Chronic Asthma Severity Research Articles

The Effect of Acute and Chronic Asthma Severity on Pediatric Emergency Department Utilization

Our goal was to teach emergency department (ED) physicians how to use standardized criteria for diagnosing and classifying asthma severity and to describe the patterns of pediatric ED utilization of these criteria for classification of both acute and chronic severity. A health care provider education module was developed and implemented in 4 participating EDs in southeast Texas to educate ED physicians and health care providers on the diagnosis and acute and chronic severity classification of pediatric asthma patients. We undertook both retrospective (medical chart extraction) and prospective surveillance over a 2-year period of all children presenting to 1 of 4 EDs with acute asthma. Demographic characteristics, classification of severity, health care resource utilization, and primary physician contact information were collected. The health care provider educational intervention was provided for 84 different physicians. A subset of 16 physicians was randomly tested preintervention and postintervention. Mean mock-scenario scores at 2 weeks showed an improvement of 55.6%, which was sustained at retesting at 6 months. Over the 2-year period, 6222 individual pediatric ED encounters were entered into the surveillance database. The median age of presentation was 5 years. More than 32% of the patients in the study were uninsured. The majority of the patients in each category had asthma of mild severity: mild intermittent chronic (58.7%) and mild acute (53.9%). Physicians who completed a health care provider education module learned to effectively diagnose asthma and recognize standardized acute and chronic severity classifications. The majority of children with asthma who presented to the Texas Emergency Department Asthma Surveillance project's participating EDs were classified as having mild acute severity and mild intermittent chronic disease. Almost one third of these patients did not have health insurance.

Randomized Controlled Trial of Emergency Department Interventions To Improve Primary Care Follow-up for Patients With Acute Asthma

Emergency department (ED) visits for asthma are frequent and may indicate increased morbidity and poor primary care access. Our objective was to compare the effect of two interventions on primary care follow-up after ED treatment for asthma exacerbations. We performed a randomized controlled trial of patients 2 to 54 years old who were judged safe for discharge receiving prednisone, and who were available for contact at 2 days and 30 days. Patients were excluded if they were previously enrolled or did not speak English. Patients received usual discharge care (group A); free prednisone, vouchers for transport to and from a primary care visit, and either a telephone reminder to schedule a visit (group B); or a prior scheduled appointment (group C). Follow-up with a primary care provider for asthma within 30 days was the main outcome. Secondary outcomes were recurrent ED visits, subsequent hospitalizations, quality of life, and use of inhaled corticosteroids 1 year later. Three hundred eighty-four patients were enrolled. Baseline demographics, chronic asthma severity, and access to care were similar across groups. Primary care follow-up was higher in group C (65%) vs group A (42%) or group B (48%) [p = 0.002]. Group C intervention remained significant (odds ratio, 2.8; 95% confidence interval, 1.5 to 5.1) when adjusted for other factors influencing follow-up (prior primary care relationship, insurance status). There were no differences in ED, hospitalizations, quality of life, or inhaled corticosteroid use at 1 year after the index ED visit. An intervention including free medication, transportation vouchers, and appointment assistance significantly increased the likelihood that discharged asthma patients obtained primary care follow-up but did not impact long-term outcomes.

Measuring Asthma Severity: Instrument Refinement

The focus of this study is to evaluate a brief parent-report instrument, the Severity of Chronic Asthma (SCA) scale, that conforms to the national guidelines for assessing asthma. Convergent validity was found between the SCA and other measures related to asthma severity including an illness severity scale (How Bad is the Asthma?), asthma management scales for parents and children, and the pediatric quality-of-life scale. The SCA is a multidimensional scale with appropriate evidence of reliability and validity that may be a heuristic and effective measure in both clinical practice and research endeavors.

