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

BACKGROUND: Most 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. METHODS: Our 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. RESULTS: The 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%. CONCLUSIONS: Our 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.

Single-step direct drug provocation testing is safe for delabelling selected non-low-risk penicillin allergy labels.

BACKGROUND: Penicillin allergy labels are prevalent, and removal of incorrect labels improves patient outcomes and health economics. Labels may be classified as "low-risk" or "non-low-risk," of which the symptoms of the latter chiefly suggest immunoglobulin E-mediated etiology. Traditionally, "non-low-risk" allergy labels are evaluated by penicillin skin testing followed by graded multistep penicillin drug provocation testing (DPT). OBJECTIVE: To evaluate the safety of assessing "non-low-risk" labels with single-step direct DPT. METHODS: We consecutively enrolled inpatients and outpatients of a teaching hospital in Sydney, Australia, with penicillin allergy labels requiring penicillin for first-line treatment. Patients were classified as "low-risk" or "non-low-risk" based on the allergy labels. All patients proceeded directly to amoxicillin DPT, unless there was a history of anaphylaxis within 10 years of assessment to a beta-lactam (except for cefazolin) or Gell and Coombs type 2, type 3, or severe type 4 reaction. This was followed by a course of amoxicillin. RESULTS: A total of 149 patients (41 inpatients, 108 outpatients) were enrolled. No patient was excluded from the study. No patient experienced life-threatening reactions to the protocol. There were 85 patients who reported "non-low-risk" allergy labels. One patient developed generalized pruritus and rash that resolved with standard-dose antihistamines, 2 developed delayed benign maculopapular exanthem, and 3 experienced diarrhea during the course of amoxicillin. CONCLUSION: In our cohort, direct single-step DPT was safe, with only 6 patients with "non-low-risk" allergy experiencing benign reactions. We hope that further studies can be performed into single-step direct DPT to evaluate "non-low-risk" penicillin allergy labels. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: LNR/16/HAWKE/452.

The use of a direct bronchial challenge test in primary care to diagnose asthma.

Many asthmatics in primary care have mild symptoms and lack airflow obstruction. If variable expiratory airflow limitation cannot be determined by spirometry or peak expiratory flow, despite a history of respiratory symptoms, a positive bronchial challenge test (BCT) can confirm the diagnosis of asthma. However, BCT is traditionally performed in secondary care. In this observational real-life study, we retrospectively analyze 5-year data of a primary care diagnostic center carrying out BCT by histamine provocation. In total, 998 primary care patients aged ≥16 years underwent BCT, without any adverse events reported. To explore diagnostic accuracy, we examine 584 patients with a high pretest probability of asthma. Fifty-seven percent of these patients have a positive BCT result and can be accurately diagnosed with asthma. Our real-life data show BCT is safe and feasible in a suitably equipped primary care diagnostic center. Furthermore, it could potentially reduce diagnostic referrals to secondary care.

In Vivo Allergen-Activated Eosinophils Promote Collagen I and Fibronectin Gene Expression in Airway Smooth Muscle Cells via TGF-ß1 Signaling Pathway in Asthma.

Eosinophils infiltration and releasing TGF-ß1 in the airways has been implicated in the pathogenesis of asthma, especially during acute episodes provoked by an allergen. TGF-ß1 is a major mediator involved in pro-inflammatory responses and fibrotic tissue remodeling in asthma. We aimed to evaluate the effect of in vivo allergen-activated eosinophils on the expression of COL1A1 and FN in ASM cells in asthma. A total of 12 allergic asthma patients and 11 healthy subjects were examined. All study subjects underwent bronchial challenge with D. pteronyssinus allergen. Eosinophils from peripheral blood were isolated before and 24 h after the bronchial allergen challenge using high-density centrifugation and magnetic separation. Individual co-cultures of blood eosinophils and immortalized human ASM cells were prepared. The TGF-ß1 concentration in culture supernatants was analyzed using ELISA. Gene expression was analyzed using qRT-PCR. Eosinophils integrins were suppressed with linear RGDS peptide before co-culture with ASM cells. Results: The expression of TGF-ß1 in asthmatic eosinophils significantly increased over non-activated asthmatic eosinophils after allergen challenge, p < 0.001. The TGF-ß1 concentration in culture supernatants was significantly higher in samples with allergen-activated asthmatic eosinophils compared to baseline, p < 0.05. The effect of allergen-activated asthmatic eosinophils on the expression of TGF-ß1, COL1A1, and FN in ASM cells was more significant compared to non-activated eosinophils, p < 0.05, however, no difference was found on WNT-5A expression. The incubation of allergen-activated asthmatic eosinophils with RGDS peptide was more effective compared to non-activated eosinophils as the gene expression in ASM cells was downregulated equally to the same level as healthy eosinophils.

