Negative Methacholine Challenge Test Research Articles

Standard technical specifications for methacholine chloride (Methacholine) bronchial challenge test (2023)

Standard technical specifications for methacholine chloride (Methacholine) bronchial challenge test (2023)

Presence of variable extrathoracic airflow limitation in patients with a negative methacholine challenge test

PurposeDetermine whether variable extrathoracic airflow limitation (VEAL) is observed in patients with negative methacholine challenge tests (MCT).MethodsElectronic medical records of patients undergoing MCT at Jesse Brown VA Medical Center between January 2017 and December 2019 were reviewed. Only patients with negative MCT were selected. Pertinent demographic, clinical, and pulmonary function tests (PFT) and MCT data were abstracted from each record. Spirometric flow-volume loops recorded during each test were inspected by one co-author to determine the first inhaled methacholine concentration at which FEF50/FIF50 was either > 1 or further increased if baseline FEF50/FIF50 after nebulized saline (vehicle) already exceeded 1. Student’s t-test was used for statistical analysis. P < 0.05 was considered statistically significant.ResultsOne hundred and twenty-seven consecutive patients with normal baseline PFT and negative MCT were identified. Thirteen patients (10.2%) had negative MCT and FEF50/FIF50 > 1 after testing. They were predominately obese (BMI, 31.3 ± 6.6), non-smoking (10), White (8) males (9) aged 51.3 ± 14.1 years (mean ± SD) referred for symptoms suggestive of asthma (n = 7) or for chronic cough (n = 6). Five had obstructive sleep apnea, three gastroesophageal reflux disease, and two chronic rhinosinusitis. FEF50/FIF50 increased significantly from 0.72 ± 0.21 after nebulized saline (vehicle) to 1.21 ± 0.13 after inhaled methacholine (p < 0.001). Median inhaled methacholine concentration eliciting these responses was 1.0 mg/mL (range, 0.25–16 mg/mL).ConclusionsVEAL is observed in a subset of patients with a negative MCT. This phenomenon should be recognized and reported to the referring healthcare providers and its clinical significance addressed as indicated.

Based on what parameters is safe to discontinuate inhaled corticosteroids in children with asthma?

Objective Remission of childhood asthma has not been widely studied. Patients in clinical remission continue to have some degree of bronchial hyperresponsiveness (BHR). The aim of this study was to investigate whether clinical parameters and lung function test are good parameters for discontinuation of inhaled corticosteroids (ICS) in asthmatic children, including patients with persistent BHR, as measured by the methacholine challenge test (MCT). Methods One year after discontinuation of inhaled corticosteroids (ICS), MCT was performed in a group of 40 asthmatic children to confirm or exclude BHR. In all patients, ICS treatment was discontinued based on the same parameters: symptoms, spirometry, daily PEF, and negative bronchodilator test. After achieving complete asthma control for at least 6 to 12 months, ICS treatment was stepped down and discontinued. Clinical course and spirometry were followed up after ICS discontinuation. Results Positive MCT was found in 50% of the patients. There was no statistically significant difference between the positive and negative MCT groups in age at initiation and discontinuation of ICS therapy, duration of ICS therapy, duration of stepping down period, FEV1, and PEF at the time of withdrawal of ICS and one year later. ICS treatment had to be restarted in two patients from the positive MCT group, due to recurrence of asthma symptoms. Conclusion Clinical parameters, normal spirometry, daily PEF values, and a negative bronchodilator test are good parameters for discontinuing ICS treatment in asthmatic children, even in patients with persistent BHR. Children should continue to be monitored, as symptoms may recur.

Airway hyperresponsiveness in patients with normal spirometry results and symptoms compatible with asthma: Primary care retrospective chart review.

To evaluate the proportion of patients with symptoms suggestive of asthma and normal lung function who exhibit airway hyperreactivity with methacholine challenge testing (MCT) in primary care. Retrospective chart review. Primary care lung clinic in Toronto, Ont. A total of 69 patients presenting to the lung clinic who had symptoms compatible with asthma, normal spirometry test results, and were referred for MCT. Descriptive statistics, frequency counts, independent t tests, and 2 tests were used to examine differences in the proportion of clinical and demographic variables identified in patients with or without a positive MCT result. Effect size was determined between MCT-positive and MCT-negative patients for both categorical ( coefficient) and continuous (Hedges g) data. Twenty-one patients (30.4%) had positive MCT results, and 48 patients (69.6%) had negative MCT results. Family history of asthma and reduced baseline and postbronchodilator forced expiratory volume in 1 second were associated with a positive MCT result. The findings of this study provide insight into the utility of simple spirometry for asthma diagnosis and the need to further clarify the role of MCT in the primary care setting.