Update on Allergy Immunotherapy

This article summarizes and provides commentary regarding guidelines on the administration of immunotherapy (IT) for allergic airway disease. Recent investigations have provided important insights into the immunologic mechanism of IT and the prominent role of interleukin-10-producing regulatory T lymphocytes. The most important aspect of successful IT is the administration of an appropriate dose of an extract containing a sufficient concentration of the relevant allergen. This is largely possible now only with standardized extracts. When the major allergen content of successful IT extracts was quantified, efficacy was demonstrated across a surprisingly narrow concentration range (approximately 5-24 μg per injection), irrespective of the extract. This presumably reflects the concentration of an antigen that drives an immune response toward tolerance. It may be predicted that as major allergen content is quantified in currently nonstandardized extracts, effective IT will also be achieved by administering a dose in this range, in contrast to current practices involving fairly arbitrary dosing decisions. With the availability of nonsedating antihistamines, intranasal corticosteroids, and the leukotriene modifiers, inadequate pharmacologic response or intolerable side effects are less commonly the major indications for starting IT for allergic rhinitis (AR). However, with the recognition that a relatively short course (3-5 years) of IT can provide long-term immunomodulation and clinical benefit, a desire to avoid long-term pharmacotherapy and the associated high costs may be the primary indication for IT in AR cases. While evidence overwhelmingly supports the beneficial influences of IT in asthma cases, the positioning of IT for this disorder is not established. The observed prevention of asthma in children who have AR is intriguing, but further studies are required to assess the extent to which the prevalence and severity of chronic asthma will be reduced when these children reach adulthood. Similarly, safety issues overwhelmingly suggest that uncontrolled asthma is the greatest risk factor for mortality associated with IT and that IT therefore may be contraindicated for most patients who have inadequate pharmacologic responses or are unable to tolerate useful pharmacologic agents. Paradoxically, these are the patients for whom a response to IT may be most desirable.

Importance of the personal endotoxin cloud in school-age children with asthma

A number of studies have observed associations between the amount of endotoxin in urban dust and chronic asthma severity, but a direct relationship between personal exposure to household endotoxin and acute asthma worsening has not yet been defined. We sought to investigate the relationship between day-to-day changes in personal endotoxin exposure and asthma severity. In the winter and spring of 1999 through 2000, endotoxin exposures were monitored in asthmatic schoolchildren by using portable, as opposed to stationary, monitors designed to measure inhalable and respirable particulate matter less than or equal to 2.5 and 10 microm in diameter. Children were followed with daily measurements of FEV(1) and asthma symptoms. Over a 24-hour period, median daily personal endotoxin exposures ranged from 0.08 EU/m(3) (measured at a particulate matter size range </=2.5 microm in diameter) to 0.37 EU/m(3) (measured at a particulate matter size range </=10 microm in diameter). Personal exposures were significantly (P < .001) higher than endotoxin measurements from either indoor or outdoor stationary monitors. Moreover, individual exposures did not correlate with stationary measurements, suggesting that exposures derived from sources in close proximity to the children's personal activities might be better correlated with disease severity. Increases in personal endotoxin exposures were associated with decreased FEV(1) values and increased symptoms. These findings demonstrate the importance of using personal monitoring to both measure and correlate endotoxin exposure with asthma severity.

Chronic Asthma Severity Among Children Presenting to the Emergency Department with Asthma Exacerbations

Study Objectives: ED-initiated preventive interventions for asthma depend, in large part, on chronic asthma severity, as defined by the national asthma guidelines. For example, inhaled corticosteroids are preferred controller therapy for patients with persistent asthma but are not recommended for those with intermittent asthma. Our objective was to describe chronic asthma severity among children presenting to the ED with an asthma exacerbation.

Asthma Exacerbations in North American Adults: Who Are the “Frequent Fliers” in the Emergency Department?

<h3>Objective</h3> To characterize adult asthma patients according to frequency of emergency department (ED) visits in the past year. <h3>Design</h3> Adults presenting with acute asthma to 83 US EDs underwent structured interviews in the ED and by telephone 2 weeks later. <h3>Results</h3> The 3,151 enrolled patients were classified into four groups: those reporting no ED visits in the past year (27%), one to two visits (27%), three to five visits (25%), and six or more visits (21%). The number of ED visits (NEDV) was associated with older age, nonwhite race, lower socioeconomic status, and several markers of chronic asthma severity (all p < 0.001). NEDV was strongly associated with Medicaid insurance (17% among those with no visits, 22% with one to two visits, 30% with three to five visits, 39% with six or more visits; p < 0.001). NEDV was unrelated to gender or having a primary care provider (PCP). In a multivariate model, independent predictors of high ED use (six or more visits a year) were nonwhite race, Medicaid, other public, and no insurance, and markers of chronic asthma severity. Patients with six or more ED visits accounted for 67% of all prior ED visits in the past year. <h3>Conclusions</h3> High NEDV is associated with characteristics that may help with identification of "frequent fliers" in the ED. A better understanding of these characteristics may advance ongoing efforts to decrease asthma health-care disparities, including differential access to primary asthma care. National guidelines recommend specific ED treatments then referral to a PCP. Although longitudinal care is surely important, attempts to reduce frequent ED asthma visits may be better directed toward more specific preventive and educational needs.

