Risk factors for death from asthma. Prairie Provinces Asthma Study Group

The Saudi initiative for asthma - 2024 update: Guidelines for the diagnosis and management of asthma in adults and children

The Saudi Initiative for Asthma 2024 (SINA-2024) is the sixth version of asthma guidelines for the diagnosis and management of asthma for adults and children that was developed by the SINA group, a subsidiary of the Saudi Thoracic Society. The main objective of the SINA is to have guidelines that are up-to-date, simple to understand, and easy to use by healthcare workers dealing with asthma patients. To facilitate achieving the goals of asthma management, the SINA Panel approach is mainly based on the assessment of symptom control and risk for both adults and children. The approach to asthma management is aligned for age groups: adults, adolescents, children aged 5-12 years, and children aged <5 years. SINA guidelines have focused more on personalized approaches reflecting a better understanding of disease heterogeneity with the integration of recommendations related to biologic agents, evidence-based updates on treatment, and the role of immunotherapy in management. The medication appendix has also been updated with the addition of recent evidence, new indications for existing medication, and new medications. The guidelines are constructed based on the available evidence, local literature, and the current situation at national and regional levels. There is also an emphasis on patient-doctor partnership in the management that also includes a self-management plan.

Heterogeneity of Airway Smooth Muscle Remodeling in Asthma

Rationale: Ventilatory defects in asthma are heterogeneous and may represent the distribution of airway smooth muscle (ASM) remodeling. Objectives: To determine the distribution of ASM remodeling in mild-severe asthma. Methods: The ASM area was measured in nine airway levels in three bronchial pathways in cases of nonfatal (n = 30) and fatal asthma (n = 20) and compared with control cases without asthma (n = 30). Correlations of ASM area within and between bronchial pathways were calculated. Asthma cases with 12 large and 12 small airways available (n = 42) were classified on the basis of the presence or absence of ASM remodeling (more than two SD of mean ASM area of control cases, n = 86) in the large or small airway or both. Measurements and Main Results: ASM remodeling varied widely within and between cases of nonfatal asthma and was more widespread and confluent and more marked in fatal cases. There were weak correlations of ASM between levels within the same or separate bronchial pathways; however, predictable patterns of remodeling were not observed. Using mean data, 44% of all asthma cases were classified as having no ASM remodeling in either the large or small airway despite a three- to 10-fold increase in the number of airways with ASM remodeling and 81% of asthma cases having ASM remodeling in at least one large and small airway. Conclusions: ASM remodeling is related to asthma severity but is heterogeneous within and between individuals and may contribute to the heterogeneous functional defects observed in asthma. These findings support the need for patient-specific targeting of ASM remodeling.

Requirements and limitations of imaging airway smooth muscle throughout the lung in vivo

Clinical visualization and quantification of the amount and distribution of airway smooth muscle (ASM) in the lungs of individuals with asthma has major implications for our understanding of airway wall remodeling as well as treatments targeted at the ASM. This paper theoretically investigates the feasibility of quantifying airway wall thickness (focusing on the ASM) throughout the lung in vivo by means of bronchoscopic polarization-sensitive optical coherence tomography (PS-OCT). Using extensive human biobank data from subjects with and without asthma in conjunction with a mathematical model of airway compliance, we define constraints that airways of various sizes pose to any endoscopic imaging technique and how this is impacted by physiologically relevant processes such as constriction, inflation and deflation. We identify critical PS-OCT system parameters and pinpoint parts of the airway tree that are conducive to successful quantification of ASM. We further quantify the impact of breathing and ASM contraction on the measurement error and recommend strategies for standardization and normalization.

Phenotype- and patient-specific modelling in asthma: Bronchial thermoplasty and uncertainty quantification

Theoretical models can help to overcome experimental limitations to better our understanding of lung physiology and disease. While such efforts often begin in broad terms by determining the effect of a disease process on a relevant biological output, more narrowly defined simulations may inform clinical practice. Two such examples are phenotype-specific and patient-specific models, the former being specific to a group of patients with common characteristics, and the latter to an individual patient, in view of likely differences (heterogeneity) between patients. However, in order for such models to be useful, they must be sufficiently accurate, given the available data about the specific characteristics of the patient. We show that, for asthma in particular, this approach is promising: phenotype-specific targeting may be an effective way of selecting patients for treatment based on their airway remodelling phenotype, and patient-specific targeting may be viable with the use of a clinically-plausible dataset. Specifically we consider asthma and its treatment by bronchial thermoplasty, in which the airway smooth muscle layer is directly targeted by thermal energy. Patient-specific and phenotype-specific models in this context are considered using a combination of biobank data from ex vivo tissue samples, CT imaging, and optical coherence tomography which allows more detailed resolution of the airway wall structures.

