Small airway impairment and bronchial hyperresponsiveness in asthma onset

Purpose

Our study tried to find a relationship between baseline FEF_25-75% and airway hyperresponsiveness (AHR) and whether a greater FEF_25-75% impairment may be a marker of a more severe hyperresponsiveness in subjects with normal FEV1 and FEV1/FVC and suggestive asthma symptoms. Besides, we tried to asses a FEF_25-75% cut-off value to identify hyper-reactive subjects.

Methods

4,172 subjects (2,042 M; mean age: 38.3±14.9; mean FEV1 % predicted: 100.5±12.7 and FEV1/FVC: 85.4±6.8) were examined after performing a methacholine (Mch) test. All subjects reported a symptom onset within 3 years before the test. Subjects with PD20<400 or >400 µg were arbitrarily considered affected by moderate/severe and borderline AHR, respectively.

Results

PD20 values were 213 (IQR:86-557), 340 (IQR:157-872) and 433 (IQR:196-1032) µg in subjects with baseline FEF_25-75≤50%, FEF_25-75 between 50 and 70% and FEF_25-75>70% respectively (P<0.0001). Only in moderate/severe hyper-reactive subjects (excluded borderlines), PD20 was lower in the FEF_25-75≤50% subgroup than in the 1 with FEF_25-75>70%. The hyperreactive subjects percentage, was higher in those with FEF_25-75≤50% and lower in those with FEF_25-75>70% (P<0.0001). FEF_25-75<50% (compared to FEF_25-75>70%) was a higher AHR risk factor, especially in subjects with moderate/severe AHR (OR: 2.18 [IQR:1.41-3.37]; P<0.0001). Thresholds yielding the highest combined sensitivity/specificity for FEF_25-75% were 75.19 (area under curve [AUC]: 0.653) and 74.95 (AUC:0.688) in subjects with PD20<2,400 and <400 µg respectively. FEV1, FVC, and FEV1/FVC measured in subjects with different FEF_25-75≤50%, FEF_25-75>50 and ≤70% or FEF_25-75>70% levels were similar both in normoreactive and hyperreactive subjects.

Conclusions

At asthma onset, reduced baseline FEF_25-75 values with normal FEV1 and FEV1/FVC may predict AHR. Detectable predictive cut-off values do not exist because even normoreactive subjects can show lower FEF_25-75 values. Furthermore, a greater FEF_25-75 reduction may be associated to a more severe AHR, suggesting a possible FEF_25-75 role in the management of asthma when FEV1 and FEV1/FVC are normal.

Persistent airflow obstruction in young adult asthma patients

BACKGROUND

Lung function determined by spirometry and the severity of dyspnea correlate weakly in asthma patients. We attempted to determine the risk factors in asthma patients having persistent airway obstruction despite of having only mild subjective symptoms, and to examine the possibility of improving FEV1 by treating asthma on the basis of the bronchodilator change in FEV1.

METHODS

We examined asthma patients in their 20s and who visited Sagamihara National Hospital for the first time over a period of four years, by reviewing their clinical records. They underwent tests on the bronchodilator change in FEV1 and a test of airway hyperresponsiveness to histamine dihydrochloride.

RESULTS

One hundred thirty-eight subjects (mean age, 25.6 years; 51 males, 87 females; current smoking, 30.4%; history of childhood asthma, 48.6%) were enrolled. Among them, 18.8% (26/138) showed persistent airway obstruction (postbronchodilator FEV1/FVC (%) <80%). Using the multiple logistic regression model, we found that history of childhood asthma and smoking history were the significant isolated risk factors for persistent airway obstruction. Moreover, we determined that the factors associated with the reversibility of airway obstruction in asthma patients without subjective symptoms were history of childhood asthma.

CONCLUSIONS

In this study, patients not undergoing treatment for asthma were examined. History of childhood asthma and smoking history may be the risk factors for persistent airway obstruction in the asthma patients with mild subjective symptoms. Tests on the bronchodilator change in FEV1 should be performed in patients with history of childhood asthma and smoking history, even if they have only mild subjective symptoms.