Bronchodilator test in extreme old age: Adverse effects of short-acting beta-2 adrenergic agonists with clinical repercussion and bronchodilator response.

OBJECTIVE: To evaluate chronological age as a limiting factor to perform the bronchodilator test, determine significant adverse effects of short-acting beta 2 agonists with clinical repercussions, and assess bronchodilator response in extreme-old-age patients who undergo the spirometry test. METHODS: This is a cross-sectional and retrospective study. The sample was extracted from the database (spirometer and respiratory questionnaire) of a pulmonary function service. Patients over 90 years old were included in the research, and we evaluated their bronchodilator response and its significant adverse effects that may have clinical repercussions related to the bronchodilator. RESULTS: A sample of 25 patients aged 92.12 ± 2.22 years (95% CI, 91.20 - 93.04), with a minimum age of 90 years and a maximum of 97 years and a predominance of females with 72% (18/25). The bronchodilator test was performed in 84% (21/25) of the patients. The bronchodilator response was evaluated in 19 of the 21 patients (90.47%) who underwent the bronchodilator test. Two tests did not meet the criteria of acceptability and reproducibility. No clinical adverse effects were observed with the bronchodilator medication (salbutamol) during or after the exam. CONCLUSIONS: Chronological age is not a limiting factor for the bronchodilator test, short-acting beta-2 agonists did not present adverse effects with significant clinical repercussion and were useful in the diagnosis and therapeutic guidance of extreme-old-age patients.

Bronchodilator test in extreme old age: Adverse effects of short-acting beta-2 adrenergic agonists with clinical repercussion and bronchodilator response

SUMMARY OBJECTIVE: To evaluate chronological age as a limiting factor to perform the bronchodilator test, determine significant adverse effects of short-acting beta 2 agonists with clinical repercussions, and assess bronchodilator response in extreme-old-age patients who undergo the spirometry test. METHODS: This is a cross-sectional and retrospective study. The sample was extracted from the database (spirometer and respiratory questionnaire) of a pulmonary function service. Patients over 90 years old were included in the research, and we evaluated their bronchodilator response and its significant adverse effects that may have clinical repercussions related to the bronchodilator. RESULTS: A sample of 25 patients aged 92.12 ± 2.22 years (95% CI, 91.20 - 93.04), with a minimum age of 90 years and a maximum of 97 years and a predominance of females with 72% (18/25). The bronchodilator test was performed in 84% (21/25) of the patients. The bronchodilator response was evaluated in 19 of the 21 patients (90.47%) who underwent the bronchodilator test. Two tests did not meet the criteria of acceptability and reproducibility. No clinical adverse effects were observed with the bronchodilator medication (salbutamol) during or after the exam. CONCLUSIONS: Chronological age is not a limiting factor for the bronchodilator test, short-acting beta-2 agonists did not present adverse effects with significant clinical repercussion and were useful in the diagnosis and therapeutic guidance of extreme-old-age patients.