Airway remodelling with spatial correlations: Implications for asthma pathogenesis

Airway remodelling is a cardinal feature of asthma in which airways undergo structural changes - in particular, increased airway smooth muscle mass and total airway wall area. Remodelling has long been thought to have functional consequences in asthma due to geometric effects that can increase airway narrowing and luminal occlusion. Prior studies have examined the distribution of remodelling between and within patients, but none have yet considered the possibility for spatial correlations in airway remodelling. That is, is remodelling clustered locally, or interrelated along proximal and distal locations of the bronchial tree? In view of recent interest regarding airway remodelling produced by mechanical stimuli, we developed a mathematical model to examine whether spatial correlations in airway remodelling could arise due to cycles of bronchoconstriction and mechanotransduction. Further, we compared modelling predictions to the spatial distribution of airway remodelling in lungs from subjects with and without asthma. Results indicate that spatial correlations in airway remodelling do exist in vivo, and cycles of bronchoconstriction and mechanotransduction are one plausible mechanism for their origin. These findings offer insights into the evolution of airway remodelling in asthma, which may inform strategies for treatment and prevention.

Fatty airways: implications for obstructive disease

Epidemiological studies report that overweight or obese asthmatic subjects have more severe disease than those of a healthy weight. We postulated that accumulation of adipose tissue within the airway wall may occur in overweight patients and contribute to airway pathology. Our aim was to determine the relationship between adipose tissue within the airway wall and body mass index (BMI) in individuals with and without asthma.Transverse airway sections were sampled in a stratified manner from post mortem lungs of control subjects (n=15) and cases of nonfatal (n=21) and fatal (n=16) asthma. The relationship between airway adipose tissue, remodelling and inflammation was assessed. The areas of the airway wall and adipose tissue were estimated by point count and expressed as area per mm of basement membrane perimeter (Pbm). The number of eosinophils and neutrophils were expressed as area densities.BMI ranged from 15 to 45 kg·m^-2 and was greater in nonfatal asthma cases (p<0.05). Adipose tissue was identified in the outer wall of large airways (Pbm >6 mm), but was rarely seen in small airways (Pbm <6 mm). Adipose tissue area correlated positively with eosinophils and neutrophils in fatal asthma (Pbm >12 mm, p<0.01), and with neutrophils in control subjects (Pbm >6 mm, p=0.04).These data show that adipose tissue is present within the airway wall and is related to BMI, wall thickness and the number of inflammatory cells. Therefore, the accumulation of airway adipose tissue in overweight individuals may contribute to airway pathophysiology.

Unraveling a Clinical Paradox: Why Does Bronchial Thermoplasty Work in Asthma?

Bronchial thermoplasty is a relatively new but seemingly effective treatment in subjects with asthma who do not respond to conventional therapy. Although the favored mechanism is ablation of the airway smooth muscle layer, because bronchial thermoplasty treats only a small number of central airways, there is ongoing debate regarding its precise method of action. Our aim in the present study was to elucidate the underlying method of action behind bronchial thermoplasty. We employed a combination of extensive human lung specimens and novel computational methods. Whole left lungs were acquired from the Prairie Provinces Fatal Asthma Study. Subjects were classified as control (n = 31), nonfatal asthma (n = 32), or fatal asthma (n = 25). Simulated lungs for each group were constructed stochastically, and flow distributions and functional indicators (e.g., resistance) were quantified both before and after a 75% reduction in airway smooth muscle in the "thermoplasty-treated" airways. Bronchial thermoplasty triggered global redistribution of clustered flow patterns wherein structural changes to the treated central airways led to a reopening cascade in the small airways and significant improvement in lung function via reduced spatial heterogeneity of flow patterns. This mechanism accounted for progressively greater efficacy of thermoplasty with both severity of asthma and degree of muscle activation, broadly consistent with existing clinical findings. We report a probable mechanism of action for bronchial thermoplasty: alteration of lung-wide flow patterns in response to structural alteration of the treated central airways. This insight could lead to improved therapy via patient-specific, tailored versions of the treatment-as well as to implications for more conventional asthma therapies.

