Provocative Concentration Of Methacholine Research Articles

Anticipating undiagnosed asthma in symptomatic adults with normal pre- and post-bronchodilator spirometry: a decision tool for bronchial challenge testing

BackgroundSome patients with asthma demonstrate normal spirometry and remain undiagnosed without further testing.ObjectiveTo determine clinical predictors of asthma in symptomatic adults with normal spirometry, and to generate a tool to help clinicians decide who should undergo bronchial challenge testing (BCT).MethodsUsing random-digit dialling and population-based case-finding, we recruited adults from the community with respiratory symptoms and no previous history of diagnosed lung disease. Participants with normal pre- and post-bronchodilator spirometry subsequently underwent BCT. Asthma was diagnosed in those with symptoms and a methacholine provocative concentration (PC20) of < 8 mg/ml. Sputum and blood eosinophils, and exhaled nitric oxide were measured. Univariate analyses identified potentially predictive variables, which were then used to construct a multivariable logistic regression model to predict asthma. Model sensitivity, specificity, and area under the receiver operating curve (AUC) were calculated.ResultsOf 132 symptomatic individuals with normal spirometry, 34 (26%) had asthma. Of those ultimately diagnosed with asthma, 33 (97%) answered ‘yes’ to a question asking whether they experienced cough, chest tightness or wheezing provoked by exercise or cold air. Other univariate predictors of asthma included female sex, pre-bronchodilator FEV1 percentage predicted, and percent positive change in FEV1 post bronchodilator. A multivariable model containing these predictive variables yielded an AUC of 0.82 (95% CI: 0.72–0.91), a sensitivity of 82%, and a specificity of 66%. The model was used to construct a nomogram to advise clinicians which patients should be prioritized for BCT.ConclusionsFour readily available patient characteristics demonstrated a high sensitivity and AUC for predicting undiagnosed asthma in symptomatic adults with normal pre- and post-bronchodilator spirometry. These characteristics can potentially help clinicians to decide which individuals with normal spirometry should be investigated with bronchial challenge testing. However, further prospective validation of our decision tool is required.

Concentration-dependent alterations in the human plasma proteome following controlled exposure to diesel exhaust

Traffic-related air pollution (TRAP) exposure is associated with systemic health effects, which can be studied using blood-based markers. Although we have previously shown that high TRAP concentrations alter the plasma proteome, the concentration-response relationship between blood proteins and TRAP is unexplored in controlled human exposure studies. We aimed to identify concentration-dependent plasma markers of diesel exhaust (DE), a model of TRAP. Fifteen healthy non-smokers were enrolled into a double-blinded, crossover study where they were exposed to filtered air (FA) and DE at 20, 50 and 150 μg/m3 PM2.5 for 4h, separated by ≥ 4-week washouts. We collected blood at 24h post-exposure and used label-free mass spectrometry to quantify proteins in plasma. Proteins exhibiting a concentration-response, as determined by linear mixed effects models (LMEMs), were assessed for pathway enrichment using WebGestalt. Top candidates, identified by sparse partial least squares discriminant analysis and LMEMs, were confirmed using enzyme-linked immunoassays. Thereafter, we assessed correlations between proteins that showed a DE concentration-response and acute inflammatory endpoints, forced expiratory volume in 1 s (FEV1) and methacholine provocation concentration causing a 20% drop in FEV1 (PC20). DE exposure was associated with concentration-dependent alterations in 45 proteins, which were enriched in complement pathways. Of the 9 proteins selected for confirmatory immunoassays, based on complementary bioinformatic approaches to narrow targets and availability of high-quality assays, complement factor I (CFI) exhibited a significant concentration-dependent decrease (−0.02 μg/mL per μg/m3 of PM2.5, p = 0.04). Comparing to FA at discrete concentrations, CFI trended downward at 50 (−2.14 ± 1.18, p = 0.08) and significantly decreased at 150 μg/m3 PM2.5 (−2.93 ± 1.18, p = 0.02). CFI levels were correlated with FEV1, PC20 and nasal interleukin (IL)-6 and IL-1β. This study details concentration-dependent alterations in the plasma proteome following DE exposure at concentrations relevant to occupational and community settings. CFI shows a robust concentration-response and association with established measures of airway function and inflammation.

