Exercise-induced wheeze: Fraction of exhaled nitric oxide-directed management

Breathing Easy During Training. Strategies for Managing Exercise-Induced Bronchoconstriction

Exercise-induced asthma (EIA) and exercise-induced bronchoconstriction (EIB) are closely related conditions that can make it challenging to differentiate between them. These conditions necessitate that asthmatic patients adhere to established asthma guidelines for baseline treatment. Short-acting beta-agonists are emphasized as the primary treatment for managing symptoms. The management of EIA and EIB in children is particularly complex due to their high levels of spontaneous physical activity. Patients must identify and avoid environmental triggers that may exacerbate their symptoms whenever possible. For effective management, physicians should regularly assess treatment efficacy through the remission of symptoms. However, athletes may require more specialized and serial testing to tailor their treatment plans effectively and ensure optimal performance. This article encapsulates the critical points concerning managing exercise-induced respiratory issues in asthmatic individuals, highlighting the need for careful and tailored approaches for different patient groups.

High fractional exhaled nitric oxide levels in asthma patients: Does size matter?

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is a biomarker for eosinophilic inflammation used for diagnosis and monitoring of asthma. High FeNO indicates significant airway eosinophilia and steroid-responsive airway inflammation. Some children with asthma have extremely high FeNO levels, but whether these levels represent a different asthma phenotype compared with those with mildly elevated FeNO is unclear. The objective of this study is to investigate whether the extent of high FeNO levels correlates with clinical phenotype, asthma control, comorbidity, and pulmonary function test (PFT) findings in children with asthma.

METHODS

Anthropometric data, daytime and nighttime symptoms, controller treatment, comorbidity, and PFT findings were retrieved from the Pediatric Pulmonology Unit database (2014-2020) and correlated with FeNO levels in pediatric asthma patients with high FeNO levels.

RESULTS

Two-hundred children and adolescents with high FeNO levels (range 36-227 ppb) were included. Within this range, higher FeNO levels positively correlated with increased daytime and nighttime symptoms (p = .013 and p = .01, respectively) and poorly controlled asthma (p = .034). A FeNO level of ≥80 ppb was the cutoff for significantly more severe daytime and nighttime symptoms and very poorly controlled asthma compared with levels <80 ppb (p = .004, p = .005, and p = .036, respectively). No correlation was found between FeNO and controller treatment, comorbidity, and PFT performance.

CONCLUSION

In pediatric asthma patients, high FeNO levels correlate with increased symptom severity and poor asthma control. A FeNO level of ≥80 ppb may serve as an objective indicator for severe asthma.

Identification of airway mucosal type 2 inflammation by using clinical biomarkers in asthmatic patients

BACKGROUND

The Airways Disease Endotyping for Personalized Therapeutics (ADEPT) study profiled patients with mild, moderate, and severe asthma and nonatopic healthy control subjects.

OBJECTIVE

We explored this data set to define type 2 inflammation based on airway mucosal IL-13-driven gene expression and how this related to clinically accessible biomarkers.

METHODS

IL-13-driven gene expression was evaluated in several human cell lines. We then defined type 2 status in 25 healthy subjects, 28 patients with mild asthma, 29 patients with moderate asthma, and 26 patients with severe asthma based on airway mucosal expression of (1) CCL26 (the most differentially expressed gene), (2) periostin, or (3) a multigene IL-13 in vitro signature (IVS). Clinically accessible biomarkers included fraction of exhaled nitric oxide (Feno) values, blood eosinophil (bEOS) counts, serum CCL26 expression, and serum CCL17 expression.

RESULTS

Expression of airway mucosal CCL26, periostin, and IL-13-IVS all facilitated segregation of subjects into type 2-high and type 2-low asthmatic groups, but in the ADEPT study population CCL26 expression was optimal. All subjects with high airway mucosal CCL26 expression and moderate-to-severe asthma had Feno values (≥35 ppb) and/or high bEOS counts (≥300 cells/mm³) compared with a minority (36%) of subjects with low airway mucosal CCL26 expression. A combination of Feno values, bEOS counts, and serum CCL17 and CCL26 expression had 100% positive predictive value and 87% negative predictive value for airway mucosal CCL26-high status. Clinical variables did not differ between subjects with type 2-high and type 2-low status. Eosinophilic inflammation was associated with but not limited to airway mucosal type 2 gene expression.