RESUMO OBJETIVOS: Avaliar se idade cronológica é um fator limitante para realizar prova broncodilatadora, determinar efeitos adversos significativos com repercussão clínica dos beta-2 agonistas de curta ação e avaliar a resposta broncodilatadora na espirometria, na velhice extrema. MÉTODOS: Estudo transversal, retrospectivo. Amostra extraída do banco de dados (espirômetro e questionário respiratório) de um serviço de função pulmonar. Incluídos na pesquisa pacientes com ≥90 anos, sendo avaliados a resposta broncodilatadora e efeitos adversos significativos com repercussão clínica ao broncodilatador. RESULTADOS: Amostra de 25 pacientes com idade de 92,12 ± 2,22 anos (IC 95%; 91,20 - 93,04), idade mínima de 90 anos e máxima de 97 anos, predominando o sexo feminino, com 72% (18/25). A prova broncodilatadora foi realizada em 84% (21/25) dos pacientes. A avaliação da resposta ao broncodilatador foi feita em 19 dos 21 pacientes (90,47%) que realizaram a prova broncodilatadora, uma vez que dois desses exames não preencheram os critérios de aceitabilidade e reprodutibilidade. A resposta broncodilatadora foi significativa em 10,52% (2/19) dos pacientes, ambos portadores de pneumopatia obstrutiva. Não foram observados efeitos adversos com repercussão clínica da medicação broncodilatadora (salbutamol) durante ou após sua realização. CONCLUSÕES: A idade cronológica não é um fator limitante para a realização da prova broncodilatadora, os beta-2 agonistas de curta ação não apresentaram efeitos adversos com repercussão clínica significativa e foram bastante úteis para auxiliar no diagnóstico e orientação terapêutica na velhice extrema.

[Occurrence of delayed symptoms after a challenge test with methacholine]. / Survenue de symptômes tardifs après un test de provocation par la méthacholine.

There are few prospective studies available on the development of delayed symptoms following challenge tests with methacholine (MCT) at the currently recommended doses. The objective of this study was to describe the nature and frequency of respiratory symptoms suggestive of bronchospasm developing within 24hours after a MCT. The study was offered to adult patients who underwent MCT seen consecutively between June and October 2015. Following the test, a questionnaire adapted from the GINA asthma control questionnaire bearing on diurnal and nocturnal symptoms (cough, dyspnoea, wheeze and tightness), was delivered to the patient and the replies collected by telephone 24hours later. Of the 101 patients included (initial FEV1 2.82±0.79L), 46 (46 %) were MCT+ and 55 (54 %) MCT-. Among the MCT-, 4 (7 %) presented with immediate symptoms (S+) and 4 (7 %) with delayed symptoms. Among the MCT+ patients, 36 (78 %) presented with immediate symptoms (P<0.001 compared with the MCT- patients), and 39 (85 %) with delayed symptoms (P<0.001 compared with the MCT- patients). Delayed symptoms developed with a mean of 5h30 after the provocation test. Immediate and delayed symptoms were more frequent in subjects having significant non-specific bronchial hyper-reactivity. Informing patients of the risk of developing delayed symptoms seems useful and allows optimization of their management after a MCT.

Pro and Contra: Provocation Tests in Drug Hypersensitivity.

Drug provocation test (DPT) is the controlled administration of a drug to diagnose immune- or non-immune-mediated drug hypersensitivity and the last step for accurate recognition of drug hypersensitivity reactions when the previous diagnostic evaluations are negative or unavailable. A DPT is performed only if other conventional tests fail to yield conclusive results. In each clinical presentation, "to provoke or not to provoke" a patient should be decided after careful assessment of the risk-benefit ratio. Well-defined benefits of DPT include confirmative exclusion of diagnoses of drug hypersensitivity and provision of safe alternatives. However, disadvantages such as safety, difficulty in interpretations of results, lack of objective biomarkers, risks of resensitization, efficiency in daily practice, and lack of standardized protocols, are poorly debated. This review summarizes the current published research concerning DPT, with particular emphasis on the advantages and disadvantages of DPT in an evidence-based manner.