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

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

Effect of lowering Methacholine Challenge Test cutoff in children

BackgroundThe diagnosis of asthma is based on clinical judgment, history of personal or familial atopy, and testing, typically with a methacholine challenge test (MCT). Guidelines suggest a provocation concentration that caused a decrease in forced expiratory volume in 1 second of 20% (PC20) cutoff of 4 mg/mL for a positive test result. ObjectiveTo investigate the effect of lowering the MCT PC20 cutoff from 8 to 4 mg/mL on the number of positive test results and the distribution of test results. MethodsA retrospective study was conducted at the Montreal Children's Hospital from January 1, 2006, through June 31, 2012, on patients referred by nonrespiratory physicians. A 2-minute tidal breathing dosing protocol was used, and the PC20 was calculated by linear interpolation. ResultsA total of 748 patients were tested using spirometry. A total of 134 (17.9%) had a negative MCT result, and 614 (81.1%) responded at 8 mg/mL or less. A total of 570 patients (92.8% of respondents) responded at a dose of 4 mg/mL or higher (median PC20 of 0.47 mg/mL), with the remainder (7.2% of respondents) responding at a dose between 4 and 8 mg/mL (median PC20 of 6.37 mg/mL). There was no difference in the number of positive test results between the sexes, regardless of cutoff. The sensitivity of MCT was 82.1% at a cutoff of 8 mg/mL and 76.2% at 4 mg/mL. With a pretest likelihood of asthma of 75%, the specificity was 71.2%. ConclusionIn a standard pediatric referral population, using a PC20 cutoff of 4 mg/mL provided a sensitivity of 76.2%, and only excluded 5.8% of all those referred for suspicion of asthma (7.2% of all test results were ≤8 mg/mL). This finding suggests that a PC20 of 4 mg/mL can reasonably be used as a cutoff for a positive MCT result in children.

A mutated vitamin D receptor in hereditary vitamin D-resistant rickets prevents induction of bronchial hyperreactivity and inflammation.

Previous studies have reported an association between vitamin D deficiency and asthma. Hereditary 1,25-dihydroxyvitamin D-resistant rickets (HVDRR) patients provide a natural model to assess the role of the vitamin D receptor (VDR) in regulating human lung immune responses and airway hyperreactivity. The aim of the study was to determine the role of the VDR on lung functions, airways, and systemic markers of inflammation and allergy in HVDRR patients. Thirteen HVDRR patients (aged 6-37 y) and 17 normal controls (aged 6-38 y) underwent spirometry, a methacholine challenge test (MCT), blood tests, allergy skin tests, determination of fractional exhaled nitric oxide, and measurement of serum and exhaled breath condensate cytokines, including IL-4, IL-5, IL-10, IL-17, and interferon-γ levels. All HVDRR patients had negative MCT results, whereas six controls (35.3%) had positive MCT results (P < .014). Serum IgE levels, eosinophil counts, and fractional exhaled nitric oxide and allergy skin test results were similar for the HVDRR patients and controls, as were the serum cytokine concentrations. The HVDRR patients had different cytokine levels in their exhaled breath condensate (increased IL-4 and IL-17 and decreased IL-5, IL-10, and interferon-γ levels) compared to the controls (P < .005). HVDRR patients show diverse exhaled cytokine profiles but seem to be protected against provoked bronchial hyperreactivity and clinical asthma. These findings suggest that an intact VDR has an important role in asthma pathophysiology.

Methacholine challenge is insufficient to exclude bronchial hyper-responsiveness in a symptomatic military population