CONCLUSION

A panel of clinical biomarkers accurately classified type 2 status based on airway mucosal CCL26, periostin, or IL-13-IVS gene expression. Use of Feno values, bEOS counts, and serum marker levels (eg, CCL26 and CCL17) in combination might allow patient selection for novel type 2 therapeutics.

Airway hyperresponsiveness to mannitol and methacholine and exhaled nitric oxide in children with asthma

OBJECTIVE

Asthma is characterized by airway hyperresponsiveness (AHR), inflammation, and obstruction. AHR to stimuli that indirectly cause bronchial smooth muscle (BSM) contractions via release of endogenous mediators is thought to better reflect airway inflammation than AHR to stimuli that act directly on BSM. Fractional exhaled nitric oxide (FeNO) is a useful parameter for noninvasive clinical airway inflammation assessments. Accordingly, this study aimed to examine the relationships of mannitol and methacholine challenge test outcomes with FeNO and the influence of inhaled corticosteroid treatment in children with asthma.

METHODS

One hundred thirty-four asthmatic children (89 males; ages: 5-17 years, median: 9 years) underwent spirometry, FeNO measurement, serum total/specific IgE testing, and blood eosinophil count. All subjects were challenged with mannitol dry powder (MDP; AridolH, Pharmaxis, Australia) and methacholine at 7-day intervals. Data of steroid-treated and steroid-naïve children were compared.

RESULTS

Positive responses to MDP and methacholine challenge tests were observed in 74.6% and 67.2% of total subject group, respectively, and 72 children had positive response to both challenge tests. The median FeNO level, response-dose ratio (RDR) of PC₂₀ methacholine, and RDR of PD₁₅ MDP were significantly higher in the steroid-treated group than in the steroid-naïve group (p < 0.001, 0.226, and 0.004, respectively). FeNO levels associated significantly with PD₁₅ MDP and RDR PD₁₅ MDP in total subject populations (p = 0.016 and 0.003, respectively); however, a significant correlation between FeNO and RDR PD₁₅ MDP was observed only in the steroid-naïve group.

CONCLUSIONS

Compared with AHR to methacholine, AHR to MDP more closely reflected the level of FeNO in steroid-naïve asthmatic children.

Leukotriene inhibitors for bronchiolitis in infants and young children

BACKGROUND

Bronchiolitis is an acute inflammatory illness of the bronchioles common among infants and young children. It is often caused by the respiratory syncytial virus (RSV). Management of bronchiolitis varies between clinicians, reflecting the lack of evidence for a specific treatment approach. The leukotriene pathway has been reported to be involved in the pathogenesis of bronchiolitis. Leukotriene inhibitors such as montelukast have been used in infants and young children with bronchiolitis. However, the results from limited randomised controlled trials (RCTs) are controversial and necessitate a thorough evaluation of their efficacy for bronchiolitis in infants and young children.

OBJECTIVES

To assess the efficacy and safety of leukotriene inhibitors for bronchiolitis in infants and young children.

SEARCH METHODS

We searched CENTRAL (2014, Issue 5), MEDLINE (1946 to April week 4, 2014), EMBASE (1974 to May 2014), CINAHL (1981 to May 2014), LILACS (1982 to May 2014), Web of Science (1985 to May 2014), WHO ICTRP and ClinicalTrials.gov (6 May 2014).

SELECTION CRITERIA

RCTs comparing leukotriene inhibitors versus placebo or another intervention in infants and young children under two years of age diagnosed with bronchiolitis. Our primary outcomes were length of hospital stay and all-cause mortality. Secondary outcomes included clinical severity score, percentage of symptom-free days, percentage of children requiring ventilation, oxygen saturation, recurrent wheezing, respiratory rate and clinical adverse effects.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane Collaboration methodological practices. Two authors independently assessed trial eligibility and extracted data, such as general information, participant characteristics, interventions and outcomes. We assessed risk of bias and graded the quality of the evidence. We used Review Manager software to pool results and chose random-effects models for meta-analysis.

