, among the 45 asthmatic children without FEV1 reversibility, 5 (11.1%) had an FEF25-75% increase that exceeded the reference interval. Isolated abnormal baseline values or significant post-bronchodilator changes in FEF are rare situations in asthmatic schoolchildren with good spirometry quality.

Electronic monitoring of symptoms and lung function to assess asthma control in children

BACKGROUND

Asthma remains poorly controlled in children. Home monitoring of asthma control may help to improve the level of asthma control.

OBJECTIVES

To compare 2 methods to assess asthma control: (1) prospective home monitoring, based on daily assessment of forced expiratory volume in 1 second (FEV1) and electronic symptom score, and (2) Asthma Control Questionnaire (ACQ) with retrospective assessment of symptoms and FEV1.

METHODS

Ninety-six children with asthma were prospectively followed up during 1 year. Asthma control was assessed by home monitoring, including an electronic symptom score based on Global Initiative for Asthma (GINA) criteria and FEV1 measurements. In the hospital, the ACQ was completed and FEV₁ was measured. Kappa analysis was performed to assess levels of agreement between the 2 methods.

RESULTS

Agreement between the 2 methods was low (κ coefficient of 0.393). In 29 children (37%), prospective home monitoring was less optimistic than the retrospective assessment of asthma control by the ACQ.

CONCLUSION

This study found low agreement between asthma control based on GINA criteria by means of prospective home monitoring and the hospital ACQ. The prospective home monitor detected more cases of less well-controlled asthma than the ACQ. However, optimization of adherence to home monitor use is necessary.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01239238.

Exhaled nitric oxide predicts eosinophilic airway inflammation in COPD

PURPOSE

Chronic obstructive pulmonary disease (COPD) with eosinophilic airway inflammation may represent a unique phenotype, possibly with shared features of COPD and asthma. The role of exhaled nitric oxide (eNO) in identifying COPD patients with sputum eosinophilia was examined in this study.

METHODS

Ninety COPD patients without past medical history of asthma or allergic diseases were prospectively enrolled, and their eNO, lung function, and cellular profile of induced sputum were measured. Eosinophil cationic protein and IgE in sputum and venous blood also were determined. Subjects with and without sputum eosinophilia (>3 %) were compared. The role of eNO in the prediction of sputum eosinophilia was assessed in a logistic regression model.

RESULTS

Patients with sputum eosinophilia had significantly higher levels of eNO (29 vs. 18 ppb, p = 0.01) than those without. The difference in serum total IgE (168 vs. 84.9 IU/ml, p = 0.057) and percentages of positive allergen test results (48.3 vs. 29.5 %, p = 0.082) showed a trend toward significance. The sputum eosinophil level was significantly correlated to the eNO level (r = 0.485, p < 0.001). The eNO level at the cutoff of 23.5 ppb had the maximum sum of sensitivity (62.1 %) and specificity (70.5 %). The unadjusted and adjusted odds ratios of a higher eNO level (>23.5 ppb) in the prediction of sputum eosinophilia were 3.909 (confidence interval (CI) 1.542-9.91, p = 0.004) and 4.329 (CI 1.306-14.356, p = 0.017), respectively.

CONCLUSIONS

eNO is a good marker to identify COPD patients with eosinophilic airway inflammation.

Evaluation of airway responsiveness using colored three-dimensional analyses of a new forced oscillation technique in controlled asthmatic and nonasthmatic children

BACKGROUND

Bronchodilator response (BDR) is routinely used in asthma management. A new forced oscillation technique (FOT) is able to quickly measure respiratory system resistance (Rrs) and reactance (Xrs) at each tidal breath phase. The present study evaluated bronchial changes by using the new FOT.

METHODS

Respiratory resistance and reactance were measured using FOT in 132 children (age, 10.86±4.78 years; M:F=88:44), including asthmatic (n=98) and nonasthmatic children (n=34), pre- and post-bronchodilator inhalation in an asymptomatic state. Whole-breath or within-breath changes in Rrs and Xrs were measured and compared pre- and post-bronchodilator inhalation and between each group. All patients performed spirometry and forced expiratory nitric oxide pre- and post-bronchodilator inhalation.