Improving asthma care for African American children by increasing national asthma guideline adherence

INTRODUCTION

Children, particularly African American children, bear a disproportionate burden of asthma and are at highest risk for associated morbidity and mortality. The under-utilization of the National Asthma Education and Prevention Program (NAEPP) guidelines across all demographics and the under use of inhaled corticosteroids (ICS) as controller therapy in these children are well-documented. The primary aim of this study was to increase health care provider (HCP) adherence to the NAEPP guidelines by means of a guideline reminder tool, the Multi-colored Simplified Asthma Guideline Reminder, consequently increasing the prescription of ICS in this population.

METHOD

This study had a pre-experimental design with descriptive analysis.

RESULTS

The Multi-colored Simplified Asthma Guideline Reminder was effective in increasing HCP adherence to the NAEPP guidelines as evidenced by increased use of ICS as controller therapy.

DISCUSSION

Despite the increasing prevalence and burden of asthma in African American children, the associated prescriptive use of ICS has not increased substantially in the past decade. The greatest obstacle in the scope of improving asthma outcomes is the underuse of ICS by HCPs.

The response to bronchodilators in adults is not predictive of bronchial-hyperreactivity

BACKGROUND

In some subjects with suspected asthma who have normal spirometry, administration of bronchodilators (BD) improves expiratory flow rates. The predictive value of this phenomenon in adults is not known.

OBJECTIVES

To evaluate the predictive value of the response to BD for bronchial hyper-responsiveness (BHR) using the metacholine challenge test (MCT). Patients and methods. The study population included 62 non-smoking adult patients (41.9% women) 29.5 +/- 15.5 years of age (range 18-64 years) with suspected asthma with normal spirometry that underwent MCT within 1 week. The response to BD (200 mu g inhaled salbutamol) was compared between subjects with positive and negative MCT using cutoff levels of provocative concentrations of metacholine causing a 20% decrease in forced expiratory volume in 1 second (FEV(1)) (PC(20)) of 4 and 8 mg/mL.

RESULTS

Mean (+/- SD) baseline FEV(1) was 87.8 +/- 12% of predicted. After BD administration the mean FEV(1) increased by 4.3 +/- 3.9%. The prevalence of BHR was 17.7% and 25.8% for PC(20) for PC(20) of 4 mg/mL and 8 mg/mL, respectively. The post-BD FEV(1) increment for subjects with positive and negative MCT tests was 3.9% +/- 3.3% versus 4.4% +/- 4.1%, respectively; p = 0.89, using cutoff of 4 mg/mL. The corresponding figures for cutoff of 8 mg/ml were 4.3% +/- 3.1% vs. 4.3% +/- 4.2%, respectively; p = 0.8465. There was no correlation between post-BD FEV(1) increment and PC(20) values in patients with positive MCT test for the above-mentioned cutoff levels (correlation coefficient r = 0.1645, p = 0.6289; and r = 0.2417, p = 0.4051, respectively).

CONCLUSIONS

In adults with suspected asthma who have normal spirometry, the response to BD cannot be used to predict BHR.

When should a reversibility test be performed on patients with early stages of asthma and normal spirometry?