MAIN RESULTS

We included five studies with a total of 1296 participants under two years of age hospitalised with bronchiolitis. Two studies with low risk of bias compared 4 mg montelukast (a leukotriene inhibitor) daily use from admission until discharge with a matching placebo. Both selected length of hospital stay as a primary outcome and clinical severity score as a secondary outcome. However, the effects of leukotriene inhibitors on length of hospital stay and clinical severity score were uncertain due to considerable heterogeneity between the study results and wide confidence intervals around the estimated effects (hospital stay: mean difference (MD) -0.95 days, 95% confidence interval (CI) -3.08 to 1.19, P value = 0.38, low quality evidence; clinical severity score on day two: MD -0.57, 95% CI -2.37 to 1.23, P value = 0.53, low quality evidence; clinical severity score on day three: MD 0.17, 95% CI -1.93 to 2.28, P value = 0.87, low quality evidence). The other three studies compared montelukast for several weeks for preventing post-bronchiolitis symptoms with placebo. We assessed one study as low risk of bias, whereas we assessed the other two studies as having a high risk of attrition bias. Due to the significant clinical heterogeneity in severity of disease, duration of treatment, outcome measurements and timing of assessment, we did not pool the results. Individual analyses of these studies did not show significant differences between the leukotriene inhibitors group and the control group in symptom-free days and incidence of recurrent wheezing. One study of 952 children reported two deaths in the leukotriene inhibitors group: neither was determined to be drug-related. No data were available on the percentage of children requiring ventilation, oxygen saturation and respiratory rate. Finally, three studies reported adverse events including diarrhoea, wheezing shortly after administration and rash. No differences were reported between the study groups.

AUTHORS' CONCLUSIONS

The current evidence does not allow definitive conclusions to be made about the effects of leukotriene inhibitors on length of hospital stay and clinical severity score in infants and young children with bronchiolitis. The quality of the evidence was low due to inconsistency (unexplained high levels of statistical heterogeneity) and imprecision arising from small sample sizes and wide confidence intervals, which did not rule out a null effect or harm. Data on symptom-free days and incidence of recurrent wheezing were from single studies only. Further large studies are required. We identified one registered ongoing study, which may make a contribution in the updates of this review.

Exhaled Nitric Oxide and Airway Hyperresponsiveness to Adenosine 5'-monophosphate and Methacholine in Children with Asthma

BACKGROUND

There is increasing interest in the role of indirect bronchial challenges because clinical studies have shown that indirect airway hyperresponsiveness (AHR) reflects underlying airway inflammation better than direct AHR. Fractional exhaled nitric oxide (FeNO) appears to be a useful clinical tool for assessing airway inflammation noninvasively. We examined whether FeNO is more closely related to AHR to indirect stimuli than AHR to direct stimuli in children with mild to moderate asthma.

METHODS

Fifty-nine asthmatic children aged 6-16 years without rhinitis, underwent spirometry, FeNO measurement and blood tests for serum total IgE, blood eosinophil count and serum eosinophil cationic protein (ECP). All subjects underwent methacholine and adenosine 5-monophosphate (AMP) challenge tests at intervals of 3 days.

RESULTS

In a univariate linear regression analysis, FeNO was significantly associated with both PC20 AMP (R(2) = 0.341, p < 0.001) and PC20 methacholine (R(2) = 0.188, p = 0.001). After adjustment for age, sex, serum total IgE and blood eosinophil count, the association between FeNO and PC20 AMP (β = -1.98, p = 0.001) was more robust than that between FeNO and PC20 methacholine (β = -0.87, p = 0.081). The significant correlation between FeNO and PC20 AMP was observed in the steroid-naïve group (β = -2.48, p = 0.001), but not in the steroid-treated group (β = 0.88, p = 0.463).

CONCLUSIONS

FeNO levels were more closely associated with PC20 AMP than with PC20 methacholine. This relationship could only be seen in the steroid-naïve subjects. These results suggest that FeNO levels in children with asthma may be more closely related to indirect AHR than to direct AHR.