RESULTS

Spirometric parameters showed significant positive changes at V50 and V25 in both groups; however, these changes were not significantly different between the groups. eNO was significantly higher in the asthmatic group than in the nonasthmatic group; however, there was no significant change pre- and post-inhalation in either group. Rrs in the asthma group was significantly higher in the expiratory phase than in the inspiratory phase. Rrs and Xrs before and after bronchodilator inhalation were significantly different in the asthma group alone, except for the expiratory-inspiratory phase of each of these parameters. Changes in Rrs and Xrs at 5Hz (R5 and X5) in a whole-breath and the inspiratory phase were significantly different between the groups.

CONCLUSIONS

Changes in X5 and R5 reflect bronchial reversibility. The new FOT is useful for asthmatic children.

Bronchodilator responsiveness and reported respiratory symptoms in an adult population

BACKGROUND

The relationship between patient-reported symptoms and objective measures of lung function is poorly understood.

AIM

To determine the association between responsiveness to bronchodilator and respiratory symptoms in random population samples.

METHODS

4669 people aged 40 years and older from 8 sites in Canada completed interviewer-administered respiratory questionnaires and performed spirometry before and after administration of 200 ug of inhaled salbutamol. The effect of anthropometric variables, smoking exposure and doctor-diagnosed asthma (DDA) on bronchodilator responsiveness in forced expiratory volume in 1 second (FEV1) and in forced vital capacity (FVC) were evaluated. Multiple logistic regression was used to test for association between quintiles of increasing changes in FEV1 and in FVC after bronchodilator and several respiratory symptoms.

RESULTS

Determinants of bronchodilator change in FEV1 and FVC included age, DDA, smoking, respiratory drug use and female gender [p<0.005 to p<0.0001 ]. In subjects without doctor-diagnosed asthma or COPD, bronchodilator response in FEV1 was associated with wheezing [p for trend<0.0001], while bronchodilator response for FVC was associated with breathlessness. [p for trend <0.0001].

CONCLUSIONS

Bronchodilator responsiveness in FEV1 or FVC are associated with different respiratory symptoms in the community. Both flow and volume bronchodilator responses are useful parameters which together can be predictive of both wheezing and breathlessness in the general population.

Bronchodilator responses after methacholine and adenosine 5'-monophosphate (AMP) challenges in children with asthma: their relationships with eosinophil markers

BACKGROUND

Bronchodilator responsiveness (BDR) and eosinophilic inflammation are characteristic features of asthma. Objective. The aim of this study was to compare the relationships of BDR after methacholine challenge or adenosine 5'-monophosphate (AMP) challenge to blood eosinophil markers in children with asthma.

METHODS

Methacholine and AMP challenges were performed on 69 children with mild intermittent to moderate persistent asthma. BDR was calculated as the change in forced expiratory volume in 1 second, expressed as percentage change of the value immediately after the each challenge and the value after inhalation of salbutamol. Serum total IgE levels, blood eosinophil counts, and serum eosinophil cationic protein (ECP) levels were determined for each subject.

RESULTS

A positive relationship between serum total IgE levels and BDR was found only after the AMP challenge (R(2) = 0.345, p = .001) rather than after the methacholine challenge (R(2) = 0.007, p = .495). Peripheral blood eosinophil counts correlated more significantly with BDR after AMP challenge (R(2) = 0.212, p = .001) than BDR after methacholine challenge (R(2) = 0.002, p = .724). Both BDR after methacholine challenge (R(2) = 0.063, p = .038) and BDR after AMP challenge (R(2) = 0.192, p = .001) were significantly correlated with serum ECP levels.

CONCLUSION

BDR after AMP challenge may be more closely related to eosinophilic inflammation, compared with that after methacholine challenge.

Worldwide patterns of bronchodilator responsiveness: results from the Burden of Obstructive Lung Disease study

RATIONALE

Criteria for a clinically significant bronchodilator response (BDR) are mainly based on studies in patients with obstructive lung diseases. Little is known about the BDR in healthy general populations, and even less about the worldwide patterns.

METHODS

10 360 adults aged 40 years and older from 14 countries in North America, Europe, Africa and Asia participated in the Burden of Obstructive Lung Disease study. Spirometry was used before and after an inhaled bronchodilator to determine the distribution of the BDR in population-based samples of healthy non-smokers and individuals with airflow obstruction.

