What is the Best Way to Diagnose Possible Asthma Patients with Negative Bronchodilator Reversibility Tests?

Objective: The best method and strategy for the diagnosis of asthma remains unclear, especially in patients with negative bronchodilator reversibility test (BDRT). In our study, we aimed to investigate the diagnostic yield of peak expiratory flow (PEF) variability for this patient group. Methods: A total of 50 patients with suspected asthma, all with negative BDR test, were included in the study. Demographic information and symptoms were recorded and PEF variability was monitored for 2 weeks. Metacolinbronchial provocation test (mBPT) was performed. Asthma was diagnosed when PEF variability ≥20% and/or positive mBPT was observed. Results: 30 of 50 patients were diagnosed with asthma. After 1 month, 17 patients were evaluated for treatment outcomes. The sensitivity and specificity of PEF variability for different cut-off values (≥20%, >15% and >10%) were 61.5-83.3, 88.5-62.5 and 100-16.7, respectively. One of the most important findings of our study was the absence of variable airflow limitation or airway hyper reactivity in 39% patients with a previous diagnosis of asthma. Multiple logistic regression analysis revealed that a low baseline FEF25-75 value was an independent predictive factor for the diagnosis of asthma (p= 0.05). Conclusion: The most efficient diagnostic test for asthma is still unclear due to many factors. Our study is one of the few studies on this subject. Although current diagnostic recommendations generally recommend a PEF variability of 10% for the diagnosis of asthma, this threshold may not be appropriate for the BDR-negative patient group. Our results suggest using a threshold value of <15% for PEF variability when excluding asthma and ≥20% when confirming the diagnosis of asthma in patients with clinically suspected but unproven reversibility. Furthermore, FEF25-75 is considered to be an important diagnostic parameter that should be included in diagnostic recommendations for asthma.

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

BACKGROUND: Some patients with asthma demonstrate normal spirometry and remain undiagnosed without further testing. OBJECTIVE: To 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). METHODS: Using 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. RESULTS: Of 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. CONCLUSIONS: Four 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.

Daily Inhaled Corticosteroids Treatment Abolishes Airway Hyperresponsiveness to Mannitol in Defence and Police Recruits.

Background: Airway hyperresponsiveness (AHR) is a key pathophysiological feature of asthma and causes exercise-induced bronchoconstriction (EIB). Indirect bronchial provocation tests (BPTs) (e.g., exercise, mannitol) aid to diagnose asthma and identify EIB. Daily inhaled corticosteroids (ICS) can abolish AHR caused by indirect stimuli. Where strenuous physical exertion is integral to an occupation, identification of those at risk of EIB is important and documentation of inhibition of AHR with ICS is required before recruitment. Methods/Objectives: A retrospective analysis was performed on 155 potential recruits with AHR to mannitol who underwent follow-up assessment after daily ICS treatment to determine the proportion that can abolish AHR using ICS and to determine any predictors of the persistence of AHR. Results: Airway hyperresponsiveness was abolished in the majority (84%, n = 130) over the treatment period (mean ± SD 143 ± 72days), and it was defined as the provoking dose of mannitol to cause a 15% fall in FEV1 (cumulative inhaled dose of mannitol to cause 15% fall in FEV1, PD15) improved from (GeoMean) 183 to 521 mg. Compared with recruits in whom AHR was abolished with daily ICS (i.e., no 15% fall in FEV1 to the maximum cumulative dose of mannitol of 635 mg), in those where AHR remained (16%, n = 25), baseline AHR was more severe (PD15: 85 mg vs. 213 mg, P < 0.001), baseline FEV1% was lower (89 vs. 96%; 95%CI:2-12, P=0.004), and they had a longer follow-up duration (180 vs. 136 days; 13-74, P = 0.006). Baseline FEV1% (adjusted odds ratio 0.85; 95%CI:0.77-0.93), FEV1/FVC (0.78; 0.67-0.90), FEF25-75% (1.15; 1.06-1.25), and airway reactivity to mannitol (%Fall/cumulative dose of mannitol multiplied by 100) (1.07; 1.03-1.11) predicted AHR remaining after daily ICS. Conclusion: Airway hyperresponsiveness to mannitol can be abolished after 20 weeks of daily treatment with ICS. Inhibition of AHR is likely due to attenuation of airway inflammation in response to ICS treatment. Increased airway reactivity and lower spirometry variables predicted the persistence of AHR. Thus, those with a slower response to daily ICS on AHR can potentially be identified at the commencement of monitoring ICS using inhaled mannitol.