FeNO as a predictor of asthma control improvement after starting inhaled steroid treatment

INTRODUCTION

The fraction of NO in exhaled air (FeNO) is a marker of inflammation in asthma. The aim of the present study was to assess, in a real-world setting, whether only high (⩾50 ppb) FeNO levels predict improvement in asthma control when being treated with inhaled corticosteroids (ICS), as suggested by current guidelines on the clinical use of FeNO.

METHODS

FeNO and asthma control were assessed in a retrospective observational study in 153 non-smoking, steroid-naïve, adult subjects with asthma with a mean age of 40 years both before and after 6 weeks (median follow-up time) of treatment with 500 μg beclomethasone (median).

RESULTS

Having at the initial visit intermediate FeNO (⩾25 and <50 ppb) and high FeNO (⩾50 ppb), compared to normal FeNO (<25 ppb), were associated with a larger proportion of subjects achieving an improvement of Asthma Control Questionnaire (ACQ) score with ⩾1 (78% and 67% vs 43%, p<0.05) or both ⩾1 improvement and asthma control at follow-up (31% and 37% vs 4%, p<0.05). These associations were consistent in multiple logistic regression models after adjustments for confounders.

CONCLUSIONS

It is not only high but also intermediate FeNO levels that are associated with a significant improvement in asthma control after starting ICS treatment. This challenges current clinical guidelines stating that only high FeNO levels predict response to ICS treatment.

Addition to inhaled corticosteroids of long-acting beta2-agonists versus anti-leukotrienes for chronic asthma

BACKGROUND

Asthma patients who continue to experience symptoms despite taking regular inhaled corticosteroids (ICS) represent a management challenge. Long-acting beta2-agonists (LABA) and anti-leukotrienes (LTRA) are two treatment options that could be considered as add-on therapy to ICS.

OBJECTIVES

To compare the safety and efficacy of adding LABA versus LTRA to the treatment regimen for children and adults with asthma who remain symptomatic in spite of regular treatment with ICS. We specifically wished to examine the relative impact of the two agents on asthma exacerbations, lung function, symptoms, quality of life, adverse health events and withdrawals.

SEARCH METHODS

We searched the Cochrane Airways Group Specialised Register until December 2012. We consulted reference lists of all included studies and contacted pharmaceutical manufacturers to ask about other published or unpublished studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) conducted in adults or children with recurrent asthma that was treated with ICS along with a fixed dose of a LABA or an LTRA for a minimum of four weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the risk of bias of included studies and extracted data. We sought unpublished data and further details of study design when necessary.

MAIN RESULTS

We included 18 RCTs (7208 participants), of which 16 recruited adults and adolescents (6872) and two recruited children six to 17 years of age (336) with asthma and significant reversibility to bronchodilator at baseline. Fourteen (79%) trials were of high methodological quality.The risk of exacerbations requiring systemic corticosteroids (primary outcome of the review) was significantly lower with the combination of LABA + ICS compared with LTRA + ICS-from 13% to 11% (eight studies, 5923 adults and 334 children; risk ratio (RR) 0.87, 95% confidence interval (CI) 0.76 to 0.99; high-quality evidence). The number needed to treat for an additional beneficial outcome (NNTB) with LABA compared with LTRA to prevent one additional exacerbation over four to 102 weeks was 62 (95% CI 34 to 794). The choice of LTRA, the dose of ICS and the participants' age group did not significantly influence the magnitude of effect. Although results were inconclusive, the effect appeared stronger in trials that used a single device rather than two devices to administer ICS and LABA and in trials of less than 12 weeks' duration.The addition of LABA to ICS was associated with a statistically greater improvement from baseline in lung function, as well as in symptoms, rescue medication use and quality of life, although the latter effects were modest. LTRA was superior in the prevention of exercise-induced bronchospasm. More participants were satisfied with the combination of LABA + ICS than LTRA + ICS (three studies, 1625 adults; RR 1.12, 95% CI 1.04 to 1.20; moderate-quality evidence). The overall risk of withdrawal was significantly lower with LABA + ICS than with LTRA + ICS (13 studies, 6652 adults and 308 children; RR 0.84, 95% CI 0.74 to 0.96; moderate-quality evidence). Although the risk of overall adverse events was equivalent between the two groups, the risk of serious adverse events (SAE) approached statistical significance in disfavour of LABA compared with LTRA (nine studies, 5658 adults and 630 children; RR 1.33, 95% CI 0.99 to 1.79; P value 0.06; moderate-quality evidence), with no apparent impact of participants' age group.The following adverse events were reported, but no significant differences were demonstrated between groups: headache (11 studies, N = 6538); cardiovascular events (five studies, N = 5163), osteopenia and osteoporosis (two studies, N = 2963), adverse events (10 studies, N = 5977 adults and 300 children). A significant difference in the risk of oral moniliasis was noted, but this represents a low occurrence rate.