RESULTS

In 3922 healthy never smokers, the weighted pooled estimate of the 95th percentiles (95% CI) for bronchodilator response were 284 ml (263 to 305) absolute change in forced expiratory volume in 1 s from baseline (ΔFEV(1)); 12.0% (11.2% to 12.8%) change relative to initial value (%ΔFEV(1i)); and 10.0% (9.5% to 10.5%) change relative to predicted value (%ΔFEV(1p)). The corresponding mean changes in forced vital capacity (FVC) were 322 ml (271 to 373) absolute change from baseline (ΔFVC); 10.5% (8.9% to 12.0%) change relative to initial value (ΔFVC(i)); and 9.2% (7.9% to 10.5%) change relative to predicted value (ΔFVC(p)). The proportion who exceeded the above threshold values in the subgroup with spirometrically defined Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 2 and higher (FEV(1)/FVC <0.7 and FEV(1)% predicted <80%) were 11.1%, 30.8% and 12.9% respectively for the FEV(1)-based thresholds and 22.6%, 28.6% and 22.1% respectively for the FVC-based thresholds.

CONCLUSIONS

The results provide reference values for bronchodilator responses worldwide that confirm guideline estimates for a clinically significant level of BDR in bronchodilator testing.

Reversibility of airway obstruction vs bronchodilatation: do we speak the same language?

Airway reversibility test (or bronchodilatation test) is performed routinely in the diagnosis of obstructive lung diseases. The results of this test may be helpful in the diagnosis and differential diagnosis of asthma and chronic obstructive pulmonary disease (COPD), but sometimes bring confusion. Unfortunately, the nomenclature used for test result is not uniform, which also leads to confusion. Next the reader will find an attempt to order the state of affairs and the introduction of a uniform nomenclature, which would be consistent with the logic and allow for unambiguous classification of reversibility test results to facilitate future decisions based on the differential diagnosis.

Efeito do broncodilatador no tempo de apneia voluntária máxima em pacientes com distúrbios ventilatórios obstrutivos

OBJETIVO: Identificar o papel do broncodilatador no tempo de apneia voluntária máxima em pacientes com distúrbios ventilatórios obstrutivos (DVOs). MÉTODOS: Estudo caso-controle incluindo pacientes com DVOs e grupo controle. Foram realizadas espirometrias antes e após o uso de broncodilatador, assim como testes de apneia respiratória, utilizando-se um microprocessador eletrônico e um pneumotacógrafo como transdutor de fluxo. As curvas de fluxo respiratório foram exibidas em tempo real em um computador portátil, e os tempos de apneia voluntária inspiratória e expiratória máximos (TAVIM e TAVEM, respectivamente) foram determinados a partir do sinal adquirido. RESULTADOS: Um total de 35 pacientes com DVOs e 16 controles foram incluídos no estudo. O TAVIM sem o uso de broncodilatador foi significativamente menor no grupo DVO que no grupo controle (22,27 ± 11,81 s vs. 31,45 ± 15,73; p = 0,025), mas essa diferença não foi significativa após o uso de broncodilatador (24,94 ± 12,89 s vs. 31,67 ± 17,53 s). Os valores de TAVEM foram significativamente menores no grupo DVO que no grupo controle antes (16,88 ± 6,58 s vs. 22,09 ± 7,95 s; p = 0,017) e após o uso de broncodilatador (21,22 ± 9,37 s vs. 28,53 ± 12,46 s; p = 0,024). CONCLUSÕES: Estes resultados fornecem uma evidência adicional da utilidade clínica do teste de apneia na avaliação da função pulmonar e do papel do broncodilatador nesse teste.

Assessment of bronchodilator responsiveness following methacholine-induced bronchoconstriction in children with asthma

Purpose

The aim of this study was to investigate bronchodilator responsiveness (BDR) following methacholine-induced bronchoconstriction and to determine differences in BDR according to clinical parameters in children with asthma.

Methods

The methacholine challenge test was performed in 145 children with mild to moderate asthma, and the provocative concentration causing a 20% decline in FEV1 (PC20) was determined. Immediately after the challenge test, patients were asked to inhale short-acting β2-agonists (SABAs) to achieve BDR, which was assessed as the change in FEV1% predicted×100/post-methacholine FEV1% predicted. For each subject, the asthma medication, blood eosinophil count, serum total IgE, serum eosinophil cationic protein level, and skin prick test result were assessed.