Identifying bronchoconstriction from the ratio of diaphragm EMG to tidal volume.

BACKGROUND: A fall of ≥ 20 % in forced expiratory volume in the first second (FEV1) with a cumulative dose of histamine ≤ 7.8 µmol is considered to indicate bronchial hyperactivity, but no method exists for patients who cannot perform spirometry properly. Here we hypothesized that increases in respiratory central output measured by chest wall electromyography of the diaphragm (EMGdi-c) expressed as a function of tidal volume (EMGdi-c/VT) would have discriminative power to detect a 'positive' challenge test. METHODS: In a physiological study EMGdi was recorded from esophageal electrode (EMGdi-e) in 16 asthma patients and 16 healthy subjects during a histamine challenge test. In a second study, EMGdi from chest wall surface electrodes (EMGdi-c) was measured during a histamine challenge in 44 asthma patients and 51 healthy subjects. VT was recorded from a digital flowmeter during both studies. RESULTS: With histamine challenge test the change in EMGdi-e/VT in patients with asthma was significantly higher than that in healthy subjects (104.2 % ± 48.6 % vs 0.03 % ± 17.1 %, p < 0.001). Similarly there was a significant difference in the change of EMGdi-c/VT between patients with asthma and healthy subjects (90.5 % ± 75.5 % vs 2.4 % ± 21.7 %, p < 0.001). At the optimal cut-off point (29 % increase in EMGdi-c/VT), the area under the ROC curve (AUC) for detection of a positive test was 0.91 (p < 0.001) with sensitivity 86 % and specificity 92 %. CONCLUSIONS: We conclude that EMGdi-c/VT may be used as an alternative for the assessment of bronchial hypersensitivity and airway reversibility to differentiate patients with asthma from healthy subjects.

Pulmonary Function Testing in Work-Related Asthma: An Overview from Spirometry to Specific Inhalation Challenge.

Work-related asthma (WRA) is a very frequent condition in the occupational setting, and refers either to asthma induced (occupational asthma, OA) or worsened (work-exacerbated asthma, WEA) by exposure to allergens (or other sensitizing agents) or to irritant agents at work. Diagnosis of WRA is frequently missed and should take into account clinical features and objective evaluation of lung function. The aim of this overview on pulmonary function testing in the field of WRA is to summarize the different available tests that should be considered in order to accurately diagnose WRA. When WRA is suspected, initial assessment should be carried out with spirometry and bronchodilator responsiveness testing coupled with first-step bronchial provocation testing to assess non-specific bronchial hyper-responsiveness (NSBHR). Further investigations should then refer to specialists with specific functional respiratory tests aiming to consolidate WRA diagnosis and helping to differentiate OA from WEA. Serial peak expiratory flow (PEF) with calculation of the occupation asthma system (OASYS) score as well as serial NSBHR challenge during the working period compared to the off work period are highly informative in the management of WRA. Finally, specific inhalation challenge (SIC) is considered as the reference standard and represents the best way to confirm the specific cause of WRA. Overall, clinicians should be aware that all pulmonary function tests should be standardized in accordance with current guidelines.

Bronchial challenge test in patients with a history suggestive of bronchial asthma with normal spirometric studies.

BACKGROUND: Bronchial hyper-responsiveness (BHR) is the hallmark of bronchial asthma, characterized by clinical features of cough, wheeze, breathlessness and chest tightness which are confirmed by spirometry showing obstructive pattern and reversibility to bronchodilators. In individuals having features of bronchial asthma but normal spirometry, demonstration of BHR with bronchial challenge test (direct or indirect) confirms/ rules out the diagnosis. The aim of this study was to assess BHR in patients (methacholine challenge) with a history suggestive of bronchial asthma but normal spirometry and its role in diagnosis of bronchial asthma. METHODS: This study was conducted at tertiary care respiratory center. Patients having clinical features of bronchial asthma but spirometry not confirming obstructive disorder and or reversibility were included in the study. After written consent, methacholine challenge test with methacholine chloride and exercise spirometry was done in all patients as per the American Thoracic Society protocol. RESULTS: A total of 50 (n) patients were included in the study. Among them, 42 patients had clinical features suggestive of bronchial asthma but having normal spirometry and eight patients were diagnosed as they had bronchial asthma in the past but asymptomatic and off drugs were included in the study. At PC20 4mg/ml 32 (64%) patients had a positive test, 28(66%) symptomatic patients and four (50%) asymptomatic asthmatics. There were no significant side effects with methacholine test. CONCLUSION: Airway hyper-responsiveness is an important aspect of bronchial asthma and its demonstration with bronchial challenge (direct and indirect) test is an important diagnostic tool. Methacholine challenge test is a safe procedure to perform under supervision.