AUTHORS' CONCLUSIONS

In adults with asthma that is inadequately controlled by predominantly low-dose ICS with significant bronchodilator reversibility, the addition of LABA to ICS is modestly superior to the addition of LTRA in reducing oral corticosteroid-treated exacerbations, with an absolute reduction of two percentage points. Differences favouring LABA over LTRA as adjunct therapy were observed in lung function and, to a lesser extend, in rescue medication use, symptoms and quality of life. The lower overall withdrawal rate and the higher proportion of participants satisfied with their therapy indirectly favour the combination of LABA + ICS over LTRA + ICS. Evidence showed a slightly increased risk of SAE with LABA compared with LTRA, with an absolute increase of one percentage point. Our findings modestly support the use of a single inhaler for the delivery of both LABA and low- or medium-dose ICS. Because of the paucity of paediatric trials, we are unable to draw firm conclusions about the best adjunct therapy in children.

Assessment of EIB: What you need to know to optimize test results

Respiratory symptoms and asthma control questionnaires are poor predictors of the presence or severity of exercise-induced bronchoconstriction (EIB), and objective measurement is recommended. To optimize the chance of a positive test result, there are several factors to consider when exercising patients for EIB, including the ventilation achieved and sustained during exercise, water content of the inspired air, and the natural variability of the response. The high rate of negative exercise test results has led to the development of surrogates to identify EIB in laboratory or office settings, including eucapnic voluntary hyperpnea of dry air and inhalation of hyperosmolar aerosols.

Exercise-induced bronchoconstriction in school-age children born extremely preterm

BACKGROUND

School children born preterm often show airway hyperresponsiveness to methacholine or histamine. Less attention has been paid to their airway response to exercise, an important point because of the role of exercise in the child's daily life. The aim of this study was to describe the characteristics of, and potential determinants to, the airway response to exercise in children born extremely preterm.

METHODS

Forty-two nonasthmatic nonatopic children born before 32 wk gestation were compared with 27 healthy nonasthmatic nonatopic term children at age 7. Spirometry and respiratory impedance were measured at baseline and repeated after a single-step 6-min treadmill exercise in a climate-controlled room.

RESULTS

The preterm group showed significant broncho-constriction induced by exercise. Prematurity, but not low baseline lung function, neonatal oxygen supplementation, mechanical ventilation, chronic lung disease, or maternal smoking, was a determinant of exercise-induced bronchoconstriction.

CONCLUSION

Children born extremely preterm present significant exercise-induced airway obstruction at age 7. The response has different characteristics from that occurring in asthmatics and is likely to express airway noneosinophilic inflammation.

Airway hyperresponsiveness in asthma: mechanisms, clinical significance, and treatment

Airway hyperresponsiveness (AHR) and airway inflammation are key pathophysiological features of asthma. Bronchial provocation tests (BPTs) are objective tests for AHR that are clinically useful to aid in the diagnosis of asthma in both adults and children. BPTs can be either “direct” or “indirect,” referring to the mechanism by which a stimulus mediates bronchoconstriction. Direct BPTs refer to the administration of pharmacological agonist (e.g., methacholine or histamine) that act on specific receptors on the airway smooth muscle. Airway inflammation and/or airway remodeling may be key determinants of the response to direct stimuli. Indirect BPTs are those in which the stimulus causes the release of mediators of bronchoconstriction from inflammatory cells (e.g., exercise, allergen, mannitol). Airway sensitivity to indirect stimuli is dependent upon the presence of inflammation (e.g., mast cells, eosinophils), which responds to treatment with inhaled corticosteroids (ICS). Thus, there is a stronger relationship between indices of steroid-sensitive inflammation (e.g., sputum eosinophils, fraction of exhaled nitric oxide) and airway sensitivity to indirect compared to direct stimuli. Regular treatment with ICS does not result in the complete inhibition of responsiveness to direct stimuli. AHR to indirect stimuli identifies individuals that are highly likely to have a clinical improvement with ICS therapy in association with an inhibition of airway sensitivity following weeks to months of treatment with ICS. To comprehend the clinical utility of direct or indirect stimuli in either diagnosis of asthma or monitoring of therapeutic intervention requires an understanding of the underlying pathophysiology of AHR and mechanisms of action of both stimuli.