Estudio comparativo de los efectos secundarios de las pruebas de provocación bronquial para el diagnóstico de asma bronquial / Comparative study of the secondary effects of bronchial provocation testing todiagnose bronchialasthm. Asthma

INTRODUCCIÓN: según el algoritmo diagnóstico de la Guía Española de Manejo del Asma (GEMA), el diagnóstico de asma bronquial debe objetivarse mediante la realización de pruebas de provocación bronquial, ante la negatividad de las previas. Recientemente, se han introducido sustancias como el manitol, por lo que sería importante establecer los criterios de indicación y la seguridad para los pacientes, en relación con sustancias usadas habitualmente, como la metacolina. OBJETIVO: analizar la presencia de efectos secundarios y la tolerancia de los pacientes a las pruebas de provocación bronquial con metacolina y manitol para el diagnóstico de asma bronquial. MATERIAL Y MÉTODO: se analizaron 108 pacientes con sospecha clínica de asma bronquial, nunca estudiados y sin tratamiento previo. A todos se le realizaron, con un intervalo de 24 horas, ambas pruebas diagnósticas en orden aleatorio. Se excluyeron aquellos con algún criterio de contraindicación para la realización de espirometría, fumadores de >10 paquetes/año y aquellos con tratamiento reciente con corticoides inhalados u orales. Se recogieron los efectos adversos en cada paciente y se analizó si existían diferencias significativas por el test Chi cuadrado y test exacto de Fisher. RESULTADOS: el 88,9% de los pacientes presentaron algún tipo de efecto secundario en el test de manitol (más frecuente tos y disnea), frente al 52,8% en el test de metacolina. Independientemente de la positividad de ambas pruebas, se objetivó mayor frecuencia de tos, náuseas y cefalea durante la realización del test de provocación con manitol frente al de metacolina. CONCLUSIONES: hemos objetivado, en los mismos pacientes, una peor tolerancia a la prueba de provocación con manitol frente a la metacolina no relacionada con la positividad de la prueba

INTRODUCTION: Based on the diagnostic algorithm by GEMA (Guía Española de Manejo del Asma or Spanish Asthma Management Guide), the diagnosis for bronchial asthma must be confirmed through bronchial provocation testing, in the light of negative prior tests. Recently, substances such as mannitol have been introduced, in which case, it would be important to establish indication and safety criteria for patients with regards to usually used substances such as methacholine. OBJECTIVE: Analyze secondary effects and patient tolerance to bronchial provocation testing with methacholine and mannitol to diagnose bronchial asthma. Material and METHOD: 108 patients were analyzed, who were clinically suspected of having bronchial asthma, but never studied nor had they any prior treatment. All patients underwent, within a 24-hour interval, both diagnostic tests in random order. Those with some type of contraindication criteria to perform the spirometry were excluded, as were smokers of >10 packets/ year and those recently treated with inhaled or oral corticoids. The adverse effects in each patient were collected and analyzed whether or not there were significant differences based on a Chi Square Test and Fisher Extract Test. RESULTS: 88.9% of the patients presented some type of secondary effect in the test with mannitol (most frequently coughing and dyspnea), compared to 52.8% in the methacholine test. Independently of the positivity of both tests, greater coughing, nausea and headache were observed during the provocation test when mannitol was used instead of methacholine. CONCLUSIONS: We confirm that in the same patients, there is worse tolerance during the provocation test when mannitol is used than when methacholine is used. This fact is not linked to the positivity of the test