Results

The FEV1 (mean±SD) values of the 145 patients were 90.5±10.9% predicted, 64.2±11.5% predicted, and 86.2±11.2% predicted before and after methacholine inhalation, and following the administration of a SABA, respectively. The BDR did not differ significantly according to asthma medication, age, or gender. However, BDR in the atopy group (37.4±17.7%) was significantly higher than that in the non-atopy group (30.5±10.7%; P=0.037). Patients with blood eosinophilia (38.6±18.1%) displayed increased BDR compared with patients without eosinophilia (32.0±13.8%; P=0.037).

Conclusions

In children with mild to moderate asthma, the responsiveness to short-acting bronchodilators after methacholine-induced bronchoconstriction was not related to asthma medication, but was higher in children with atopy and/or peripheral blood eosinophilia.

The optimization of the diagnostic work-up in patients with suspected obstructive lung disease

Background

Pulmonary function testing is a key procedure in the work-up of patients who are suspected of having asthma and chronic obstructive lung disease (COPD). Therein, clinical visits and pulmonary function tests (PFTs) are the major contributors to the overall financial costs.

The aim of this study was to assess whether a specific diagnostic test protocol contributes to the optimization of the work-up of patients who are suspected of having asthma and COPD.

Methods

A prospective, single-blind, and randomized controlled study was performed. In the control group (CG), all of the PFTs that were ordered by the lung specialist were carried out. In the experimental group (EG), specific PFTs were selected according to our protocol. The primary end point was the total cost of achieving a final diagnosis.

Results

One hundred and seventy-nine patients were included into this study: 86 in the CG and 93 in the EG. The mean number of tests to diagnosis was 3.8 in the CG versus 2.9 in the EG (P < 0.001). The mean number of redundant PFTs before diagnosis was 1.2 in the CG versus 0.08 in the EG (P < 0.001). The number of patients who required an additional outpatient visit to complete diagnosis was higher in the CG in comparison to the EG (P = 0.02). The mean cost of work-up per diagnosis was €227 in the CG versus €181 in the EG (P < 0.001).

Conclusions

In this group of patients with suspected obstructive lung disease, protocol-driven, PFT-based selection is more cost-effective than test selection at the discretion of lung physicians.

Oral complementary medicine and alternative practitioner use varies across chronic conditions and attitudes to risk

OBJECTIVES

To determine whether chronic conditions and patient factors, such as risk perception and decision-making preferences, are associated with complementary medicine and alternative practitioner use in a representative longitudinal population cohort.

PARTICIPANTS AND SETTING

Analysis of data from Stage 2 of the North West Adelaide Health Study of 3161 adults who attended a study clinic visit in 2004-2006. The main outcome measures were the medications brought by participants to the study clinic visit, chronic health conditions, attitudes to risk, levels of satisfaction with conventional medicine, and preferred decision-making style.

RESULTS

At least one oral complementary medicine was used by 27.9% of participants, and 7.3% were visiting alternative practitioners (naturopath, osteopath). Oral complementary medicine use was significantly associated with arthritis, osteoporosis, and mental health conditions, but not with other chronic conditions. Any pattern of complementary medicine use was generally significantly associated with female gender, age at least 45 years, patient-driven decision-making preferences (odds ratio [OR] 1.38, 95% confidence interval [CI]: 1.08-1.77), and frequent general practitioner visits (>five per year; OR 3.62, 95% CI: 2.13-6.17). Alternative practitioner visitors were younger, with higher levels of education (diploma/trade [OR 1.88, 95% CI: 1.28-2.76], bachelor's degree [OR 1.77, 95% CI: 1.11-2.82], income >$80,000 (OR 2.28, 95% CI: 1.26-4.11), female gender (OR 3.15, 95% CI: 2.19-4.52), joint pain not diagnosed as arthritis (OR 1.68, 95% CI: 1.17-2.41), moderate to severe depressive symptoms (OR 2.15, 95% CI: 1.04-4.46), and risk-taking behavior (3.26, 1.80-5.92), or low-to-moderate risk aversion (OR 2.08, 95% CI: 1.26-4.11).

CONCLUSION

Although there is widespread use of complementary medicines in the Australian community, there are differing patterns of use between those using oral complementary medicines and those using alternative practitioners.