Characterization of two polymorphisms in the leukotriene C4 synthase gene in an Australian population of subjects with mild, moderate, and severe asthma*1

BackgroundThe cysteinyl-leukotrienes (cys-LTs) are proinflammatory mediators that are important in the pathophysiology of asthma. LTC4 synthase is a key enzyme in the cys-LT biosynthetic pathway, and studies in small populations have suggested that a promoter polymorphism (A-444C) in the gene might be associated with asthma severity and aspirin intolerance.ObjectiveWe sought to screen the LTC4 synthase gene for polymorphisms and to determine whether there is an association between these polymorphisms and asthma severity or aspirin sensitivity in a large, well-phenotyped population and to determine whether this polymorphism is functionally relevant.MethodsThe coding regions of the LTC4 synthase gene were screened for polymorphisms and the A-444C polymorphism was analyzed in a large Australian white adult population of mild (n = 282), moderate (n = 236), and severe asthmatic subjects (n = 86) and nonasthmatic subjects (n = 458), as well as in aspirin-intolerant asthmatic subjects (n = 67). The functional activity of the promoter polymorphism was investigated by transient transfection of HL-60 cells with a promoter construct.ResultsA new polymorphism was identified in intron 1 of the gene (IVS1-10c>a) but was not associated with asthma. Association studies showed that the A-444C polymorphism was weakly associated with asthma per se, but there was no association between the C-444 allele and chronic asthma severity or aspirin intolerance. A meta-analysis of all the genetic studies conducted to date found significant between-study heterogeneity in C-444 allele frequencies within different clinical subgroups. In vitro functional studies showed no significant differences in transcription efficiency between constructs containing the A-444 allele or the C-444 allele.ConclusionsOur data confirm that, independent of transcriptional activity, the C-444 allele in the LTC4 synthase gene is weakly associated with the asthma phenotype, but it is not related to disease severity or aspirin intolerance.

Characterization of two polymorphisms in the leukotriene C 4 synthase gene in an Australian population of subjects with mild, moderate, and severe asthma

Background The cysteinyl-leukotrienes (cys-LTs) are proinflammatory mediators that are important in the pathophysiology of asthma. LTC 4 synthase is a key enzyme in the cys-LT biosynthetic pathway, and studies in small populations have suggested that a promoter polymorphism (A -444C) in the gene might be associated with asthma severity and aspirin intolerance. Objective We sought to screen the LTC 4 synthase gene for polymorphisms and to determine whether there is an association between these polymorphisms and asthma severity or aspirin sensitivity in a large, well-phenotyped population and to determine whether this polymorphism is functionally relevant. Methods The coding regions of the LTC 4 synthase gene were screened for polymorphisms and the A -444C polymorphism was analyzed in a large Australian white adult population of mild (n = 282), moderate (n = 236), and severe asthmatic subjects (n = 86) and nonasthmatic subjects (n = 458), as well as in aspirin-intolerant asthmatic subjects (n = 67). The functional activity of the promoter polymorphism was investigated by transient transfection of HL-60 cells with a promoter construct. Results A new polymorphism was identified in intron 1 of the gene (IVS1-10c>a) but was not associated with asthma. Association studies showed that the A -444C polymorphism was weakly associated with asthma per se, but there was no association between the C -444 allele and chronic asthma severity or aspirin intolerance. A meta-analysis of all the genetic studies conducted to date found significant between-study heterogeneity in C -444 allele frequencies within different clinical subgroups. In vitro functional studies showed no significant differences in transcription efficiency between constructs containing the A -444 allele or the C -444 allele. Conclusions Our data confirm that, independent of transcriptional activity, the C -444 allele in the LTC 4 synthase gene is weakly associated with the asthma phenotype, but it is not related to disease severity or aspirin intolerance.