Background: Bronchial hyper-responsiveness in a military population has been evaluated by direct and indirect challenge methods. We hypothesized that negative methacholine challenge testing (MCT) was not sufficient to exclude significant bronchial hyper-responsiveness in a symptomatic military population with exertional dyspnea. The purpose of our study was to identify bronchial hyper-responsiveness in symptomatic military recruits and active duty personnel with normal baseline spirometry and negative pharmacologic bronchoprovocation testing. Methods: We performed a retrospective single center electronic chart review of symptomatic service members with a negative MCT who completed a subsequent exercise challenge test (ECT). Results: ECT was positive in 45 (26.4%) of 171 subjects (98 recruits). Subjects with a positive ECT had lower baseline forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC) and FEV1/FVC than those with a negative ECT, and these differences were statistically significant. The mean drop in FEV1 with exercise challenge positive patients was 17.9 ± 9.2%, and the mean drop in FEV1 with MCT was significantly greater in exercise challenge positive patients (−9.5 ± 5.5 vs. −7.6 ± 5.5, p = 0.042). Exercise-induced bronchoconstriction (EIB) was observed in 41% of all recruits who subsequently did not complete training. Only 1 recruit subject of 28 with EIB completed training. Conclusions: Methacholine challenge is an insufficient screening test to detect bronchial hyper-responsiveness in a symptomatic military population. In military recruits, EIB is associated with training failure.

Vocal Cord Dysfunction Related to Combat Deployment

Several etiologies for vocal cord dysfunction (VCD), a syndrome of dyspnea, noisy breathing, and inspiratory vocal cord closure are suggested; there is no consensus on the predisposition to its development. One previously identified psychiatric etiology is combat stress. A retrospective review of military personnel evaluated at Landstuhl Regional Medical Center with a new VCD diagnosis post-deployment was conducted. Medical records were reviewed for existing pulmonary, sinus, esophageal, or psychiatric disorders and determined their VCD evaluation. Forty-eight patients were identified with VCD symptoms after combat deployment. For military personnel with VCD, symptoms were associated with several etiologies. Fifty-two percent reported symptoms were related to high stress/anxiety, whereas 39% reported symptoms during exercise; 16% had onset with acute respiratory illness and 7% were trauma related. The combination of a truncated inspiratory flow volume loop and negative methacholine challenge had a 72% positive predictive value. Common etiologies with VCD onset during deployment are anxiety/stress, exercise, or combination of factors. Spirometry with abnormal flow volume loop plus negative methacholine challenge testing offers a reasonable predictive value for diagnosing VCD. For deployed military with these findings, laryngoscopy for upper airway disorders should be conducted.

Eucapnic Voluntary Hyperventilation Is Superior to Methacholine Challenge Testing for Detecting Airway Hyperreactivity in Nonathletes

Introduction. Response to eucapnic voluntary hyperventilation (EVH) has not been compared with methacholine challenge testing (MCCT) in nonathletes being evaluated for dyspnea on exertion. Objective. To determine the airway response to EVH and MCCT in a population of nonathletes who exercise regularly but have symptoms with exertion. Methods. We reviewed records for all patients with exercise symptoms who underwent both EVH and MCCT. Presenting symptoms, comorbid diseases, and results of bronchoprovocation (BP) testing were recorded. This study was approved by the institutional review board at our hospital. Results. A total of 131 patients (mean age 32.3 ± 11.6, body mass index (BMI) 27.1 ± 4.7 kg/m2, 59.5% male) had an EVH, MCCT, and clinical evaluation performed. Overall, 37 (28.2%) patients had positive BP testing and met criteria for exercise-induced bronchoconstriction (EIB). There were 32 (24.4%) patients with a positive EVH, compared with only 11 patients with a positive MCCT (8.4%). There were 26 patients (19.8%) who had a positive EVH but a negative MCCT, and correlation between the two tests was poor to moderate (r = 0.11–0.57). A complaint of chest pain and younger age were independent predictors for a positive EVH, whereas a history of tobacco use and a decreased FEV1/FVC (forced expiratory volume in 1 s/forced vital capacity) predicted a positive MCCT. A previous diagnosis of asthma was an independent predictor for a response to either test. Discussion. In a population of nonathletes who exercise regularly and have symptoms with exertion, EIB is common. Correlation between EVH and MCCT in this population is poor, and although the tests are somewhat complementary, a large percentage of patients had a negative MCCT but a positive EVH. Conclusions. EIB is common in nonathletes with exercise-induced symptoms, and EVH is the preferred test for this population. Clinical implications. EIB is common in nonathletes who exercise regularly. In this population, MCCT will miss most patients with EIB, and MCCT and EVH show only poor-to-moderate correlation. Capsule summary: EVH has not been compared with MCCT in nonathletes without a diagnosis of asthma. Our study shows that the two tests are complementary in this population, but EVH is positive more often.