The Effect of Zingiber cassumunar (Phlai Capsule) on Bronchial Hyperresponsiveness in Asthmatic Patients: A Randomized Controlled Trial

Background: Bronchial hyperresponsiveness (BHR) is a key feature of asthma. Compound D, an active compound in Phlai, can bind cysteinyl leukotrienes receptors that play a role for asthma treatment. Objective: To determine the effect of Phlai capsules on BHR measured by the methacholine challenge test. Materials and Methods: A randomized, double-blind, placebo-controlled, crossover study was conducted in adult asthmatic patients with partly controlled symptoms. Each patient received four weeks of treatment with either Phlai or placebo separated by a 2-week washout period. The main outcome was provocative concentration of methacholine causing a 20% drop in FEV₁ (PC₂₀). Asthma control test (ACT) scores, and fractional exhaled nitric oxide (FeNO) levels were secondary end points. Results: Thirty patients were randomly allocated to either the Phlai or the placebo group. All patients had allergic rhinitis and received inhaled corticosteroid and long-acting beta2-agonist (ICS/LABA) or ICS alone. Four weeks after treatment, mean PC₂₀ in the Phlai group was higher than in the placebo group at 9.76±1.56 mg/mL versus 6.05±1.65 mg/mL (p=0.151). The improvement of ACT scores in the Phlai group was significantly higher than in the placebo group. FeNO levels decreased after treatment in the Phlai group. All patients tolerated the treatment well and had no side effects. Conclusion: In adult asthmatic patients with partly controlled symptoms, concomitant treatment with Phlai capsules tended to decrease BHR and significantly improve symptom scores. Keywords: Asthma; Asthma control test; Bronchial hyperresponsiveness; Zingiber cassumunar; Phlai

Development and validation of a predictive model combining patient-reported outcome measures, spirometry and exhaled nitric oxide fraction for asthma diagnosis.

Although asthma is a common disease, its diagnosis remains a challenge in clinical practice with both over- and underdiagnosis. Here, we performed a prospective observational study investigating the value of symptom intensity scales alone or combined with spirometry and exhaled nitric oxide fraction (F ENO) to aid in asthma diagnosis. Over a 38-month period we recruited 303 untreated patients complaining of symptoms suggestive of asthma (wheezing, dyspnoea, cough, sputum production and chest tightness). The whole cohort was split into a training cohort (n=166) for patients recruited during odd months and a validation cohort (n=137) for patients recruited during even months. Asthma was diagnosed either by a positive reversibility test (≥12% and ≥200 mL in forced expiratory volume in 1 s (FEV1)) and/or a positive bronchial challenge test (provocative concentration of methacholine causing a 20% fall in FEV1 ≤8 mg·mL-1). In order to assess the diagnostic performance of symptoms, spirometric indices and F ENO, we performed receiver operating characteristic curve analysis and multivariable logistic regression to identify the independent factors associated with asthma in the training cohort. Then, the derived predictive models were applied to the validation cohort. 63% of patients in the derivation cohort and 58% of patients in the validation cohort were diagnosed as being asthmatic. After logistic regression, wheezing was the only symptom to be significantly associated with asthma. Similarly, FEV1 (% pred), FEV1/forced vital capacity (%) and F ENO were significantly associated with asthma. A predictive model combining these four parameters yielded an area under the curve of 0.76 (95% CI 0.66-0.84) in the training cohort and 0.73 (95% CI 0.65-0.82) when applied to the validation cohort. Combining a wheezing intensity scale with spirometry and F ENO may help in improving asthma diagnosis accuracy in clinical practice.

Two-minute tidal breathing methacholine bronchial challenge: Comparison of two jet nebulisers.

The American Thoracic Society (ATS) guideline for methacholine challenge testing (MCT) recommended using the English Wright (EW) nebuliser. However, other brands of nebulisers are also indicated to be acceptable for this technique, but further validation of nebuliser performance is recommended. To compare the methacholine provocation concentration causing a 20% fall in forced expiratory volume in 1 second (PC20 -FEV1 ) measured by using EW nebuliser and DV 646 nebuliser. Subjects were randomly assigned to undergo 2-min tidal breathing methacholine challenge with either EW or DV 646 nebuliser on two separate days, which were at least 24 hours but not more than 7 days apart. The above procedure was repeated for each subject in 1 month, but the nebulisers were selected in a reverse order. The study includes 15 mild and stable asthmatic patients. The geometric means (SD) of methacholine PC20 measured with using EW and DV 646 nebulisers were 1.82 (6.38) mg/mL versus 0.83 (1.82) mg/mL, respectively in the initial two visits and 2.56 (6.29) mg/mL versus 0.78 (1.40) mg/mL in the following two visits (both P < 0.05). There are well correlations between PC20-EW1 and PC20-EW2 (r=0.99, P<0.01), PC20-DV1 and PC20-DV2 (r=0.88, P<0.01), and between PC20-EW1 and PC20-DV1 (r=0.91, P<0.01), PC20-EW2 and PC20-DV2 (r=0.78, P<0.01). PC20 -FEV1 measured by using the two conventional jet nebulisers was both repeatable and the results were highly correlated.