Determinants of nocebo effect during oral drug provocation tests

BACKGROUND: A 'nocebo' effect is defined as troublesome symptoms after the administration of placebo. The aim of this study was to determine characteristics of nocebo responses and related factors. METHODS: Patients with a reliable history of drug-induced hypersensitivity reactions subjected to placebo-controlled oral drug provocation tests and reacted to placebo, were consecutively included in this case-control study. Controls consisted of the randomly selected subjects who had a history of drug hypersensitivity reaction but did not react to placebo. A structured questionnaire was performed by an allergy specialist. RESULTS: There were 137 subjects (mean age: 43.10 ± 12.65 years), with nocebo and 91 subjects (42.38 ± 12.18 years) without any reaction to placebo. Most nocebo reactions (71.5%, n = 98) were classified as subjective, with local pruritus as the most common finding. A minority of nocebo reactions (11.7%,n = 16) were objective as cutaneous reactions including flushing and urticaria. Factors related with nocebo risks were university graduation (OR: 2.96, 95% CI: 1.27-6.93, p = 0.012) and non-atopy (OR: 2.12, 95% CI: 1.02-4.40, p = 0.043). In terms of the time of first and last historical reaction to drugs, each 1-unit (a month) increase in first reaction time (OR: 1.008, 95% CI: 1.00-1.02, p = 0.001) and last reaction time (OR: 1.019, 95% CI: 1.01-1.03, p < 0.001) were associated with increased nocebo risk. CONCLUSION: In conclusion, subjects with high education, non-atopy, and older drug hypersensitivity reactions history seem to be more likely to experience nocebo effect during oral drug provocation tests. These risk factors should be considered and managed accordingly to complete the drug provocation procedure successfully

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In vivo diagnosis of allergic diseases--allergen provocation tests.

The allergen challenge test has been the mainstay of diagnosis of allergic diseases for a long time since it offers a direct proof of the clinical relevance of a particular allergen for the allergic disease symptoms and severity. Standardisation and availability for daily practice (including safety issues) are still to be refined but most of the challenge tests have safely crossed the border from research tools to diagnostic tests available for daily practice for a well trained clinical staff.

Occupational asthma: an overview.

Occupational asthma is a form of asthma that is often under-diagnosed and under-reported. Unrecognized occupational asthma can lead to progression of disease and increased morbidity. The medical history is a critical element for establishing a diagnosis of OA. The history should include a detailed assessment of the workplace environment, the work process, changes in symptoms in and away from the workplace, and a review of relevant material safety data sheets that may provide clues regarding exposure(s) and the potential cause(s). Objective testing including spirometry pre- and post-bronchodilators, peak expiratory flow rate monitoring in and out of the workplace, provocation testing (i.e., methacholine challenge) to assess for airway hyperresponsiveness, and, if feasible, specific provocation by experienced personnel in a controlled setting to a suspected inciting agent are necessary for confirming a diagnosis. Skin or serologic testing for specific IgE to aeroallergens to assess the worker's atopic status is useful especially when considering certain forms of OA where atopy is a risk factor. Specialized laboratory testing may be useful for specific OA causes. It is important to correctly make the diagnosis of OA as the impact on the worker's future employment and earning power can be significantly affected.

Methacholine challenge testing: improved patient comfort with a 2-tiered protocol.

BACKGROUND: The methacholine challenge test (MCT) is a test of bronchial hyperreactivity used as an aid in the diagnosis of asthma. MCT results are reported as the provocation concentration at which the forced expiratory volume in 1 second (FEV1) decreases 20% (PC20). The requirement for a 20% or greater decrease in FEV1 results in precipitous decreases in FEV1 in some patients. OBJECTIVE: To improve MCT safety without compromising accuracy. METHODS: We performed a retrospective analysis of 879 consecutive MCTs (derivation cohort). A novel protocol for MCT was developed and validated in a cohort of 564 MCTs performed in a second institution. RESULTS: In comparison with a PC20 cutoff of less than 8 mg/mL, a provocation concentration at which the FEV1 decreases 10% (PC10) cutoff of 1 mg/mL or less has a sensitivity of 86%, a specificity of 98%, a positive predictive value (PPV) of 97%, and a negative predictive value (NPV) of 91%. We propose a novel 2-tiered protocol for MCT. If the PC10 is 1 mg/mL or less, bronchial hyperreactivity is present; if the PC10 is greater than 1 mg/mL, the test is continued until the provocative concentration is 8 mg/mL or a 20% decrease in FEV1 is achieved. Compared with the standard protocol, the proposed protocol has a sensitivity, specificity, PPV, NPV, and overall accuracy of 100%, 98%, 97.6%, 100%, and 99%, respectively. The modified protocol would have enabled us to avoid 26 of 42 cases (62%) in which a 40% or greater decrease in FEV1 occurred and would save 0.65 dose for every MCT performed. The 2-tiered protocol performed well in the validation cohort; sensitivity, specificity, PPV, NPV, and overall accuracy were 100%, 98%, 87%, 100%, and 98%, respectively. CONCLUSION: The proposed 2-tiered protocol is accurate, saves time, and avoids precipitous decreases in FEV1.