Acute Asthma Among Adults Presenting to the Emergency Department: The Role of Race/Ethnicity and Socioeconomic Status

To investigate racial/ethnic differences in acute asthma among adults presenting to the emergency department (ED), and to determine whether observed differences are attributable to socioeconomic status (SES). Prospective cohort studies performed during 1996 to 1998 by the Multicenter Airway Research Collaboration. Using a standardized protocol, researchers provided 24-h coverage for a median duration of 2 weeks per year. Adults with acute asthma were interviewed in the ED and by telephone 2 weeks after hospital discharge. Sixty-four North American EDs. A total of 1,847 patients were enrolled into the study. Black and Hispanic asthma patients had a history of more hospitalizations than did whites (ever-hospitalized patients: black, 66%; Hispanic, 63%; white, 54%; p < 0.001; patients hospitalized in the past year: black, 31%; Hispanic, 33%; white, 25%; p < 0.05) and more frequent ED use (median use in past year: black, three visits; Hispanic, three visits; white, one visit; p < 0.001). The mean initial peak expiratory flow rate (PEFR) was lower in blacks and Hispanics (black, 47%; Hispanic, 47%; white, 52%; p < 0.001). For most factors, ED management did not differ based on race/ethnicity. After accounting for several confounding variables, blacks and Hispanics were twice as likely to be admitted to the hospital. Blacks and Hispanics also were more likely to report continued severe symptoms 2 weeks after hospital discharge (blacks, 24%; Hispanic, 31%; white, 19%; p < 0.01). After adjusting for sociodemographic factors, the race/ethnicity differences in initial PEFR and posthospital discharge symptoms were markedly reduced. Despite significant racial/ethnic differences in chronic asthma severity, initial PEFR at ED presentation, and posthospital discharge outcome, ED management during the index visit was fairly similar for all racial groups. SES appears to account for most of the observed acute asthma differences, although hospital admission rates were higher among black and Hispanic patients after adjustment for confounding factors. Despite asthma treatment advances, race/ethnicity-based deficiencies persist. Health-care providers and policymakers might specifically target the ED as a place to initiate interventions designed to reduce race-based disparities in health.

Reduced eosinophil apoptosis in induced sputum correlates with asthma severity.

This study was carried out to investigate the relationship between induced sputum eosinophil apoptosis and clinical severity score, airway obstruction and symptom scores in patients with chronic stable asthma. Altogether, 41 chronic stable asthmatic subjects of varying severity defined by Aas score and 17 control subjects underwent spirometry, symptom questionnaire and successful sputum induction. Sputum was processed and cytospins prepared for light microscopy to determine normal and apoptotic eosinophils. Mild asthmatic subjects had a significantly lower percentage sputum eosinophils and a significantly higher eosinophil apoptotic ratio (AR) than moderate or chronic severe asthmatics. Severe asthmatic subjects had a significantly greater age, duration of asthma and sputum eosinophil count x mL(-1) than mild asthmatic subjects. Asthmatic subjects' symptom scores, severity scores and age inversely correlated with AR and the percentage of sputum eosinophils. Baseline forced expiratory volume in one second inversely correlated with percentage sputum eosinophils and positively correlated with AR. The study demonstrates a relationship between reduced sputum eosinophil apoptosis and increased clinical severity of chronic stable asthma, providing additional evidence that eosinophil apoptosis may be important in the resolution of eosinophilic airway inflammation in asthma.

Body Mass Index and Asthma Severity Among Adults Presenting to the Emergency Department

Among adults presenting to the emergency department (ED) with acute asthma, we sought to determine the prevalence of obesity, and the relation of body mass index (BMI) to asthma severity in this high-risk population. Multicenter, prospective cohort study. Twenty-six North American EDs. Five hundred seventy-two patients aged 18 to 54 years presenting with acute asthma. None. A standardized interview assessed demographic characteristics, asthma history, and details of the current asthma exacerbation. Data on ED medical management and disposition were obtained by chart review. Three of four asthmatic patients were either overweight (BMI, 25 to 29.9; 30%) or obese (BMI, > or =30; 44%). Normal weight/underweight, overweight, and obese patients did not differ on several markers of chronic asthma severity; obese subjects tended to rate symptoms more severely and to use more inhaled beta-agonists in the 6 h hours prior to ED presentation despite a significantly higher initial percentage of predicted peak expiratory flow (PEF) [44%, 45%, and 51%, respectively; p < 0.05]. The three BMI groups responded similarly to acute therapy in the ED, with all groups demonstrating reversible airway obstruction. The sex distribution by BMI group differed markedly (p < 0.001), with women less often overweight (40% vs 24%) and more often obese (30% vs 52%). Since women were more likely have a higher initial PEF (45% vs 53%, p < 0.001), we stratified by sex to further examine the relation of BMI to asthma severity. The observed BMI-asthma associations were due largely, but not entirely, to confounding by sex. Despite lingering concerns about the veracity of "asthma" among obese individuals, asthma exacerbations among obese and nonobese adults were remarkably similar. Potential differences (eg, in symptom perception, use of inhaled beta-agonists before ED presentation, initial PEF rate) were due, in large part, to confounding by sex.