Current Asthma Prevalence Using Methacholine Challenge Test in Korean Children from 2010 to 2014.

BackgroundMost epidemiological studies depend on the subjects' response to asthma symptom questionnaires. Questionnaire-based study for childhood asthma prevalence may overestimate the true prevalence. The aim of this study was to investigate the prevalence of “Current asthma” using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and methacholine challenge test in Korean children.MethodsOur survey on allergic disease included 4,791 children (age 7–12 years) from 2010 to 2014 in Korean elementary schools. Bronchial hyperresponsiveness (BHR) was defined as provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (FEV1) (PC20) ≤ 16 mg/mL. “Current asthma symptoms” was defined as positive response to “Wheezing, current,” “Treatment, current,” or “Exercise, current.” “Current asthma” was defined when the subjects with “Current asthma symptoms” showed BHR on the methacholine challenge test or had less than 70% of predicted FEV1 value.ResultsThe prevalence of “Wheezing, ever,” “Wheezing, current,” “Diagnosis, ever,” “Treatment, current,” “Exercise, current,” and “Current asthma symptoms” was 19.6%, 6.9%, 10.0%, 3.3%, 3.5%, and 9.6%, respectively, in our cross-sectional study of Korean elementary school students. The prevalence of BHR in elementary school students was 14.5%. The prevalence of BHR in children with “Wheezing, ever,” “Wheezing, current,” “Diagnosis, ever,” “Treatment, current,” and “Exercise, current” was 22.3%, 30.5%, 22.4%, 28.8%, and 29.9%, respectively. BHR was 26.1% in those with “Current asthma symptoms.” The prevalence of “Current asthma” was 2.7%.ConclusionsOur large-scale study provides 2.7% prevalence of current asthma in Korean elementary school children. Since approximately one third of the children who have “Current asthma symptoms” present BHR, both subjective and objective methods are required to accurately predict asthma in subjects with asthma symptoms.

Evaluation of Fractional Exhaled Nitric Oxide in Pediatric Asthma and Allergic Rhinitis.

Fractional exhaled nitric oxide (FeNO) is a non-invasive test for evaluating the degree of airway inflammation and for the diagnosis, evaluation, and treatment of asthma. We attempted to measure FeNO levels in Korean children with asthma and determine its cutoff value for diagnosing asthma. We enrolled 176 children and adolescents between the ages of 5 and 18 years, who visited for the evaluation of chronic cough, shortness of breath, and wheezing. Among them, 138 patients who underwent skin prick tests or inhalation Immuno CAP (UniCAP; Pharmacia, Uppsala, Sweden) tests for allergy testing together with a pulmonary function test were included. FeNO was measured using a NIOX MINO (Aerocrine AB, Solna, Sweden) instrument according to the American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines. There were 29 patients with asthma, 43 with rhinitis, and 38 with asthma and allergic rhinitis. In the asthma group, FeNO levels significantly correlated with total immunoglobulin E (r = 0.572, p < 0.001), but did not show significant correlation with pulmonary function test parameters (forced vital capacity—FVC, forced expiratory volume in one second—FEV1, FEV1/FVC) or PC20 (provocative concentration of methacholine causing a 20% fall in FEV1). The FeNO cutoff values obtained in the asthma and asthma rhinitis groups were 16.5 ppb and 18.5 ppb, respectively. Hence, we provide a FeNO cutoff value according to the presence or absence of rhinitis in pediatric patients with asthma.

Performance Characteristics of Spirometry With Negative Bronchodilator Response and Methacholine Challenge Testing and Implications for Asthma Diagnosis