Functional Examination of the Upper and Lower Airways in Asthma and Respiratory Allergic Diseases: Considerations in the Post-SARS-CoV-2 Era.

Airway examination procedures can potentially transmit infectious diseases to patients and to the health care professionals who perform them via various mechanisms. The COVID-19 pandemic has halted most of the activity of the clinics and laboratories involved in assessment of lung and nasal function, and clear recommendations in this regard have been made. Today, we still do not know for sure what its consequences will be in the short or long term, since important gaps remain in our knowledge of aspects as fundamental as virus transmission mechanisms, pathophysiology, immune response, and diagnosis. In this review, we study the examination techniques used to assess patients with respiratory allergy, asthma, and associated diseases during this period and highlight their possible advantages and disadvantages. Therefore, we focus on exploring the entire upper and lower airways, from the perspective of the safety of both health professionals and patients and their specific characteristics. We also analyze the intrinsic value of these interventions in terms of diagnosis and patient management. The changing situation of COVID-19 may mean that some of the assertions presented in this review will have to be modified in the future. While we seek to ensure a consistently broad approach, some differences in operational details may apply owing to local regulations.

Eucapnic voluntary hyperventilation test decreases exhaled nitric oxide level in children.

BACKGROUND: Exhaled nitric oxide (FeNO) measurements and eucapnic voluntary hyperventilation (EVH) tests have been used as diagnostic tools for asthma. Data on the impact of hyperventilation on the level of FeNO are limited. AIM: We aimed to evaluate whether EVH tests affect the level of FeNO in children aged 10-16 years. METHODS: A total of 234 children aged 10-16 years had a 6-min EVH test performed. In total, FeNO values for 153 of 234 children were measured before the test and within 15 min after the test. According to a baseline FeNO level of 20 ppb, children were divided into two groups: those with low values (FeNO < 20 ppb) and those with high values (FeNO ≥ 20 ppb). RESULTS: The median age of the children was 13.4 years (interquartile range 12.3-15.3 years); 58% were boys and 42% were girls. Of these children, 51% were sensitized to aeroallergens. In 101 of 153 children (66%), the FeNO values decreased after the EVH test. In children with low and high baseline levels, the median level of FeNO decreased after the EVH test: 10.5 ppb before versus 9.5 ppb after (p < .011), and 31.0 ppb before versus 28.0 ppb after (p < .011), respectively. The decrease in FeNO after EVH test was not associated with induced bronchoconstriction expressed as a change in FEV1 (Rs  = .19). CONCLUSIONS: The EVH test decreases FeNO levels. Therefore, FeNO should be measured before an EVH test is performed.

Effects of plant features on symptoms and airway inflammation in compost workers followed over 18 months.

This study investigated the plant features associated with increased irritation symptoms and levels of inflammation markers among compost workers (CWs). Ninety CWs were followed over 18 months, using questionnaires on respiratory symptoms, fractional exhaled nitric oxide measurements, spirometry, a methacholine bronchial challenge test, and quantification of specific immunoglobulins E (IgE) and G. CWs in plants processing the highest quantities of waste exhibited more airway irritation symptoms. So did the CWs in partially and fully indoor plants as compared to those in plants entirely outdoors. Working in sewage sludge versus green waste plants and having a high level of exposure were associated with higher levels of different IgE. The duration of employment decreased the FEV1 by 16 ml per year. Working in an indoor plant is linked to symptoms and inflammation markers in CWs.

Evaluation of clinically and physiologically atypical asthma: If it doesn't wheeze it may still be asthma.