Bronchial reactivity and fractional exhaled NO in Crohn’s disease in the era of immunomodulating treatment

Our aim was to determine bronchial hyper-responsiveness (BHR) and fractional exhaled NO (FeNO) in a cohort followed and treated for Crohn's disease (CD) in a Pediatric Gastroenterology Unit. Consecutive children with CD were referred to the Pediatric Pulmonary Unit. Each patient completed a questionnaire, followed by spirometry, methacholine challenge test (MCT) and determination of FeNO. The control group included patients evaluated for functional cough who had negative MCT. Twenty-three children and young adults (mean age, 17.39 ± 2.96 years) with CD were compared to 24 healthy controls. 20/23 patients received immunomodulating treatment. Forced expiratory volume in 1 sec (FEV1) was significantly lower prior to (93.74 ± 10.81%, p = 0.009) and at the end of (78.91 ± 18.39%, p = 0.001) the MCT in the CD group compared with the control group (102.2 ± 10.477% and 95.33 ± 11.075%, respectively). Bronchial hyper-responsiveness was observed in 30.4% of patients with CD. FeNO levels were 15.37 ± 24.17 in CD and 11.38 ± 5.42 in the control group (p = 0.21). Neither the response to MCT nor FeNO levels were affected by the disease duration or activity index. In our series, BHR is less frequent than previously described in children with CD. We hypothesize that our finding could result from immunomodulating treatments or lower disease activity.

Patient Characteristics With Negative Methacholine Challenge Test and Its Impact on Management

Patient Characteristics With Negative Methacholine Challenge Test and Its Impact on Management

Bronchodilator Responsiveness Following a Negative Methacholine Challenge Test

Background: Ovarian sarcomas are poorly-studied rare tumors. Aim: To compare evolutions of sarcomas and epithelial ovarian carcinomas treated similarly. Patients and Methods: Eleven patients with ovarian sarcomas were retrospectively identified over 12 years at a single tertiary center, the Fundeni Clinical Institute, Bucharest. They were matched to similar patients with epithelial ovarian cancer treated in the same center, by the same surgical teams and according to the same principles in an attempt to clarify the survival difference according to histopathological type with interference given by the above-mentioned variables (surgeon, center, management strategies) eliminated. Results: For International Federation of Gynecology and Obstetrics (FIGO) stage II, overall survival for patients with sarcoma was 90.5 months while for those with epithelial carcinoma it was 113 months (p=0.048). For stage IIIB, overall survival for those with sarcomas was 62 months, while for those with epithelial carcinoma it was 81 months. For stage IIIC, overall survival for those with sarcoma was 14.5 months while it was 55 months for patients with epithelial ovarian cancer (p=0.007). For stage IV overall survival for sarcomas is 2 months while for epithelial cancer is 6 months (p=0.09). Conclusion: Survival and disease-free interval for patients with ovarian sarcoma are lower than those for patients with epithelial ovarian carcinoma. Re-laparotomy for ovarian sarcoma relapse does not seem to bring any survival benefit.

Negative methacholine challenge tests in subjects who report physician-diagnosed asthma

The frequency of adults reporting a history of asthma is rising. However, it is unclear whether this increased prevalence accurately demonstrates a rising trend or if it reflects an overall increase in asthma awareness. To determine the frequency of negative methacholine bronchoprovocation tests in adults who report physician-diagnosed asthma and to explore the clinical characteristics of subjects with negative tests. Data from methacholine challenge, spirometry, and physician assessment were analysed from 304 adults who reported physician-diagnosed asthma and responded to community-based advertising for asthma research studies. The clinical characteristics of methacholine-positive and -negative subjects were compared and a predictive model was tested to identify those characteristics associated with a negative test. Of the 304 subjects tested, 83 (27%) had a negative methacholine test. A negative test was positively associated with an adult-onset of symptoms (P<0.001), normal forced expiratory volume in 1 s (P<0.001), and having no history of exacerbation requiring oral steroids (P=0.03). Over half (60%) of those with a negative test reported weekly asthma-like symptoms (cough, dyspnoea, chest tightness, or wheeze), while 39% reported emergency department visits for asthma-like symptoms. A sizeable percentage of subjects who report physician-diagnosed asthma have a negative methacholine challenge test. These subjects are characterized by diagnosis of asthma as an adult and by normal or near normal spirometry. Caution should be exercised in the assessment and diagnosis of adults presenting with asthma-like symptoms, because they may not have asthma. Further diagnostic studies, including bronchoprovocation testing, are warranted in this patient group, especially if their spirometry is normal.