In patients with a history suggestive of asthma, diagnosis is usually confirmed by spirometry with bronchodilator response (BDR) or confirmatory methacholine challenge testing (MCT). We examined the proportion of participants with negative BDR testing who had a positive MCT (and its predictors) result and characteristics of MCT, including effects of controller medication tapering and temporal variability (and predictors of MCT result change), and concordance between MCT and pulmonologist asthma diagnosis. Adults with self-reported physician-diagnosed asthma were recruited by random-digit dialing across Canada. Subjects performed spirometry with BDR testing and returned for MCT if testing was nondiagnostic for asthma. Subjects on controllers underwent medication tapering with serial MCTs over 3 to 6weeks. Subjects with a negative MCT (the provocative concentration of methacholine that results in a 20%drop in FEV1 [PC20] > 8mg/mL) off medications were examined by a pulmonologist and had serial MCTs after 6 and 12months. Of 500 subjects (50.5 ± 16.6 years old, 68.0%female) with a negative BDR test for asthma, 215 (43.0%) had a positive MCT. Subjects with prebronchodilator airflow limitation were more likely to have a positive MCT (OR, 1.90; 95%CI, 1.17-3.04). MCT converted from negative to positive, with medication tapering in 18 of 94 (19.1%) participants, and spontaneously over time in 25 of 165 (15.2%) participants. Of 231 subjects with negative MCT, 28 (12.1%) subsequently received an asthma diagnosis from a pulmonologist. In subjects with a self-reported physician diagnosis of asthma, absence of bronchodilator reversibility had a negative predictive value of only 57%to exclude asthma. A finding of spirometric airflow limitation significantly increased chances of asthma. MCT results varied with medication taper and over time, and pulmonologists were sometimes prepared to give a clinical diagnosis of asthma despite negative MCT. Correspondingly, in patients for whom a high clinical suspicion of asthma exists, repeat testing appears to be warranted.

Bronchial Response to High and Low Molecular Weight Occupational Inhalant Allergens.

PurposeOccupational asthma may be induced by high- or low-molecular weight allergens (HMWA or LMWA, respectively). The study was conducted to compare the pattern of bronchial response in 200 HMWA-induced asthmatics (n = 130) and LMWA-induced asthmatics (n = 70).MethodsThe study participants underwent a single-blind, placebo-controlled specific inhalation challenge (SIC) with workplace allergens, accompanied by evaluation of non-specific bronchial hyperresponsiveness (NSBHR) with methacholine before and after the SIC.ResultsA single early bronchial response more frequently occurred in HMWA-induced asthmatics than in LMWA-induced asthmatics (86.2% vs. 20%). An isolated late bronchial response or atypical patterns were more frequently observed in LMWA-induced asthmatics than in LMWA-induced asthmatics (45.7% vs. 3.8% or 34.3% vs. 10%, respectively). Baseline NSBHR before SIC was more often detected in LMWA-induced asthmatics than in HMWA-induced asthmatics (81.4% vs. 54.6%), and the median value of the provocation concentration of methacholine was relevantly lower in these patients before and after SIC. A significant 3-fold increase in NSBHR after SIC was observed more often in LMWA-induced asthmatics than in HMWA-induced asthmatics (82.8% vs. 66.1%). In addition, compared to LMWA-induced asthmatics, HMWA-induced asthmatics were older, were more frequently active smokers, showed lower level of NSBHR, and more frequently continued their work in harmful occupational exposure.ConclusionsThe results of this study suggest that HMWA-induced asthmatics may have milder clinical courses and that there is a possibility of job continuation despite asthma exacerbation requiring medical surveillance.

A high prevalence of airway hyperresponsiveness in cross country skiers

The aim of the study was to evaluate prevalence and age-dependence of bronchial hyperresponsiveness (BHR) in cross country skiers. Methods. Twenty-nine cross-country skiers (14 males, 15 females aged 18 to 30 years; average age, 23.9 ± 3.4 years) were involved in the study. All athletes underwent pulmonary function tests (spirometry before and after inhalation of 400 μg of salbutamol, body plethysmography, diffusion test). Then, methacholine challenge test was performed. Results. In skiers, lung function data were higher compared to the reference vаlues calculated in accordance with the ECSC equations, 1993. Bronchial reversibility was found in 4 athletes (14%). Methacholine provocative concentration causing a 20% fall in FEV1 (PC20) was &gt; 4 mg/ml in 9 skiers (31%). Significant relationships were found between the atheltes’ age and BHR. Conclusion. Cross-country skiers have a high prevalence of BHR to methacholine. BHR increases with age.

Bronchodilation Test with Inhaled Salbutamol Versus Bronchial Methacholine Challenge to Make an Asthma Diagnosis: Do They Provide the Same Information?