Structural lung changes, lung function, and non-invasive inflammatory markers in cystic fibrosis

Cystic fibrosis (CF) lung disease is characterized by chronic airway inflammation and recurrent infections, resulting in (ir)reversible structural lung changes and a progressive decline in lung function. The objective of this study was to investigate the relationship between non-invasive inflammatory markers (IM) in exhaled breath condensate (EBC), lung function indices and structural lung changes, visualized by high resolution computed tomography (HRCT) scans in CF. In 34 CF patients, lung function indices (forced expiratory volume in 1 s, forced vital capacity [FVC], residual volume, and total lung capacity [TLC]) and non-invasive IM (exhaled nitric oxide, and condensate acidity, nitrate, nitrite, 8-isoprostane, hydrogen peroxide, interferon-gamma) were assessed. HRCT scans were scored in a standardized and validated way, a composite score and component scores were calculated. In general, the correlations between non-invasive IM and structural lung changes, and between IM and lung function were low (correlation coefficients <0.40). Patients with positive sputum Pseudomonas cultures had higher EBC nitrite levels and higher parenchymal HRCT subscores than patients with Pseudomonas-negative cultures (p < 0.05). Multiple linear regression models demonstrated that FVC was significantly predicted by hydrogen peroxide in EBC, and the scores of bronchiectasis and mosaic perfusion (Pearson correlation coefficient R = 0.78, p < 0.001). TLC was significantly predicted by 8-isoprostane, nitrate, hydrogen peroxide in EBC, and the mucous plugging subscore (R = 0.92, p < 0.01). Static and dynamic lung function indices in this CF group were predicted by the combination of non-invasive IM in EBC and structural lung changes on HRCT imaging. Future longitudinal studies should reveal whether non-invasive monitoring of airway inflammation in CF adds to better follow-up of patients.

Associations of physical and mental health problems with chronic cough in a representative population cohort

BACKGROUND

Although chronic cough is a common problem in clinical practice, data on the prevalence and characteristics of cough in the general population are scarce. Our aim was to determine the prevalence of chronic cough that is not associated with diagnosed respiratory conditions and examine the impact on health status and psychological health, in a representative adult population cohort

METHODS

North West Adelaide Health Study (n stage 1 = 4060, stage 2 = 3160) is a representative population adult cohort. Clinical assessment included spirometry, anthropometry and skin tests. Questionnaires assessed demographics, lifestyle risk factors, quality of life, mental health and respiratory symptoms, doctor diagnosed conditions and medication use.

RESULTS

Of the 3355 people without identified lung disease at baseline, 18.2% reported chronic cough. In multiple logistic regression models, at follow-up, dry chronic cough without sputum production was significantly more common in males (OR 1.5, 95% CI 1.1, 1.9), current smokers (OR 4.9, 95% CI 3.4, 7.2), obesity (OR 1.9, 95% CI 1.3, 2.9), use of ACE inhibitors (OR 1.8, 95% CI 1.1, 2.9), severe mental health disturbance (OR 2.1, 95% CI 1.4, 3.1) and older age (40-59 years OR 1.7 95% CI 1.2, 2.4; > or = 60 years OR 2.1 95% CI 1.3, 3.5). Among non-smokers only, all cough was significantly more common in men, those with severe mental health disturbance and obesity.

CONCLUSIONS

Chronic cough is a major cause of morbidity. Attention to cough is indicated in patients with obesity, psychological symptoms or smokers. Inquiring about cough in those with mental health problems may identify reversible morbidity.

Diagnosis and management of asthma in older adults

Despite comprehensive guidelines established by the European Global Initiative for Asthma and the U.S. National Asthma Education and Prevention Program on the diagnosis and management of asthma, its mortality in older adults continues to rise. Diagnostic and therapeutic problems contribute to older patients being inadequately treated. The diagnosis of asthma rests on the history and characteristic pulmonary function testing (PFT) with the demonstration of reversible airway obstruction, but there are unique problems in performing this test in older patients and in its interpretation. This review aims to address the difficulties in performing and interpreting PFT in older patients because of the effects of age-related changes in lung function on respiratory physiology. The concept of "airway remodeling" resulting in "fixed obstructive" PFT and the relevance of atopy in older people with asthma are assessed. There are certain therapeutic issues unique to older patients with asthma, including the increased probability of adverse effects in the setting of multiple comorbidities and issues surrounding effective drug delivery. The use of beta 2-agonist, anticholinergic, corticosteroid, and anti-immunoglobulin E treatments are discussed in the context of these therapeutic issues.

Clinical predictors and outcomes of consistent bronchodilator response in the childhood asthma management program

BACKGROUND

Among asthmatic subjects, bronchodilator response (BDR) to inhaled beta(2)-adrenergic agonists is variable, and the significance of a consistent response over time is unknown.