Mast cell number, phenotype, and function in human pulmonary arterial hypertension

A proliferation of mast cells around the small pulmonary blood vessels and the alveolar septae has been noted in models of pulmonary hypertension, and in plexiform lesions of pulmonary arterial hypertension (PAH) in patients. Here, we hypothesize that total mast cell numbers and activation are increased in PAH and that they contribute to vascular remodeling through cellular and soluble proangiogenic effectors. To test this, blood and urine were collected from patients with PAH (N=44), asthma (N=18) and healthy controls (N=29) to quantitate biomarkers of total body mast cell numbers and activation (total and mature tryptase, N-methyl histamine, leukotriene LTE(4) and prostaglandin PGD-M). Serum total tryptase was higher in PAH than that in controls suggesting greater numbers of mast cells, but indicators of mast cell activation (mature tryptase, LTE(4) and PGD-M) were similar among PAH, asthma, and controls. Immunohistochemistry of lung tissues identified mast cells as primarily perivascular and connective tissue chymase(+) type in PAH, rather than mucosal phenotype. Intervention with mast cell inhibitors cromolyn and fexofenadine was performed in 9 patients for 12 weeks to identify the influence of mast cell products on the pathologic proangiogenic environment. Treatment decreased total tryptase and LTE-4 levels over time of treatment. This occurred in parallel to a drop in vascular endothelial growth factor (VEGF) and circulating proangiogenic CD34+CD133+ progenitor cells, which suggests that mast cells may promote vascular remodeling and dysfunction. In support of this, levels of exhaled nitric oxide, a vasodilator that is generally low in PAH, increased at the end of the 12-week mast cell blockade and antihistamine. These results suggest that mast cells might contribute to the pulmonary vascular pathologic processes underlying PAH. More studies are needed to confirm their potential contribution to the disease.

Anti-leukotriene agents compared to inhaled corticosteroids in the management of recurrent and/or chronic asthma in adults and children

BACKGROUND

Anti-leukotrienes (5-lipoxygenase inhibitors and leukotriene receptors antagonists) serve as alternative monotherapy to inhaled corticosteroids (ICS) in the management of recurrent and/or chronic asthma in adults and children.

OBJECTIVES

To determine the safety and efficacy of anti-leukotrienes compared to inhaled corticosteroids as monotherapy in adults and children with asthma and to provide better insight into the influence of patient and treatment characteristics on the magnitude of effects.

SEARCH METHODS

We searched MEDLINE (1966 to Dec 2010), EMBASE (1980 to Dec 2010), CINAHL (1982 to Dec 2010), the Cochrane Airways Group trials register, and the Cochrane Central Register of Controlled Trials (Dec 2010), abstract books, and reference lists of review articles and trials. We contacted colleagues and the international headquarters of anti-leukotrienes producers.

SELECTION CRITERIA

We included randomised trials that compared anti-leukotrienes with inhaled corticosteroids as monotherapy for a minimum period of four weeks in patients with asthma aged two years and older.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the methodological quality of trials and extracted data. The primary outcome was the number of patients with at least one exacerbation requiring systemic corticosteroids. Secondary outcomes included patients with at least one exacerbation requiring hospital admission, lung function tests, indices of chronic asthma control, adverse effects, withdrawal rates and biological inflammatory markers.