Methacholine bronchial challenge and bronchodilation to salbutamol are key tests in clinical practice to make asthma diagnosis. To assess the concordance between the 2 tests and to see whether they actually identify the same population of asthmatics. We conducted a retrospective study using our asthma clinic database to see how methacholine bronchial challenge compared to bronchodilation to salbutamol in untreated patients with recurrent or chronic symptoms suspicious of asthma. We identified 194 untreated patients with baseline forced expiratory volume in 1 second (FEV1) ≥70% predicted who had both a bronchodilation test with salbutamol and a methacholine bronchial challenge 7 to 14 days apart. A positive bronchial challenge was a provocative concentration of methacholine causing a 20% fall in FEV1 ≤16 mg/mL, whereas a positive bronchodilation test was a reversibility to 400 μg inhaled salbutamol ≥12% from baseline and 200 mL. Overall, asthma diagnosis was confirmed in 91% of cases leaving 9% of subjects with double negative tests. Isolated positive methacholine challenge was found in 71% of subjects, double positive tests in 17%, whereas isolated significant bronchodilation to salbutamol was rare (3%). There was no correlation between provocative concentration of methacholine causing a fall in FEV1 of 20% (PC20M) and the magnitude of salbutamol reversibility (P= .10). Baseline FEV1/forced vital capacity ratio inversely correlated with reversibility to salbutamol (P < .001) but not with PC20M (P= .1). No difference was found between the groups regarding demographic and immunoinflammatory features, including the proportion of eosinophilic asthma. We conclude that methacholine challenge outperforms reversibility to salbutamol to diagnose asthma without selecting patients with distinct inflammatory profile. Baseline airway obstruction predicts magnitude of reversibility but not hyperresponsiveness.

Asthma control test reflects not only lung function but also airway inflammation in children with stable asthma

Objective: Various numerical asthma control tools have been developed to distinguish different levels of symptom control. We aimed to examine whether the asthma control test (ACT) is reflective of objective findings such as lung function, fractional exhaled nitric oxide (FeNO) and laboratory data in patients with stable asthma.Methods: We included patients who were enrolled in the Korean Childhood Asthma Study. ACT, spirometry, blood tests and FeNO were performed in patients after stabilization of their asthma. We examined differences among spirometry parameters, blood tests and FeNO according to control status as determined by ACT and investigated for any significant correlations.Results: The study population consisted of 441 subjects. Spirometry showed that forced expiratory volume in one second (FEV1), forced expiratory flow between 25% and 75% of forced vital capacity and FEV1/forced vital capacity were all significantly higher in the controlled asthma group. Likewise, FeNO and percent-change in FEV1 were both significantly lower in the controlled asthma group. In blood tests, the eosinophil fraction was significantly lower in the controlled asthma group while white blood cell count was significantly higher in the controlled asthma group. Lastly, among the various factors analyzed, only provocative concentration of methacholine causing a 20% fall in FEV1 significantly correlated with ACT score.Conclusion: ACT is useful as part of the routine evaluation of asthmatic children and should be used as a complement to existing tools such as spirometry and FeNO measurement.

Bronchoprotective effect of vilanterol against methacholine-induced bronchoconstriction in mild asthmatics: A randomized three-way crossover study

BackgroundUltra-long-acting β2 agonists (uLABA) are relatively new anti-asthma medications of which there are three different formulations currently available: olodaterol, indacaterol, and vilanterol. The first 2 formulations have been shown to exert bronchoprotective effects; they are able to prevent airway smooth muscle contraction on exposure to constricting stimuli. However, studies have found that these 2 drugs produce different degrees and durations of bronchoprotection against methacholine. ObjectiveThe objective of this study was to investigate the degree of bronchoprotection provided by vilanterol against methacholine-induced bronchoconstriction. MethodsFourteen patients with mild-to-moderate asthma (8 male; baseline percent predicted forced expiratory volume in 1 second [FEV1] > 65%; provocative concentration of methacholine causing a 20% reduction in FEV1 [PC20] ≤ 8 mg/mL) completed this randomized, double-blind, 3-way crossover study. Methacholine challenges were performed before treatment administration (placebo, 100 μg fluticasone furoate, or 25 μg vilanterol + 100 μg fluticasone furoate) and at 0.5 and 24 hours posttreatment. Each treatment arm was separated by a minimum 7-day washout period. A combination therapy of vilanterol+fluticasone furoate was used, because vilanterol is not available as a monotherapy. ResultsSignificant bronchoprotection was evident after the combination treatment at both 0.5 and 24 hours with doubling dose shifts in methacholine PC20 of 2.0 (P = .0004) and 1.6 (P = .0001), respectively. Clinically significant bronchodilation was only recorded at 24 hours after combination treatment (P < .05). ConclusionThese findings suggest that vilanterol (in combination with fluticasone furoate) provides significant bronchoprotection against methacholine-induced bronchoconstriction for at least 24 hours in patients with mild-to-moderate asthma. Clinical Trial Registrationclinicaltrials.gov (NCT03315000).