Airway reactivity in children before and after stem cell transplantation

Stem cell transplantation (SCT) is associated with pulmonary complications. We encountered several children post-SCT with a clinical picture suggestive of airway hyper-reactivity (AHR) and evidence of reversible airway obstruction that was not reported pre-transplant.We evaluated the possibility of increased AHR as assessed by methacholine challenge test (MCT) following the course of SCT, and assessed a possible correlation between AHR and pulmonary complications.This was a prospective study evaluating consecutive patients referred for SCT to the Department of Pediatric Hemato-Oncology. Evaluation included pulmonary function test and MCT before and after SCT, and assessment of pulmonary complications.Twenty-one of 33 patients completed the study. The mean PC(20) was 14.3 +/- 4.1 mg/ml prior to SCT; afterward the mean PC(20) decreased to 11.2 +/- 5.6 mg/ml (P = 0.018). The number of patients with airway reactivity (PC(20) < or = 8 mg/ml) increased from 2/21 patients before SCT to 8/21 patients after SCT (P = 0.043; McNemar test with Yates correction). Pulmonary complications and hospitalization were recorded in 33.3% of the patients (7/21 patients): 62.5% of the patients (5 patients) with AHR compared to 15.4% (2 patients) in the group without AHR (P = 0.041; Fisher exact test). There were 10 hospitalizations among the 8 patients with positive MCT compared to 2 hospitalizations in 13 patients with negative MCT (median 1 vs. 0, P = 0.045; Mann-Whitney U-test).Increased airway reactivity was observed in our study following the course of SCT. Positive MCT after SCT may be associated with increased risk of pulmonary complications. Larger prospective studies are needed to evaluate the possible mechanisms responsible for increased AHR and the clinical importance of these findings.

Predictive Value of sGaw, FEF25 − 75, and FEV1 for Development of Asthma after a Negative Methacholine Challenge Test

Background. A 20% change in forced expiratory volume in 1 second (FEV1) during methacholine challenge testing (MCT) is a reliable marker of asthma. When the FEV1 decrease is < 20%, there is controversy whether other changes in flows and conductance may be useful. We conducted this study to determine whether changes in sGaw, FEF25 − 75, and FEV1 in a negative MCT could predict future occurrence of asthma over a 3-year period. Methods. A total of 100 consecutive patients with clinical suspicion of asthma but who had a negative MCT per ATS FEV1 criteria (< 20% FEV1 decline at 16 mg/mL of methacholine) performed by the 5-breath dosimeter method were analyzed. Two pulmonary fellows, blinded to MCT results, reviewed the patients' medical records. Patients were classified into one of three categories: asthmatic, unclear, and not asthmatic. Decreases in sGaw, FEF25 − 75, and FEV1 in the five groups were then retrieved. Analysis of variance (ANOVA) was used for data analysis. Results. Of 100 patients, 23 were excluded owing to lack of a 3-year follow-up. After complete data review, the number of patients (n) in each group was as follows: asthmatic (n = 15), unclear (n = 7), and not asthmatic (n = 55). sGaw and FEF25 − 75 decreases from the negative MCT could not predict asthma; however, decreases in FEV1 were associated with future asthma occurrence (sGaw p = 0.21, FEF25-75 p = 0.07, FEV1 p = 0.0009). Forty-three percent of the patients who had a 10% to 20% decline in FEV1 eventually developed asthma. Conclusion. Up to 20% of patients who have symptoms suggestive of asthma but a negative MCT can still develop asthma. Declines in sGaw and FEF25 − 75 in a negative MCT appear to have no clinical significance. A decrease in FEV1, especially 10% to 20%, is associated with the diagnosis of future asthma.

Bronchodilator Response After Negative Methacholine Challenge Test Predicts Future Diagnosis of Asthma

Background. Currently there are no reliable means to predict the likelihood of a subject with negative results from a methacholine challenge test (MCT) to be diagnosed with asthma in the future. We sought to determine whether the magnitude of the response to bronchodilator (BD) administered after a negative MCT has a predictive value for future asthma. Methods. Over a 5 –year period, starting from January 2004, the change in the forced expiratory volume in 1 second (FEV1) after inhaling BD (salbutamol) was recorded among subjects with negative MCT despite symptoms suggestive of asthma such as wheezing and dyspnea. Subjects with a significant response to BD (defined as improvement in FEV1 of more than 200 ml and 12%) were questioned for the presence of asthma on January 2009. Results. Overall 645 subjects (mean age 21.4 ± 2.3 years) underwent MCT. Negative MCT (defined as PC20 > 16 mg/mL) was noted in 482 (74.7%) patients of whom significant response to BD was identified in 35. Over a median observation time of 2.1 years, 11 of them (31.4% of the study population and 1.7% of the entire cohort) were subsequently diagnosed with asthma. Improvement of FEV1 by 20% predicted asthma with sensitivity, specificity, and positive predictive values of 86.9%, 66.6%, 83.3%, respectively, p = 0.0022. Conclusions. Our findings suggest that administration of BD after a negative MCT enhances the diagnostic accuracy of the challenge test as it identifies subjects who are likely to develop clinical asthma in the future.