OBJECTIVE: Children with asthma-like symptoms may not clinically wheeze. The objectives of this study were to evaluate if children, without physician-documented wheeze, wheeze during bronchial-challenge-testing (BCT), and if measurements of O2Sat and respiratory rate during BCT improve the BCT sensitivity? METHODS: Seven hundred and twenty-four children, who were referred for suspicion of asthma, performed a BCT. Positive BCT was determined by the provocation concentration (PC) which resulted in a 20% decrease in FEV1 (PC20), (in those who were able to perform spirometry, group B), or (in those unable to perform spirometry, group A) a 50% increase in respiratory rate (PCRR), or a 5% decrease in oxygen-saturation (PCO2-Sat) or appearance of wheezing (PCwheeze). RESULTS: Five hundred and seven BCTs were positive: group A n = 89 age, median (IQR), 3 (2.5-3.7) years (17.6%), were unable to perform spirometry, and group B n = 418 age 10.7 (6.8-15.6) years (82.4%), were able to perform spirometry. Children, without physician-documented wheeze in the total population (groups A plus B), were more likely (65.5%) to have a positive BCT without wheeze compared with those with physician-documented wheeze (41.0%, P < 0.001). In group A, adding PCRR and PCO2-Sat increased BCT sensitivity by 23.6%. CONCLUSIONS: Many children in both groups did not wheeze despite reaching BCT endpoints. Children without physician-documented wheeze tended not to wheeze at BCT. This may result in clinical under-diagnosis of asthma if depending on the presence of wheeze. In young children, adding PCRR and PCO2-Sat substantially increases BCT sensitivity and may improve asthma diagnosis.

Effect of CPAP on airway reactivity and airway inflammation in children with moderate-severe asthma.

BACKGROUND AND OBJECTIVE: Asthma is characterized by airway hyperreactivity and airway inflammation. We previously demonstrated that adults with mild well-controlled asthma exhibited a marked decrease in airway reactivity (PC20 increased >2-fold) after using nocturnal continuous positive airway pressure (CPAP) for 1 week. If CPAP produces a similar suppression of airway reactivity in children with moderate-severe asthma, who require chronic use of corticosteroids, then this non-pharmacological therapy might provide a beneficial alternative or supplemental therapy in these subjects. METHODS: Children aged 8-17 years with moderate-severe asthma were treated with 4 weeks of nocturnal CPAP (8-10 cm H2 O) or sham CPAP (<2 cm H2 O). Adherence was monitored with a modem installed in the equipment or by memory cards. Airway reactivity, assessed by methacholine bronchial challenge, was measured prior to and following treatment. RESULTS: The percentage of subjects adherent to treatment was similar in both groups (19/27 CPAP vs 19/28 sham, ~70%). There was a tendency for PC20 to increase with treatment in both groups (3.0-5.3 mg/mL CPAP vs 3.2 to 4.3 mg/mL sham, P = 0.083); however, the change did not differ significantly between groups (P = 0.569). CONCLUSION: We found that the 4-week treatment with nocturnal CPAP did not produce a twofold suppression of airway reactivity in children with moderate-severe asthma.

Predicting asthma in older adults on the basis of clinical history.

BACKGROUND: The diagnosis of asthma is not always straightforward and can be even more challenging in older adults. Asthma is ideally confirmed by demonstration of variable expiratory airflow limitation. However, many patients with asthma do not demonstrate airflow obstruction nor show bronchodilator reversibility. We aimed to investigate predictors for a positive bronchial challenge test with methacholine in older adults being evaluated for asthma. METHODS: This is a diagnostic accuracy study with a cross-sectional design. Participants ≥60 years with suspected asthma and a negative postbronchodilator response on spirometry were included. All participants underwent a methacholine challenge test (MCT). We assessed the value of standard asthma screening questions and additional clinical questions to predict the MCT results. A multivariable logistic regression model was developed to assess the variables independently impacting the odds of a positive MCT result. RESULTS: Our study included 71 participants. The majority were female (n = 52, 73.2%) and the average age was 67.0 years. Those with a positive MCT (n = 55, 77.5%) were more likely to have wheezing or coughing due to allergens (n = 51, 92.7% vs. n = 12, 75.0%; P = 0.004) and difficulty walking several blocks (n = 14, 25.5% vs. n = 1, 6.3%, P = 0.009). After adjustment, having wheezing or coughing due to allergens (OR = 4.2, 95% CI 1.7-7.8, P = 0.012) remained the only significant independent predictor of a positive MCT. CONCLUSIONS: In older adults with suspected asthma, questioning about wheezing or coughing due to allergens provides a modest independent value to predict a MCT result in those who previously had a negative postbronchodilator response on spirometry.