OBJECTIVE

We assessed baseline clinical variables and determined the clinical outcomes associated with a consistently positive BDR over 4 years in children with mild-to-moderate persistent asthma.

METHODS

In the 1041 participants in the Childhood Asthma Management Program, subjects with a change in FEV(1) of 12% or greater (and 200 mL) after inhaled beta(2)-agonist administration at each of their yearly follow-up visits (consistent BDR) were compared with those who did not have a consistent BDR.

RESULTS

We identified 52 children with consistent BDRs over the 4-year trial. Multivariable logistic regression modeling demonstrated that lower baseline prebronchodilator FEV(1) values (odds ratio, 0.71; P < .0001), higher log10 IgE levels (odds ratio, 1.97; P = .002), and lack of treatment with inhaled corticosteroids (odds ratio, 0.31; P = .009) were associated with a consistent BDR. Individuals who had a consistent BDR had more hospital visits (P = .007), required more prednisone bursts (P = .0007), had increased nocturnal awakenings caused by asthma (P < .0001), and missed more days of school (P = .03) than nonresponders during the 4-year follow-up.

CONCLUSIONS

We have identified predictors of consistent BDR and determined that this phenotype is associated with poor clinical outcomes.

Argument for changing criteria for bronchodilator responsiveness

BACKGROUND

Extensively used current guidelines of the American Thoracic Society/European Respiratory Society (ATS/ERS) define a positive aerosolized bronchodilator (BD) response as: "...an increase in FEV(1) and/or FVC > or = 12% of control and > or = 200 mL." We hypothesized that BD responsiveness was better assessed using a statistical approach, linked to each individual's spirometric measurements, rather than the variability of others.

DESIGN

We retrospectively analyzed 1-year's pre- and post-BD spirometric tests from our hospital's clinical laboratory. Using measurements of forced expiratory volume in 1-s (FEV(1)), forced expiratory volume in 3-s (FEV(3)), and forced vital capacity (FVC) from each of three satisfactory forced pre-BD and three satisfactory forced post-BD spirometric maneuvers, we classified each of 313 consecutive patient studies as responders or non-responders in two ways. First, we used ATS/ERS guideline criteria based on population variability. Second, we used unpaired, single-tailed t-tests at P<0.05 for FEV(1), FEV(3), and FVC, considering the variability of and difference between each individual's pre- and post-BD maneuvers.

RESULTS

135 studies were both ATS/ERS and t-test non-responders, three were ATS/ERS responders and t-test non-responders, 86 were ATS/ERS and t-test responders, and 89 were ATS/ERS non-responders and t-test responders. The latter 89 included many patients with either low baseline FEV(1) (< 1.50 L) who could not reach the 200 mL increase criterion or high baseline FEV(1) (> 3.00 L) who could not reach the 12% increase criterion.

CONCLUSIONS

We believe individual t-tests may categorize patient's BD responsiveness better than ATS/ERS guideline criteria which are based on population responses and require both fixed volume and percentage changes. Its usefulness by others remains to be shown.

Population pharmacodynamic model of bronchodilator response to inhaled albuterol in children and adults with asthma

BACKGROUND

Because interpatient variability in bronchodilation from inhaled albuterol is large and clinically important, we characterized the albuterol dose/response relationship by pharmacodynamic modeling and quantified variability.

METHODS

Eighty-one patients with asthma (24% African American [AA]; 8 to 65 years old; baseline FEV1, 40 to 80% of predicted) received 180 microg of albuterol from a metered-dose inhaler (MDI), and then 90 microg every 15 min until maximum improvement or 540 microg was administered; all then received 2.5 mg of nebulized albuterol. FEV1 was measured 15 min after each dose. The population cumulative dose/response data were fitted with a sigmoid maximum effect of albuterol (Emax) [maximum percentage of predicted FEV1 effect] model by nonlinear mixed-effects modeling. The influence of covariates on maximum percentage of predicted FEV1 reached after albuterol administration (Rmax) and cumulative dose of albuterol required to bring about 50% of maximum effect of albuterol (ED50) and differences between AA and white patients were explored.