Is Asthma an Infectious Disease?: Thomas A. Neff Lecture

Respiratory tract infections caused by viruses, Chlamydia, and Mycoplasma have been implicated in the pathogenesis of asthma. Of these respiratory pathogens, viruses have been demonstrated to be associated with asthma epidemiologically in at least two ways. First, during infancy, certain viruses have been implicated as potentially being responsible for the inception of the asthmatic phenotype. Second, in patients with established asthma, particularly children, viral upper respiratory tract infections play a significant role in producing acute exacerbations of airway obstruction that may result in frequent outpatient visits or in hospitalizations. For infections with other microbial agents, recent attention has focused on Chlamydia and Mycoplasma as potential contributors to both exacerbations and the severity of chronic asthma in terms of loss of lung function or medication requirements. In an attempt to address the question posed in the title, this article will briefly review these various associations as they pertain to the pathogenesis of asthma in both children and adults.

Role of viruses and atypical bacteria in exacerbations of asthma in hospitalized children: a prospective study in the Nord-Pas de Calais region (France).

We studied the role of viruses and atypical bacteria in children hospitalized with exacerbated asthma by a prospective study of children with acute asthma admitted to the Department of Pediatrics in Lille, and to 15 hospitals in the Nord‐Pas de Calais region, from October 1, 1998–June 30, 1999. We included children aged 2–16 years with active asthma, defined as three or more recurrent episodes of reversible wheezing. The severity of asthma and of asthmatic exacerbations was recorded. Immunofluorescence assays (IFA) on nasopharyngeal secretions (NPS), serological tests, or both, were used for detection of influenza virus, respiratory syncytial virus (RSV), adenovirus, parainfluenza virus, and coronavirus. Polymerase chain reaction (PCR) assays on NPS were used for rhinovirus and enterovirus. Serological tests for Chlamydia pneumoniae and Mycoplasma pneumoniae were performed. A control group of asymptomatic asthmatic outpatients was examined for respiratory viruses (using IFA and PCR). Eighty‐two symptomatic children (mean age, 7.9 years) were examined. Viruses were detected in 38% (enterovirus, 15.8%; rhinovirus, 12%; RSV, 7.3%). Serological tests for atypical bacteria were positive in 10% of patients (C. pneumoniae, 5%; M. pneumoniae, 5%). Among the 27 control subjects (mean age, 7.9 years), one PCR was positive for enterovirus. There was no correlation between severity of chronic asthma or asthmatic exacerbations and the diagnosis of infection. Atypical bacterial pathogen infections were linked with prolonged asthmatic symptoms. In conclusion, we confirmed the high incidence of viral infection in acute exacerbations of asthma, especially enteroviruses or rhinoviruses. Persistent clinical features were more frequently associated with atypical bacterial infections, suggesting that these infections should be investigated and treated in cases of persistent asthmatic symptoms. Pediatr Pulmonol. 2003; 35:75–82. © 2003 Wiley‐Liss, Inc.

Categorizing asthma severity and monitoring control of chronic asthma

Categorizing asthma severity and monitoring control of chronic asthma

Categorizing asthma severity and monitoring control of chronic asthma.

Asthma is a distressing disease, affecting up to 8% of the US population and causing considerable morbidity. Effective management of asthma requires accurate categorization of asthma severity and effective methods for monitoring the activity of the disease with treatment. Currently, symptoms, lung function, and requirements for corticosteroid treatment are the most accepted factors used for asthma severity categorization. Measures of airway hyperresponsiveness, particularly the use of methacholine, may provide additional information regarding the duration of asthma. Assessing airway inflammation using either sputum eosinophilia or exhaled nitric oxide levels has added little to clinical methods for determining asthma severity, but may be useful in monitoring the activity of the disease.