[The usefulness of bronchial challenge tests in the diagnosis of occupational asthma]. / Ocena nadreaktywnosci oskrzeli i jej zastosowanie w diagnostyce astmy zwiazanej z praca.

Bronchial hyperresponsiveness (BHR) is the individual ability to respond with bronchoconstriction to a variety of specific and nonspecific stimuli which do not cause these symptoms among healthy subjects. Bronchial hyperresponsiveness is one of the hallmark features of asthma. The degree of bronchial hyperresponsiveness is variable among individuals with asthma and may correlate to its severity (the more severe asthma the higher bronchial hyperreactivity). Bronchial hyperresponsiveness is evaluated by performing bronchial provocation test (BPT). Provocation tests are classified - according to their mechanisms - into direct and indirect tests. Direct challenge tests are highly sensitive and they are used primarily to rule out asthma. In contrast, provocation tests with indirect stimuli are less sensitive but more specific to the direct tests; they are used generally to confirm the diagnosis of asthma and they allow for more accurate conclusions about inflammatory lesions in the case of a patient. Bronchial provocation tests play a significant role in occupational medicine. They are particularly relevant to be performed prior to employment, during periodic examinations, and to diagnose and monitor both occupational asthma and work-related asthma. This article presents selected bronchial provocation tests and their usefulness in the diagnosis of occupational asthma. Med Pr 2018;69(4):457-471.

Do airway inflammation and airway responsiveness markers at the start of apprenticeship predict their evolution during initial training? A longitudinal study among apprentice bakers, pastry makers and hairdressers.

BACKGROUND: The natural history of airway inflammation and symptoms in occupations at risk of asthma is still not fully understood. We aimed to study the evolution during apprenticeship of inflammation markers, bronchial hyperresponsiveness (BHR) and symptoms in at-risk subgroups as defined from measurements of markers made shortly after the start of training. METHODS: Respiratory symptoms, FEV1 and airway resistance post-bronchial challenge (MBC) test results, fractional exhaled nitric oxide (FeNO) measurements, and eosinophils in nasal lavage fluid were investigated in apprentice bakers, pastry-makers and hairdressers. Four visits were conducted: at the start of the training and every six months thereafter. Four baseline risk groups were defined, based on, (i) a high level of FeNO (NO), (ii) eosinophils > 1% (Eosino), (iii) a ≥ 15% decrease in FEV1 during the MBC test (HR), and (iv) a ≥ 50% increase in the resistance (Resist). The statistical analysis relied on mixed models. RESULTS: At baseline, the inflammation markers were related to the MBC markers. There was no evidence to suggest that the baseline risk groups predict a differential evolution of the airway inflammation and bronchial responsiveness markers, or the asthma-like symptoms considered. The baseline risk groups defined from MBC test predicted the levels of MBC markers. Similarly, the baseline risk groups based on eosinophilic inflammation predicted the levels of markers for eosinophilia. These results were similar in the three training tracks, with the exception of the FeNO levels which were not different according to the Eosino risk group. Twelve possible new asthma cases were identified, only the HR risk group predicted their occurrence. CONCLUSIONS: Among this young population, at-risk groups based on initial high levels of inflammation markers did not experience any worsening during the follow-up. However, initial BHR predicted consistently high levels of all markers considered and occurrence of possible asthma.

Realising the potential of various inhaled airway challenge agents through improved delivery to the lungs.

Inhaled airway challenges provoke bronchoconstriction in susceptible subjects and are a pivotal tool in the diagnosis and monitoring of obstructive lung diseases, both in the clinic and in the development of new respiratory medicines. This article reviews the main challenge agents that are in use today (methacholine, mannitol, adenosine, allergens, endotoxin) and emphasises the importance of controlling how these agents are administered. There is a danger that the optimal value of these challenge agents may not be realised due to suboptimal inhaled delivery; thus considerations for effective and reproducible challenge delivery are provided. This article seeks to increase awareness of the importance of precise delivery of inhaled agents used to challenge the airways for diagnosis and research, and is intended as a stepping stone towards much-needed standardisation and harmonisation in the administration of inhaled airway challenge agents.