Patient-specific targeted bronchial thermoplasty: predictions of improved outcomes with structure-guided treatment

Bronchial thermoplasty is a recent treatment for asthma in which ablative thermal energy is delivered to specific large airways according to clinical guidelines. Therefore, current practice is effectively "blind," as it is not informed by patient-specific data. The present study seeks to establish whether a patient-specific approach based on structural or functional patient data can improve outcomes and/or reduce the number of procedures required for clinical efficacy. We employed a combination of extensive human lung specimens and novel computational methods to predict bronchial thermoplasty outcomes guided by structural or functional data compared with current clinical practice. Response to bronchial thermoplasty was determined from changes in airway responses to strong bronchoconstrictor simulations and flow heterogeneity after one or three simulated thermoplasty procedures. Structure-guided treatment showed significant improvement over current unguided clinical practice, with a single session of structure-guided treatment producing improvements comparable with three sessions of unguided treatment. In comparison, function-guided treatment did not produce a significant improvement over current practice. Structure-guided targeting of bronchial thermoplasty is a promising avenue for improving therapy and reinforces the need for advanced imaging technologies. The functional imaging-guided approach is predicted to be less effective presently, and we make recommendations on how this approach could be improved. NEW & NOTEWORTHY Bronchial thermoplasty is a recent treatment for asthma in which thermal energy is delivered via bronchoscope to specific airways in an effort to directly target airway smooth muscle. Current practice involves the treatment of a standard set of airways, unguided by patient-specific data. We consider the potential for guided treatments, either by functional or structural data from the lung, and show that treatment guided by structural data has the potential to improve clinical practice.

The Saudi Initiative for Asthma - 2019 Update: Guidelines for the diagnosis and management of asthma in adults and children

This is the fourth version of the updated guidelines for the diagnosis and management of asthma, developed by the Saudi Initiative for Asthma (SINA) group, a subsidiary of the Saudi Thoracic Society. The main objective of the SINA is to have guidelines that are up to date, simple to understand, and easy to use by healthcare workers dealing with asthma patients. To facilitate achieving the goals of asthma management, the SINA panel approach is mainly based on the assessment of symptom control and risk for both adults and children. The approach to asthma management is now more aligned for different age groups. The guidelines have focused more on personalized approaches reflecting better understanding of disease heterogeneity with integration of recommendations related to biologic agents, evidence-based updates on treatment, and role of immunotherapy in management. The medication appendix has also been updated with the addition of recent evidence, new indications for existing medication, and new medications. The guidelines are constructed based on the available evidence, local literature, and current situation at national and regional levels. There is also an emphasis on patient–doctor partnership in the management that also includes a self-management plan.

Relationship between chronic rhinosinusitis exacerbation frequency and asthma control

OBJECTIVES/HYPOTHESIS

To determine the association between the frequency of acute chronic rhinosinusitis (CRS) exacerbations (AECRS) and the degree of asthma control in asthmatic CRS patients.

STUDY DESIGN

Cross-sectional study.

METHODS

We prospectively recruited 108 asthmatic CRS patients as participants. Asthma control was assessed using the Asthma Control Test (ACT). The frequency of AECRS was assessed using three previously described indirect metrics for AECRS: the frequency of patient-reported sinus infections, CRS-related antibiotics use, and CRS-related oral corticosteroids use in the last 3 months. CRS symptom severity was measured using the 22-item Sinonasal Outcome Test (SNOT-22). Associations between ACT score and metrics for AECRS were performed using linear regression while controlling for clinical and demographic characteristics, including SNOT-22 score.

RESULTS

ACT score was significantly and negatively associated with the frequency of patient-reported sinus infections (adjusted linear regression coefficient [β] = -1.2, 95% confidence interval [CI]: -2.3 to -0.1, P = .033), CRS-related antibiotics courses (adjusted β = -1.4, 95% CI: -2.3 to -0.5, P = .004), and CRS-related oral corticosteroid courses (adjusted β = -1.5, 95% CI: -2.5 to -0.5, P = .004) in the last 3 months, independent of characteristics including SNOT-22 score. Poor asthma control could be detected using one or more sinus infections (70.6% sensitivity, 47.3% specificity), CRS-related antibiotics (50.0% sensitivity, 73.0% specificity), or CRS-related oral corticosteroids (58.8% sensitivity, 71.6% specificity) in the last 3 months.

CONCLUSIONS

AECRS are negatively associated with the level of asthma control in asthmatic CRS patients, independent of CRS symptom severity. These results highlight AECRS as a distinct clinical manifestation of CRS that should be routinely assessed in CRS patients.