Comparability of methacholine challenge test results between two jet nebulizers

ABSTRACTRATIONALE: To improve standardization of methacholine challenge testing, all nebulizers must be characterized in a manner that allows data comparability between test sites regardless of the protocol or equipment used. In response to issues concerning the highly standardized Wright jet nebulizer, other devices, which may or may not be characterized, have been used for testing. One such device is the Bennett Twin jet nebulizer, which has been assumed to produce equivalent results to the Wright based on a small, unpublished data set.OBJECTIVE: Determine if the Wright and Bennett Twin jet nebulizers produce equivalent methacholine challenge test results.METHODS AND MEASUREMENTS: As an addition to a larger, multi-site study comparing the Wright jet nebulizer and the Aerogen® Solo vibrating mesh nebulizer for standard use in methacholine challenge testing, our test site (n = 20) included a crossover study arm that entailed testing with the Bennett Twin in mild-to-moderate asthmatics. The two jet nebulizer models were calibrated with the same methodology (weight loss of 0.13 g/min) and were operated per the two-minute tidal breathing protocol. Test results in the form of the PC20 (provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second) were compared. MAIN RESULTS: The two jet nebulizer models produced equivalent PC20 results, with geometric mean data of 2.3 mg/mL and 1.8 mg/mL for the Wright and Bennett Twin, respectively.CONCLUSION: These findings suggest that, like the Wright, the Bennett Twin is suitable for standard use in methacholine challenge testing.

Methacholine Challenge Test Reveals a High Prevalence of Subclinical Severe Airway Hyper-Reactivity in Children and Yound Adults with Sickle Cell Disease Which Correlates with Higher Sickle Acute Events and Acute Chest

▪Background: Although increase prevalence of airway hyper-reactivity (AHR) has been detected in children, and even adults with sickle cell disease (SCD) using methacholine provocative challenge test (MCT), AHR was not been found to be associated with clinical asthma.Hence, the clinical implications of AHR in SCD are unknown. Furthermore, AHR studies in SCD patients using MCT lack comparisons with a control population. We recently showed that increased placenta growth factor (PlGF) levels in sickle mice causes AHR by upregulating leukotriene synthesis and inflammation. We therefore designed a prospective study to determine the prevalence of AHR in children and young adults with SCD, and in unaffected siblings living in the same household as a control population, and also determine the biochemical and clinical implications of AHR in SCD.Methods: A total of 67 patients with SCD and 14 unaffected siblings of the patients enrolled on to the study for determining baseline AHR (ClinicalTrials.gov Identifier: NCT00448370). Chief eligibility criteria included a diagnosis of SCD (HbSS, HbSC or HbS b-thalassemia) confirmed by hemoglobin electrophoresis or gene sequencing, ages 5.5 years to 30 years who were able to complete pulmonary function testing and were at baseline/steady state (no acute sickle events 3 weeks prior or acute chest syndrome (ACS) 4 weeks prior). Excluded were patients taking anti-leukotriene medications within 30 days prior, although patients with SCD who had a known history of asthma but not on leukotriene inhibitors were eligible. Patients with chronic transfusions, congenital lung or heart condition, or other medical condition that could affect the pulmonary function testing were also ineligible. Unaffected siblings of the 67 enrolled SCD patients living in the same household were offered enrollment for MCT and those consenting were enrolled.Results: 64 SCD patients and 14 siblings underwent a MCT; 3 of 67 SCD patients had FEV1<70% of predicted at baseline, and therefore, for safety reasons, were not subjected to MCT. The degree of AHR was defined by the provocative concentration of methacholine that resulted in a 20% decline in FEV1 (PC20): no AHR=PC20 >16mg/mL; borderline AHR=PC20 4-16mg/mL; mild AHR=PC20 1-3mg/mL and moderate-severe AHR=PC20 <1mg/mL. All subjects were given a dose of albuterol after completion of MCT. MCT was safe in all subjects, and no AHR or acute sickle events occurred in any subject for three weeks after the MCT. Overall, 25 of 67 (37%) SCD patients had no AHR, 8 of 67 (12%) had borderline AHR (PC20 9±1.4mg/ml), 10 of 67 (15%) had mild AHR (PC20 1.72 ±0.16) and 24 of 67 (36%) had moderate-severe AHR (PC20 0.6 ±0.06). Of unaffected siblings, 10 of 14 (71%) had no AHR, 2 of 14 (14%) had borderline AHR (PC20 10±0.4) and 2 of 14 (14%) had mild AHR (PC20 1.7±0.4). Moderate to severe AHR was only seen in SCD patients and not sibling controls. Severe AHR prevalence was highest in the HbSS group. We analyzed the clinical characteristics of the SCD subjects, including acute sickle episodes, defined as admission for one of the following: pain crises, fever with or without a known source of infection, cough/wheezing/chest pain, impending acute chest syndrome, enlarged and splenic sequestration or priapism. SCD patients with AHR had significantly higher (P<0.05) admissions from acute sickle episodes (2.7±0.1) and acute chest syndrome (1.5±0.15). We next assessed PlGF and leukotriene levels in SCD subjects. PlGF levels were not quantifiable due to presence of hemolysis, which confounds PlGF ELISA. However, we found a trend towards higher (1.3-2 fold) expression of PlGF-induced target genes (VEGF, IL-1β, IL-8, CCL2) in the mononuclear cells of patients with severe AHR; Also, circulating cysteinyl leukotriene D4 levels in their plasma were significantly higher.Conclusions: There was a higher prevalence of mild to severe AHR (51%) in patients with SCD, compared to a 14% prevalence of mild AHR in siblings living in the same household. The higher degree of AHR was associated with increased SCD morbidity - increased rates of admission from ACS and pain crisis, when compared to those with no AHR. AHR was associated with higher leukotrienes and a trend towards higher PlGF target gene induction. Together, our data suggests that AHR may be a biomarker for SCD morbidity, and may also be a therapeutic target, since blockade of PlGF or leukotriene synthesis in patients with severe AHR may reduce SCD morbidity. DisclosuresNo relevant conflicts of interest to declare.