Safety of and cellular response to segmental bronchoprovocation in allergic asthma.

RATIONALE: Despite its incorporation into research studies, the safety aspects of segmental allergen bronchoprovocation and differences in cellular response among different allergens have received limited consideration. METHODS: We performed 87 segmental challenges in 77 allergic asthma subjects. Allergen dose was based on each subject's response to whole lung allergen challenge. Bronchoalveolar lavage was performed at 0 and 48 hours. Safety indicators included spirometry, oxygen saturation, heart rate, and symptoms. RESULTS: Among subjects challenged with ragweed, cat dander, or house dust mite, there were no differences in safety indicators. Subjects demonstrated a modest oxygen desaturation and tachycardia during the procedure that returned to normal prior to discharge. We observed a modest reduction in forced vital capacity and forced expiratory volume in one second following bronchoscopy. The most common symptoms following the procedure were cough, sore throat and fatigue. Total bronchoalveolar lavage fluid cell numbers increased from 13±4 to 106±108×10(4) per milliliter and eosinophils increased from 1±2 to 44±20 percent, with no significant differences among the three allergens. CONCLUSIONS: In mild allergic asthma, segmental allergen bronchoprovocation, using individualized doses of aeroallergens, was safe and yielded similar cellular responses.

[Inhalation therapy: provocation tests, infectious risks, acute bronchiolitis and ENT diseases. GAT aerosolstorming, Paris 2011]. / Aérosolthérapie: tests de provocation, risques infectieux, bronchiolites et pathologie ORL. Aérosolstorming du GAT, Paris 2011.

Communications from the 2011 meeting of the GAT are reported in this second article on the practical management of bronchial provocation tests and infectious risks associated with the use of nebulization. Recent advances on the role of nebulized hypertonic saline in the treatment of acute bronchiolitis in infants and of the nebulization in sinusal diseases are also reported.

Bronchial allergen challenge using the Medicaid dosimeter.

BACKGROUND: Bronchial allergen provocations are well established in asthma research. We evaluated the reproducibility of single-concentration, single-step allergen challenges in volunteers with grass pollen allergy. METHODS: Forty-seven subjects underwent bronchial challenges using the aerosol provocation system nebulizer (Medicaid Sidestream) with incremental doses of grass pollen to define the individual allergen dose that causes a 20% drop in FEV(1) (PD(20)FEV(1)). In 39 subjects this procedure was followed by single-step challenges. Early and late asthmatic responses were monitored, and increases in exhaled nitric oxide were measured before and 24 h after single-step challenges. RESULTS: After the first single-step challenge, the maximum drop in FEV(1) was 21.3% ± 8.0. A comparison of the drop in FEV(1) to the initial incremental challenge (29.7% ± 7.5) revealed an intraclass correlation of -0.30 (p < 0.05). In the second single-step challenge, the mean drop in FEV(1) was 20.9% ± 7.2. Compared with the first single-step challenge, the intraclass correlation was 0.37 (p < 0.05) and the 95% limits of agreement according to Bland and Altman were -17.5 to 18.1%. The increases in exhaled nitric oxide revealed substantial agreement in repeated single-step challenges (26.8 ppb ± 27.8 and 21.8 ppb ± 21.9, ICC 0.62, p < 0.001). CONCLUSIONS: The use of aerosol provocation system to calculate the PD(20)FEV(1) allergen is a timesaving procedure and is less prone to errors because only one dilution of the allergen is used. The repeatability in well-defined subjects is excellent to study the mechanisms of allergen-induced airway inflammation and the development of new treatments for allergic diseases.

Hospital admission for acute painful episode following methacholine challenge in an adolescent with sickle cell disease.