Subjects with bronchial asthmatic symptoms, forced expiratory volume in 1 second (FEV(1)) and FEV(1)/forced vital capacity [FVC] > 80% could show a positive reversibility test with salbutamol in about 25% of the cases. The aim of this study was to evaluate if a limit functional value for spirometry exists where a reversibility test using salbutamol, over this limit, is not necessary to confirm the diagnosis of asthma. Four hundred patients (mean age 31.12 +/- 10.99) with asthmatic symptoms and normal spirometry (mean FEV(1) 96.06 +/- 11.82%, mean FEV(1)/FVC 98.89 +/- 6.03%) were recruited. The number of subjects with reversible airflow obstruction (RAO) was evaluated using the following different criteria of reversibility: FEV(1) and FVC >or= slant 12%, peak expiratory flow (PEF) >or= slant 15%, FEF(25 -75) >or= slant 35%, and at least one of these (ANY). In subjects with baseline FEV(1) > 100% (150 patients), 26 (17.3%) patients showed a FEV(1) increase > 12% and, among the criteria used, 45 patients (30%) showed ANY. In subjects with baseline FEV(1)/FVC > 100% (204 patients), 36 patients (17.6%) showed a FEV(1) increase > 12% and 53 patients (26.8%) showed ANY. In subjects with baseline FEF(25 -75) > 70% (209 patients), 26 (12.44%) and 49 (23.44%) patients, respectively, showed an increase in FEV(1) > 12%, and ANY. In 56 patients with baseline cut-offs (evaluated together) FEV(1) > 100%, FEV(1)/FVC > 100% and FEF(25-75) > 70%, 10 patients (17.85%) showed a RAO with ANY. FEV(1) > 121% or FEV(1)/FVC > 110.8% or FEF(25 -75) > 110% were cut-off values identified in this study where no RAO subjects were found over these limits. In conclusion, baseline FEV(1) > 100%, FEV(1)/FVC > 100% and FEF(25 -75) > 70% cannot be considered cut-offs where it is not necessary to perform a reversibility test with a bronchodilator over these limits. It is improbable to find a positive reversibility test using salbutamol in patients with asthmatic symptoms and FEV(1) > 121% or FEV(1)/FVC > 110.8% or FEF(25 -75) > 110% to confirm the diagnosis of asthma.

The prevalence of atopy and asthma among university freshmen in Seoul, Korea: association with obesity

The aims of this study were to investigate the prevalence of atopy, asthma, and obesity in university freshmen and to determine whether leptin is associated with bronchodilator reversibility in obesity. A total of 537 university freshmen completed International Study of Asthma and Allergies in Children (ISAAC) questionnaire and underwent skin prick testing and bronchodilator reversibility test. The prevalences of asthma, wheeze, and atopy were 10 (1.9%), 84 (15.6%), and 198 (36.9%), respectively. The mean (+/- SD) bronchodilator response (5.1 +/- 4.4%) was higher in the overweight/obese men than in the normal male subjects (3.7 +/- 3.2%, p < 0.05). The mean leptin level in the overweight/obese men was 5.55 +/- 3.48 ng/mL, which was significantly higher than that (2.78 +/- 1.65 ng/mL) of the normal male subjects. The prevalence of asthma among university freshmen is seriously under-diagnosed and leptin may play a role in bronchodilator reversibility in overweight/obese young men.

Bronchodilator response to adrenergic beta2-agonists: relationship to symptoms in an adult community

BACKGROUND

Wheeze and chest tightness has traditionally been associated with enhanced bronchial responsiveness. However, no community studies are available on the associations between bronchodilator response and respiratory symptoms among adults.

AIM

To examine how respiratory symptoms predict bronchodilator response.

METHODS

An age and gender stratified random sample of all adults aged 47-48 and 71-73 years in Bergen, Norway, were invited. The 3506 participants (69%) filled in questionnaires including nine symptoms and performed bronchodilator reversibility tests. Subjects without current anti-asthmatic medication performing acceptable reversibility tests were included in the analyses (n=3088).

RESULTS

A reversibility with FEV(1) increase 12% and 200 ml was obtained in 2% of middle-aged and 4% of elderly subjects (p=0.001). In multiple linear regression analysis bronchodilatation was positively associated with wheezing without cold (FEV(1) increase of 1.5%, 95% CI: (0.9, 2.2)% in all participants and 31 ml, 95% CI: (1, 61)ml in men only) and dyspnoea climbing two flights of stairs (0.9%, 95% CI: (0.5,1.4)% and 12 ml, 95% CI: (1,23)ml). Chronic cough predicted the response negatively (-0.7%, 95% CI: (-1.3,-0.1)% and -17 ml, 95% CI: (-32,-2)ml). In multiple logistic regression analysis morning cough predicted an FEV(1) increase 12% and 200 ml (OR: 1.8, 95% CI: (1.1,2.8)).

CONCLUSIONS

A small fraction of adults in a general population has bronchodilatation after salbutamol inhalation. "Wheezing without cold", "dyspnoea climbing two flights of stairs", and "morning cough" predict an increased bronchodilator response among subjects without current anti-asthmatic medications.