Prospective multicenter study of relapse after treatment for acute asthma among children presenting to the emergency department

Objective: Single-center studies have reported varying relapse rates after treatment of patients with acute asthma. We determined the relapse rate after emergency department (ED) treatment in a cohort of children. Design: This was a prospective inception cohort study performed during 1997-1998. Setting: The study was performed in 44 EDs including both general and pediatric centers. Patients: Children (n = 1184) aged 2 to 17 years who had been admitted to EDs, with acute asthma restricted to 881 patients discharged from the ED. Main results: Two weeks after discharge, families were telephoned to determine relapse. Follow-up data were available for 762 (86%) of the children with a 10% incidence of relapse. On univariate analysis several factors were associated with relapse including current medications and markers of asthma severity. On multivariate analysis the factors associated with relapse were age (OR 1.4 per 5-year increase), use of second-line asthma medications (OR 3.7), exposure to cigarette smoke (OR 0.5), and ED visits within the past year (OR 1.2 per 5 ED visits). Conclusions: The incidence of relapse among children is lower than that observed among adults and varies with age. Other risk factors such as frequent ED visits are likely markers of chronic asthma severity. Further research should focus on ways to decrease the relapse rate among patients at high risk. (J Pediatr 2001;138:318-24)

Are asthma medications and management related to deaths from asthma?

There is controversy about the role of beta-agonists in asthma mortality, and the impact of asthma management plans remains unclear. We compared blood beta-agonist levels in patients dying from asthma with those in controls, and estimated the risks associated with specific classes of medication and patterns of management. We identified 89 asthma deaths and recruited 322 patients presenting to hospitals with acute asthma. A questionnaire was administered to the next of kin in 51 cases, and to 202 controls. Blood drawn from 35 cases and 229 controls was assayed for salbutamol. Smoking, drinking, and family problems were significantly more likely among the cases of asthma death than among the controls. The two groups were reasonably well matched with regard to markers of chronic asthma severity. Cases of asthma death were significantly less likely than controls to use a peak flow meter. Written action plans were associated with a 70% reduction in the risk of death. Use of nebulized bronchodilators or oral steroids was significantly more likely in cases of asthma death. Mean blood salbutamol concentrations were 2.5 times higher in cases of asthma. The use of oral steroids for an attack of asthma reduced the risk of death by 90%. More widespread adoption of written asthma management plans, with less reliance on beta-agonists and closer medical supervision, should reduce asthma mortality.

HRCT Findings of Asthmatic Children under Maintenance Therapy

Purpose: The purpose of this study was to evaluate the HRCT findings of bronchial asthma during maintenance bronchodilator therapy and to determine whether there were irreversible bronchial changes occurred in pediatric patients with this condition. Materials and Methods: HRCT findings of the lung in 21 asthmatic children [14 boys and 7 girls aged between 3.5 and 13.8 (mean : 7.7) years] who were receiving maintenance bronchodilator therapy were retrospectively studied. At the time of CT examination, 16 were receiving nonsteroid bronchodilator therapy only, and five were receiving both bronchodilator and steroid therapy. Thirteen patients were defined as allergic and eight were nonallergic. The clinical severity of chronic asthma was graded as severe in seven cases, and moderate in 14. The duration of the disease ranged from 4 months to 6 years (mean 3.2 years). HRCT was performed in 19 cases for evalvation of the atelectasis, hyperinflation, and prominent bronchovascular bundles seen on plain radiographs, and in two cases for evaluation following acute exacerbation. A CT W-2000 scanner (Hitachi Medical Co. Tokyo, Japan) was used during the end inspiratory phase, and in addition, ten patients were s-canned during the expiratory phase. Scans were reviewed for evidence of bronchial thickening, bronchiectasis, emphysema, abnormal density, mucus plugs, and other morphological abnormalities. The presence of bronchial wall thickening or air trapping was evaluated according to the duration, severity and type of asthma. Results: Among the 21 patients, 7(33.3%) had normal HRCT findings, while in 14 (66.7%), bronchial wall thickening was demonstrated. Eleven of the 14 patients with bronchial wall thickening (78.6%) also had air trapping. No patient was suffering from bronchiectasis or emphysema. There were no statistically significant correlations between the presence of bronchial wall thickening or air trapping and the duration of the disease, its severity, or type of asthma. There was, however, a statistically significant correlation between bronchial wall thickening and air trapping (p

Case-control study of salmeterol and near-fatal attacks of asthma.

BACKGROUND: A case-control study was undertaken to investigate the hypothesis that the use of the long acting beta agonist salmeterol increases the risk of a near-fatal attack of asthma. METHODS:...