MAIN RESULTS

Sixty-five trials met the inclusion criteria for this review. Fifty-six trials (19 paediatric trials) contributed data (representing total of 10,005 adults and 3,333 children); 21 trials were of high methodological quality; 44 were published in full-text. All trials pertained to patients with mild or moderate persistent asthma. Trial durations varied from four to 52 weeks. The median dose of inhaled corticosteroids was quite homogeneous at 200 µg/day of microfine hydrofluoroalkane-propelled beclomethasone or equivalent (HFA-BDP eq). Patients treated with anti-leukotrienes were more likely to suffer an exacerbation requiring systemic corticosteroids (N = 6077 participants; risk ratio (RR) 1.51, 95% confidence interval (CI) 1.17, 1.96). For every 28 (95% CI 15 to 82) patients treated with anti-leukotrienes instead of inhaled corticosteroids, there was one additional patient with an exacerbation requiring rescue systemic corticosteroids. The magnitude of effect was significantly greater in patients with moderate compared with those with mild airway obstruction (RR 2.03, 95% CI 1.41, 2.91 versus RR 1.25, 95% CI 0.97, 1.61), but was not significantly influenced by age group (children representing 23% of the weight versus adults), anti-leukotriene used, duration of intervention, methodological quality, and funding source. Significant group differences favouring inhaled corticosteroids were noted in most secondary outcomes including patients with at least one exacerbation requiring hospital admission (N = 2715 participants; RR 3.33; 95% CI 1.02 to 10.94), the change from baseline FEV(1) (N = 7128 participants; mean group difference (MD) 110 mL, 95% CI 140 to 80) as well as other lung function parameters, asthma symptoms, nocturnal awakenings, rescue medication use, symptom-free days, the quality of life, parents' and physicians' satisfaction. Anti-leukotriene therapy was associated with increased risk of withdrawals due to poor asthma control (N = 7669 participants; RR 2.56; 95% CI 2.01 to 3.27). For every thirty one (95% CI 22 to 47) patients treated with anti-leukotrienes instead of inhaled corticosteroids, there was one additional withdrawal due to poor control. Risk of side effects was not significantly different between both groups.

AUTHORS' CONCLUSIONS

As monotherapy, inhaled corticosteroids display superior efficacy to anti-leukotrienes in adults and children with persistent asthma; the superiority is particularly marked in patients with moderate airway obstruction. On the basis of efficacy, the results support the current guidelines' recommendation that inhaled corticosteroids remain the preferred monotherapy. 

Diagnostic exercise challenge testing

This article reviews the diagnostic challenge methods-both exercise and surrogate-for diagnosis of exercise-induced bronchoconstriction (EIB) and EIB with known asthma. Indirect challenges that release the entire repertoire of mediators representative of EIB and asthma are more specific for diagnosis and are recommended over direct challenges such as methacholine challenge, which are sensitive but nonspecific. Self-reported history and empiric therapeutic trials are not adequate for diagnosis of EIB with or without known asthma. Objective pulmonary function documentation with bronchodilator reversibility or exercise or surrogate challenge are optimal for diagnosis of EIB or EIB with known asthma. Such objective pulmonary function documentation is optimal for the proper management and healthy lifestyle of the exercising athlete or individual.

Bronchial provocation testing: the future

PURPOSE OF REVIEW

Performing a bronchial provocation test (BPT) using a direct or indirect stimulus to identify bronchial hyper-responsiveness (BHR) reduces the possibility of over and under-diagnosis of asthma based on history and symptoms. This review discusses some long-held beliefs of BPTs to include or exclude a diagnosis of asthma or exercise-induced bronchoconstriction (EIB).

RECENT FINDINGS

A high frequency of negative methacholine tests has been reported in 240 patients given a diagnosis of asthma at the end of the study, many of whom had documented EIB. This suggests that a negative methacholine test should not be relied upon to rule out asthma. Further, a positive methacholine test alone should be interpreted with caution as it may reflect airway injury rather than asthma or EIB. Mannitol, an indirect stimulus, identified a similar prevalence of BHR to methacholine and identified more patients than a single exercise test in three studies. However, neither mannitol nor methacholine identified all patients with EIB. Mannitol has a higher specificity for a physician diagnosis of asthma than methacholine.

SUMMARY

It is likely that both a direct test and an indirect test result may be required in some patients in order to confirm or exclude a diagnosis of asthma with certainty.