The effect of glycopyrronium and indacaterol, as monotherapy and in combination, on the methacholine dose-response curve of mild asthmatics: a randomized three-way crossover study

BackgroundMethacholine dose-response curves illustrate pharmacologic bronchoprotection against methacholine-induced airway hyperresponsiveness and can be used to quantitate changes in airway sensitivity (position), reactivity (slope), and maximal responsiveness following drug administration. Our objective was to determine the influence of single-dose glycopyrronium (long-acting muscarinic antagonist) and indacaterol (ultra-long acting β2 agonist), as monotherapy and in combination, on the methacholine dose-response curve of mild asthmatics and to compare these findings with a non-asthmatic control curve.MethodsThis was a randomized, double blind, double dummy, three-way crossover study. For asthmatic participants (n = 14), each treatment arm included a baseline methacholine challenge, drug administration, and repeat methacholine challenges at 1, 24, and 48 h. Non-asthmatic control participants (n = 15) underwent a single methacholine challenge and did not receive any study treatment. Methacholine dose-response curves were graphed as the percent fall in forced expiratory volume in 1 s (FEV1) for each methacholine concentration administered. Best-fit curves were then generated. Differences in airway reactivity were calculated through linear regression. Changes in airway sensitivity were assessed as the shift in the provocative concentration of methacholine causing a 20% fall in FEV1.ResultsCompared to baseline, all treatments significantly reduced airway sensitivity to methacholine at 1 h post-dose (indacaterol ~1.5 doubling concentrations; glycopyrronium ~5 doubling concentrations; combination ~5 doubling concentrations). Bronchoprotection at 24 and 48 h remained significant with glycopyrronium and combination therapy only. Airway reactivity was not influenced by indacaterol whereas glycopyrronium significantly reduced airway reactivity at all time-points (p = 0.003-0.027). The combination significantly decreased slope at 1 (p = 0.021) and 24 (p = 0.039) hours only. The non-asthmatic control and 1-h glycopyrronium curves are nearly identical. Only the non-asthmatic control and 1-h post-combination therapy curves appeared to generate a true response plateau (three data points within 5%), which occurred at a 14% fall in FEV1.ConclusionsMethacholine dose-response curves differentiate the bronchoprotective mechanisms triggered by different classes of asthma medications. Assessment of bronchoprotection using methacholine dose-response curves may be useful during clinical development of respiratory medications when performing superiority, equivalence, or non-inferiority trials.Trial registrationclinicaltrials.gov (NCT02953041). Retrospectively registered on October 24th 2016.

Different cutoff values of methacholine bronchial provocation test depending on age in children with asthma.