LEVEL OF EVIDENCE

2c. Laryngoscope, 128:1033-1038, 2018.

Myofibroblasts are increased in the lung parenchyma in asthma

Background

Increased airway smooth muscle is observed in large and small airways in asthma. Semi-quantitative estimates suggest that cells containing alpha smooth muscle actin (α-SMA) are also increased in the lung parenchyma. This study quantified and characterized α-SMA positive cells (α-SMA+) in the lung parenchyma of non-asthmatic and asthmatic individuals.

Methods

Post-mortem sections of peripheral lung from cases of fatal asthma (FA), persons with asthma dying of non-respiratory causes (NFA) and non-asthma control subjects (NAC) were stained for α-SMA, quantified using point-counting and normalised to alveolar basement membrane length and interstitial area.

Results

α-SMA+ fractional area was increased in alveolar parenchyma in both FA (14.7 ± 2.8% of tissue area) and NFA (13.0 ± 1.2%), compared with NAC (7.4 ± 2.4%), p < 0.05 The difference was greater in upper lobes compared with lower lobes (p < 0.01) in both asthma groups. Similar changes were observed in alveolar ducts and alveolar walls. The electron microscopic features of the α-SMA+ cells were characteristic of myofibroblasts.

Conclusions

We conclude that in asthma there is a marked increase in α-SMA+ myofibroblasts in the lung parenchyma. The physiologic consequences of this increase are unknown.

Meta-analysis of asthma-related hospitalization in mepolizumab studies of severe eosinophilic asthma

BACKGROUND

Studies show that mepolizumab can reduce the frequency of clinically significant exacerbations in patients with severe eosinophilic asthma, compared with placebo. However, important events such as hospitalizations and emergency room visits are rare and difficult to characterize in single studies.

OBJECTIVE

We sought to compare hospitalization or hospitalization and/or emergency room visit rates in patients with severe eosinophilic asthma treated with mepolizumab or placebo in addition to standard of care for at least 24 weeks.

METHODS

This study was conducted and reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement. PubMed and the GSK Clinical Study Register were searched for suitable studies. The primary end points were the rate of exacerbations requiring hospitalization and the rate of exacerbations requiring hospitalization/emergency room visit. The proportion of patients with 1 or more event was also assessed. All mepolizumab doses were combined and individual patient-level data were analyzed.

RESULTS

Four studies (n = 1388) were eligible for inclusion. Mepolizumab significantly reduced the rate of exacerbations requiring hospitalization (relative rate, 0.49; 95% CI, 0.30-0.80; P = .004) and hospitalization/emergency room visit (relative rate, 0.49; 95% CI, 0.33-0.73; P < .001) versus placebo. Significant reductions of 45% and 38% were also observed for the proportion of patients experiencing 1 or more hospitalization and hospitalization and/or emergency room visit, respectively.

CONCLUSIONS

Mepolizumab approximately halved exacerbations requiring hospitalization and/or emergency room visits compared with placebo in patients with severe eosinophilic asthma. This treatment addresses a key outcome in a patient population with a high unmet need (GSK Study 204664).

The Saudi Initiative for Asthma - 2016 update: Guidelines for the diagnosis and management of asthma in adults and children

This is an updated guideline for the diagnosis and management of asthma, developed by the Saudi Initiative for Asthma (SINA) group, a subsidiary of the Saudi Thoracic Society. The main objective of SINA is to have guidelines that are up to date, simple to understand and easy to use by nonasthma specialists, including primary care and general practice physicians. SINA approach is mainly based on symptom control and assessment of risk as it is the ultimate goal of treatment. The new SINA guidelines include updates of acute and chronic asthma management, with more emphasis on the use of asthma control in the management of asthma in adults and children, inclusion of a new medication appendix, and keeping consistency on the management at different age groups. The section on asthma in children is rewritten and expanded where the approach is stratified based on the age. The guidelines are constructed based on the available evidence, local literature, and the current situation in Saudi Arabia. There is also an emphasis on patient-doctor partnership in the management that also includes a self-management plan.