Objective confirmation of asthma diagnosis improves medication adherence.

OBJECTIVE: The impact of diagnostic work-up in asthma management on medication redemption and probably also drug adherence is largely unknown, but we hypothesized that a confirmed diagnosis of asthma in a hospital-based out-patient clinic increases the willingness to subsequent medication redemption in a real life setting. METHODS: In a retrospective register-based study, 300 medical records of patients referred with possible asthma during one year were examined, of whom 171 had asthma (57%). One-year data on dispensed medicine was collected using the Danish Registry of Medicinal Product Statistics. Patients who had a positive asthma (e.g. bronchial challenge) were classified as verified asthma, whereas unverified asthma refers to doctor's diagnosis of asthma with negative or no diagnostic tests performed. RESULTS: 111 (65%) had a verified diagnosis and patients with verified asthma were more frequently prescribed new therapy compared to those with unverified asthma (88.9% vs. 65.0%, respectively, p < 0.001). No difference was found in first time redemption of prescriptions (72% vs. 64%, respectively, p = 0.3), whereas the second (52% vs. 27%, p = 0.001) and third or more asthma redeemed prescriptions (37% vs. 17%, p = 0.006) showed increased redemption of prescription and probably adherence in the verified compared with the unverified patients with asthma. Furthermore, the use of inhaled corticosteroid (ICS) was calculated as Percent Days Covered (PDC), which was higher in the verified group compared with the non-verified asthma group (88% vs. 30%, p = 0.004). CONCLUSION: Objective verification of a diagnosis of asthma using asthma tests was associated with an improved redemption of prescription.

Patterns of bronchial challenge testing in Canada.

BACKGROUND: Bronchial challenge testing (BCT) measures airway hyperresponsiveness; asthma guidelines recommend using BCT when symptoms manifest despite normal spirometry. Improper application of these guidelines commonly results in the misdiagnosis of asthma. Yet, statistics concerning BCT remain largely obscure. The current paper addresses this gap and explores how various health variables may elucidate adherence to asthma guidelines and patterns of BCT across Canadian provinces. METHODS: Using the Access to Information Act, medical financial claims for BCT (or equivalent procedures) were requested from each of the Canadian provinces and territories. Based on the available information (from provinces only), correlations between frequency of BCT claims and medical demographics (e.g., prevalence of respirologists, health expenditures) are reported. RESULTS: Controlling for population or for people with asthma, physicians from Québec claim four times more BCT per year than those in other provinces; physicians from Alberta close to eight-fold fewer. The number of respirologists per capita and BCT per capita correlated moderately, r(132) = 0.582, p < 0.001, [95% CI 0.421, 0.716]. Excluding "outliers" (i.e., British Columbia, Alberta, and Saskatchewan) greatly strengthened this correlation, r(87) = 0.930, p < 0.001, [95% CI 0.883, 0.958]. DISCUSSION: These findings demonstrate that provinces vary in their use of BCT. This result seems to stem, at least in part, from differences in the prevalence of respirologists. Interestingly, geographic region appears to wield a strong influence; in the correlation between number of tests and number of respirologists, physicians from Western provinces (i.e., Alberta, Saskatchewan, and British Columbia) administered fewer tests than their Eastern colleagues. Given the association between inadequate application of BCT and misdiagnosis of asthma, physicians should pay special attention to the Canadian guidelines when considering an asthma diagnosis.

Occupational asthma due to chamomile: case report. / Asma professionale da camomilla: descrizione di un caso.

We report the case of a worker employed in the packaging of herb infusions who came to our attention because he was suffering from breathing disorders caused by occupational exposure to chamomile dusts. The diagnostic procedure we followed highlighted a baseline lung function within the normal range, while the skin prick tests and the RAST test were positive to both seasonal aeroallergens and chamomile. To perform a specific bronchial provocation test, the patient was challenged in an exposure chamber with nebulization of an extract from chamomile flowers. This procedure, that we had already applied for other occupational allergens, induced in the patient an immediate bronchospastic type reaction, documented by a 17% reduction of FEV1 from baseline. It also produced a significant increase in bronchial non specific hyperresponsiveness and a remarkable rise of nitric oxide, in comparison with the pre exposure observed values. We concluded for a diagnosis of occupational asthma caused by chamomile.