Bronchial hyperresponsiveness (BHR) is a fundamental pathophysiological characteristic of asthma. Although several factors such as airway caliber can affect BHR, no study has established age-dependent cutoff values of BHR to methacholine for the diagnosis of asthma in children. We investigated the cutoff values of the methacholine challenge test (MCT) in the diagnosis of asthma according to age. A total of 2383 individuals aged from 6 to 15 years old were included in this study. MCTs using the five-breath technique were performed in 350 children with suspected asthma based on symptoms by pediatric allergists and in 2033 healthy children from a general population-based cohort. We determined the provocative concentration of methacholine producing a 20% decrease in forced expiratory volume in 1 second from baseline (PC20). A modified Korean version of the International Study of Asthma and Allergies in Childhood questionnaire was used to distinguish asthmatics and healthy subjects. Receiver-operator characteristic curve analysis was used to assess the cutoff value of PC20 for the diagnosis of asthma. Cutoff values of methacholine PC20, which provided the best combination of diagnostic sensitivity and specificity, showed an increasing pattern with age: 5.8, 9.1, 11.8, 12.6, 14.9, 21.7, 23.3, 21.1, 21.1, and 24.6 mg/mL at ages 6, 7, 8, 9, 10, 11, 12, 13, 14, and 15 years, respectively. The application of different cutoff values of methacholine PC20 depending on age might be a practical modification for the diagnosis of asthma in children and adolescents with asthmatic symptoms.

Increased sputum levels of thymus and activation-regulated chemokine in children with asthma not eosinophilic bronchitis

BackgroundThymus and activation-regulated chemokine (TARC), a member of the CC chemokine family, plays a crucial role in Th2-specific inflammation. We aimed to determine the concentration of sputum TARC in children with asthma and eosinophilic bronchitis (EB) and its relation with eosinophilic inflammation, pulmonary function, and bronchial hyper-responsiveness. MethodsIn total, 90 children with asthma, 38 with EB, and 45 control subjects were enrolled. TARC levels were measured in sputum supernatants using an ELISA. We performed pulmonary function tests and measured exhaled fractional nitric oxide, eosinophil counts in blood, and sputum and serum levels of total IgE in all children. ResultsSputum TARC levels were significantly higher in children with asthma than in either children with EB (p=0.004) or the control subjects (p=0.014). Among patients with asthma, sputum TARC concentration was higher in children with sputum eosinophilia than in those without sputum eosinophilia (p=0.035). Sputum TARC levels positively correlated with eosinophil counts in sputum, serum total IgE levels, exhaled fractional nitric, and the bronchodilator response. Negative significant correlations were found between sputum TARC and FEV1/FVC (the ratio of forced expiratory volume in one second and forced expiratory vital capacity) or PC20 (the provocative concentration of methacholine causing a 20% decrease in the FEV1). ConclusionElevated TARC levels in sputum were detected in children with asthma but not in children with EB. Sputum TARC could be a supportive marker for discrimination of asthma from EB in children showing characteristics of eosinophilic airway inflammation.

P115 Smoking and airway hyperactivity in airways hyper-responsive (AHR) to methacholine

Provocative concentration of methacholine that reduces FEV1 by 20% (PC20) is a measure of AHR used to diagnose asthma. Our study is aimed at exploring relationship between smoking and PC20 in individuals suspected to have asthma, whose airways are hyper-responsive to methacholine.

Duration of bronchoprotection of the long-acting muscarinic antagonists tiotropium & glycopyrronium against methacholine-induced bronchoconstriction in mild asthmatics

The duration of bronchoprotection against methacholine-induced bronchoconstriction by long-acting muscarinic antagonists (LAMA’s) in asthmatics and whether these drugs differ in their pharmacodynamic properties remain to be determined. The most recent published guidelines for methacholine challenge testing (MCT) suggest that LAMA’s should be abstained from for 48 h prior to testing, perhaps one week in the case of tiotropium.The objectives were to determine and compare the duration of protection of a single dose of two different LAMA’s, tiotropium and glycopyrronium, against methacholine-induced bronchoconstriction.Thirteen mild-to-moderate asthmatics [with a forced expiratory volume in 1 s (FEV1) > 65% of predicted and a baseline methacholine provocation concentration causing a 20% reduction in FEV1 (PC20) ≤ 8 mg/mL] completed this double-blind, double-dummy, crossover study. Methacholine challenges were performed before treatment (5 μg tiotropium or 50 μg glycopyrronium) and at 1, 24, 48, 72, 96 and 168 h post-treatment. The minimum duration between treatment administration was 11 days.Both drugs provided significant bronchoprotection, each producing greater than a 16-fold increase in mean PC20 by 1 h. Tiotropium still provided statistically significant protection at 7 days (p = 0.0282) while glycopyrronium provided bronchoprotection until day 7 (p = 0.0590). Tiotropium provided statistically superior bronchoprotection at 24 and 72 h compared to glycopyrronium.To minimize the occurrence of false negatives, MCT guidelines should be updated to recommend a minimum one-week abstinence period from all LAMA’s. MCT was also able to statistically differentiate between tiotropium and glycopyrronium with respect to the degree and duration of bronchoprotection provided by each.Clinical trial registration number: NCT02622243.