RESULTS

ED50 was 141 microg, and Emax was 24.0%. Coefficients of variation for ED50 and Emax were 40% and 56%, respectively. Ethnicity was a statistically significant covariate (p < 0.05). AA and white patients reached 82.4% and 91.9% of predicted FEV1, respectively (p = 0.0004); and absolute improvement in percentage of predicted FEV1 was 16.6% in AA patients vs 26.7% in white patients (p < 0.0003). There were no baseline characteristic differences between AA and white patients. Nebulized albuterol increased FEV1 > or = 200 mL in 21% of participants. Heart rate and BP were unchanged from baseline after maximal albuterol doses.

CONCLUSIONS

Our model predicts that 180 microg of albuterol by MDI produces a 14.4% increase in percentage of predicted FEV1 over baseline (11.7% in AA patients, and 17.5% in white patients). Emax varies widely between asthmatic patients. AA patients are less responsive to maximal doses of inhaled albuterol than white patients.

FEV1 response to bronchodilation in an adult urban population

BACKGROUND

Most studies evaluating bronchodilation in flow-volume spirometry have been conducted in patients with obstructive airways diseases, but less is known about bronchodilation responses in the general population or in healthy subjects.

METHODS

We evaluated an urban population sample of 628 adults (260 men, 368 women) aged 25 to 74 years with flow-volume spirometry using inhalation of 0.4 mg of a salbutamol aerosol with a spacer device for bronchodilation. On the basis of a structured interview, a subgroup of 219 healthy, asymptomatic nonsmokers was selected.

RESULTS

In the population sample, the average increase in FEV(1) from baseline after salbutamol inhalation was 77.2 mL (SD, 109.7 mL) or 2.5% (SD, 3.9%). In healthy asymptomatic nonsmokers, the mean change in FEV(1) was 62.0 mL (SD, 89.7 mL) or 1.8% (SD, 2.6%). In the whole population, the 95th percentile limit of the increase in FEV(1) was 8.5%, while it was 5.9% among healthy asymptomatic nonsmokers. The absolute change in FEV(1) correlated significantly with baseline FVC (p < 0.01). The FEV(1)/FVC ratio at baseline was the strongest influencing factor for the bronchodilation response.

CONCLUSIONS

The results indicate that a significant increase in FEV(1) from baseline in a bronchodilation test is around 9% in an urban population. The level of the significant absolute increase in FEV(1) seems to depend on FVC. Low baseline FEV(1)/FVC ratio, reflecting airflow limitation, is the strongest determinant for FEV(1) response to bronchodilation.

[Which definition to use when defining reversibility of airway obstruction?]

INTRODUCTION

There is no clear consensus about what constitutes reversibility of airway obstruction. European Respiratory Society (ERS): Increase in FEV1 and/or FVC>12% of their theoretical value and>0.2l. British Thoracic Society: FEV1>15% of initial value and FEV1>0.2l. Global Initiative for Chronic Obstructive Lung Disease: Increase in FEV1>12% and>0.2l. Australia and New Zealand Thoracic Society: Increase in FEV1 >15%. American Thoracic Society/ERS: Increase in FEV1>12% and>0.2l or increase in FVC>12% and 0.2l. Our principal objective was to determine the percentage of patients with COPD (n=62) who were significant responders to the reversibility test according to the 5 recommendations.

METHODS

Plethysmography was performed before and 15 minutes after inhalation of 400 micrograms of a short acting bronchodilator (BD). COPD is defined as a FEV1/FVC post BD<0.7.

RESULTS

The percentage of responders varied from 24% to 50% depending on the recommendations used.

CONCLUSION

Reversibility of airway obstruction is recommendation dependent.

Not all children with under-control asthma are controlled

Subclinical lung function alterations can sometimes be discovered in asthmatic patients under clinical control. This study aimed to identify the burden of asthmatic children with subclinical airways abnormalities who may benefit from an adjustment in asthma therapy. 134 6-to-17-year-old asthmatic children were enrolled. Of them, 98 presented apparently under clinical control disease and all performed spirometry before and after bronchodilation: 17 (17.3%) had a positive bronchodilation test, in addition to significantly lower lung function indexes as compared to those with under-control asthma who had a negative bronchodilation test. These patients were randomized and re-evaluated: patients (n=8) receiving an adjustment in their therapy showed an improvement in lung function tests and quality of life indexes as compared to 7 without therapy adjustment. In conclusion, a substantial number of apparently-under-control asthmatic children show airways alterations that can be improved by adjusting their therapy, which also seems to enhance their quality of life.