Asthma is associated with increases in sickle cell disease (SCD)-related morbidity and mortality. A thorough evaluation for asthma in children with SCD is important and may involve methacholine challenge (MCh). In this report, we present a 14-year-old male with SCD who was admitted for an acute painful episode following MCh. Pain events after MCh have not been previously reported in children with SCD. The risk-benefit ratio should be strongly considered prior to performance of MCh in this patient population, and all possible complications, including an acute painful episode, should be openly discussed with the parents and pediatric patient.

Pollen challenge study of a phototherapy device for reducing the symptoms of hay fever.

OBJECTIVE: The objective was to investigate the effect of intranasal phototherapy delivered by a phototherapy device (allergy reliever SN-206) on symptoms of hay fever (seasonal rhinitis) due to grass pollen in adults. This registered class IIA medical device had been on sale for 15 months with no adverse effects reported but there had been no assessment of efficacy. Previous research had indicated that phototherapy could alleviate symptoms of allergic rhinitis but no double-blind, placebo-controlled trails had been done. RESEARCH DESIGN AND METHODS: The trial is a double-blind, placebo-controlled grass pollen challenge conducted out of the pollen season, on 101 adult male and female hay fever sufferers. Subjects were assigned to placebo or active groups by stratified random sampling using responses to a baseline questionnaire. All subjects used active or placebo devices three times a day for 14 days before pollen challenge. Subjects were monitored for 2.5 h after challenge. MAIN OUTCOME MEASURES: Primary outcome measures were observed severity scores for sneezing, running eyes, running nose, and the amount of eosinophil cationic proteins (ECP) in nasal secretions. Secondary outcome measures were symptom scores by subject report (itching eyes, itching nose, itching throat, itching mouth/palate), and nasal peak inspiratory flow (PIFn) and peak expiratory flow (PEFn). RESULTS: Significant reductions in severity of symptom scores were found for sneezing, running nose, running eyes and itchy mouth/palate (p < or = 0.05). No significant differences were found in the results for itchy eyes, itchy nose, itchy throat, ECPs, PIFn and PEFn. No adverse events occurred. CONCLUSIONS: The results show that the device significantly reduced some hay fever symptoms. The study would have been improved if compliance was monitored electronically and if nasal congestion was monitored by report. The mode of action is unclear. The study does not consider long-term implications of the therapy.

Provoked models of asthma: what have we learnt?

Asthma is a chronic inflammatory disease of the airways characterized by physiological abnormalities of variable airflow obstruction and airway hyperresponsiveness (AHR) to a wide variety of physical and inhaled chemical stimuli and the presence of symptoms. AHR is measured by challenging the airways with a variety of agonists and naturally occurring stimuli, which results in constriction of the airway smooth muscle, leading to airway narrowing and airflow limitation. There are two distinct mechanisms by which the airways can narrow to a constrictor stimulus and these are defined by the pathways they take to induce AHR. Direct stimuli are pharmacological agents administered exogenously (such as histamine or methacholine) that act 'directly' on specific receptors on the bronchial smooth muscle to cause constriction. The other mechanism by which the airway can narrow is via the inhalation of indirect stimuli, which include natural stimuli, such as allergen or exercise, and pharmacological agents such as adenosine monophosphate and hyper-osmotic agents (e.g. hypertonic saline or dry powder mannitol). These stimuli induce airway narrowing 'indirectly' by causing the endogenous release of mediators of bronchoconstriction from airway inflammatory cells. Provoked models of asthma have been extremely valuable in understanding the pathobiology of asthma, in aiding diagnosis, in helping to clarify the mechanisms of actions of effective drugs and in the development of new entities to treat asthma. Some provoked models are valuable clinically, particularly those that measure direct AHR, while others, particularly allergen challenge, have been used in animal models and in humans to study the mechanisms of allergen-induced airway inflammation and the associated physiological changes, as well in the development of new drugs for asthma. An emerging role for measurements of AHR is in the evaluation of the optimal treatment for patients with asthma.