Persistent airway inflammation and bronchial hyperresponsiveness in patients with totally controlled asthma

A proportion of asthmatic patients can achieve total control according to the Global Initiative for Asthma/National Institute of Health guidelines. The aim of this study was to investigate whether total control of asthma is accompanied by the remission of airway inflammation and bronchial hyperresponsiveness. We assessed the number of eosinophil and the levels of eosinophil cationic protein (ECP) and interleukin (IL)-5 in induced sputum and bronchial responsiveness to methacholine in 76 patients with totally controlled asthma in comparison with 30 current untreated asthmatics and 20 healthy subjects. We found significantly higher number of eosinophil and higher levels of ECP and IL-5 in the total control group than those in healthy subjects (6.9% +/- 3.6% and 1.3% +/- 1.1%, 129.0 +/- 53.8 mug/l and 48.9 +/- 20.4 mug/l, 22.1 +/- 15.2 mug/l and 10.6 +/- 5.2 mug/l, respectively; p < 0.001), but lower than those in current asthma group (16.2% +/- 8.6%, 362.2 +/- 151.6 mug/l, 50.6 +/-25.8 mug/l, respectively; p < 0.001). Sixty-five (85.5%) patients with totally controlled asthma showed positive methacholine challenge test. In the total control group, number of eosinophil and the levels of ECP and IL-5 in induced sputum of patients with negative methacholine challenge test were significantly lower than those in subjects with positive methacholine challenge test (p < 0.001), whereas sputum number of eosinophil and the levels of ECP and IL-5 in patients with negative methacholine challenge test and those of healthy subjects were similar (p > 0.05). The results of this study suggest that airway inflammation and bronchial hyperresponsiveness still persisted during total control of asthma.

Interrelationship between Asthma and Functional Bowel Disease

Gastrointestinal abnormalities have been reported in subjects with bronchial asthma. The aim of this study was to evaluate the presence of irritable bowel syndrome (IBS) in subjects with bronchial asthma. 380 asthmatic patients were selected for body mass index (BMI), sex, and age, before undergoing both methacholine challenge test (MCHt) and skin prick tests. 195 asthmatic patients (51.3%) were positive to MCHt, while 185 (41.6 %) were negative. We also found that 17 (8.7%) of the 276 patients with positive MCHt, and 22 (11.8%) of the 185 patients with negative MCHt were affected by IBS. Therefore, there was no statistical significance between positive MCHt tests and IBS. The results do not demonstrate an interrelationship between asthma and IBS.

Irritable Bowel Syndrome and Bronchial Hyperresponsiveness: Is There a Link?

Background/Aim: Many studies have demonstrated a high prevalence of bronchial hyperresponsiveness in patients with irritable bowel syndrome (IBS). The aim of this 24-month prospective study was to evaluate the prevalence of IBS in asthmatic patients. Methods: We analyzed 623 asthmatic patients that were evaluated for body mass index, sex, and age before undergoing both a methacholine challenge test (MCHt) and skin prick tests. Results: We found that 276 asthmatic patients (44.3%) were positive on the MCHt, while 347 (55.7%) were negative. We also found that 27 (9.7%) of the 276 patients with a positive MCHt and 44 (12.7%) of the 347 patients with a negative MCHt were affected by IBS. Therefore, there was no statistically significant difference between positive MCHt tests and IBS. The PC₂₀ (mean provocation concentration of methacholine producing a 20% reduction in forced expiratory volume in 1 s ≤16 mg/ml) in all patients tested was 8.64 ± 2.58 mg/ml, being 8.75 ± 2.52 and 8.55 ± 2.32 mg/ml for males and females, respectively. Conclusions: These results do not demonstrate a relationship between MCHt and IBS. However, a relationship might still exist in a subpopulation of patients whose symptoms worsen by stress.