The effect of asthma on the perimeter of the airway basement membrane

When comparing the pathology of airways in individuals with and without asthma, the perimeter of the basement membrane (Pbm) is used as a marker of airway size, as it is independent of airway smooth muscle shortening or airway collapse. The extent to which the Pbm is itself altered in asthma has not been quantified. The aim of this study was to compare the Pbm from the same anatomical sites in postmortem lungs from subjects with (n = 55) and without (n = 30) asthma (nonfatal or fatal). Large and small airways were systematically sampled at equidistant "levels" from the apical segment of the left upper lobes and anterior and basal segments of the left lower lobes of lungs fixed in inflation. The length of the Pbm was estimated from cross sections of airway at each relative level. Linear mixed models were used to investigate the relationships between Pbm and sex, age, height, smoking status, airway level, and asthma group. The final model showed significant interactions between Pbm and airway level in small (<3 mm) airways, in subjects having asthma (P < 0.0001), and by sex (P < 0.0001). No significant interactions for Pbm between asthma groups were observed for larger airways (equivalent to a diameter of ∼3 mm and greater) or smoking status. Asthma is not associated with remodeling of the Pbm in large airways. In medium and small airways, the decrease in Pbm in asthma (≤20%) would not account for the published differences in wall area or area of smooth muscle observed in cases of severe asthma.

The national review of asthma deaths: what did we learn and what needs to change?

KEY POINTS

The 2014 UK National Review of Asthma Deaths identified potentially preventable factors in two-thirds of the medical records of cases scrutinised45% of people who died from asthma did not call for or receive medical assistance in their final fatal attackOverall asthma management, acute and chronic, in primary and secondary care was judged to be good in less than one-fifth of those who diedThere was a failure by doctors and nurses to identify and act on risk factors for asthma attacks and asthma deathThe rationale for diagnosing asthma was not evident in a considerable number of cases, and there were inaccuracies related to the completion of medical certificates of the cause of death in over half of the cases considered for the UK National Review of Asthma Deaths.

EDUCATIONAL AIMS

To increase awareness of some of the findings of the recent UK National Review of Asthma Deaths and previous similar studiesTo emphasise the need for accurate diagnosis of asthma, and of the requirements for completion of medical certificates of the cause of deathTo consider areas for improving asthma care and prevention of attacks and avoidable deaths.

SUMMARY

Despite the development and publication of evidence-based asthma guidelines nearly three decades ago, potentially preventable factors are repeatedly identified in studies of the care provided for patients who die from asthma. The UK National Review of Asthma Deaths (NRAD), a confidential enquiry, was no exception: major preventable factors were identified in two-thirds of asthma deaths. Most of these factors, such as inappropriate prescription and failure to provide patients with personal asthma action plans (PAAPs), could possibly have been prevented had asthma guidelines been implemented. NRAD involved in-depth scrutiny by clinicians of the asthma care for 276 people who were classified with asthma as the underlying cause of death in real-life. A striking finding was that a third of these patients did not actually die from asthma, and many had no recorded rationale for an asthma diagnosis. The apparent complacency with respect to asthma care, highlighted in NRAD, serves as a wake-up call for health professionals, patients and their carers to take asthma more seriously. Based on the NRAD evidence, the report made 19 recommendations for change. The author has selected six areas related to the NRAD findings for discussion and provides suggestions for change in the provision of asthma care. The six areas are: systems for provision and optimisation of asthma care, diagnosis, identifying risk, implementation of guidelines, improved patient education and self-management, and improved quality of completion of medical certificates of the cause of death.

Risk of serious asthma exacerbations associated with long-acting beta agonists among patients with asthma: a retrospective cohort study

BACKGROUND

After the Serevent Nationwide Surveillance clinical trial, controversy has surrounded the safety of long-acting beta agonists (LABAs).

OBJECTIVE

Examine the association between LABAs and severe asthma exacerbations (SAEs).

METHODS

From a multistate Medicaid database, for the years 2002-2007, a total of 940,449 patients (age <40) with asthma were selected and divided into a cohort with newly-diagnosed asthma and one with pre-existing asthma. SAEs included asthma-related emergency department (ED) visits, hospitalizations, and intubations. Patients' asthma severity was determined based on medication regimen as suggested by the 2002 National Asthma Guidelines. Specific use of inhaled corticosteroids (ICSs), LABAs, ICS/LABA combination drugs, short-acting beta agonists (SABAs), and other drugs was tracked. Cox proportional hazard regressions were estimated to assess the risk of SAEs associated with patient severity, drug use, and covariates.

RESULTS

Compared to patients taking a SABA only, estimated SAE hazard ratios for newly diagnosed and pre-existing-asthma patients were as follows: 0.63 (95% CI 0.58-0.69) and 0.74 (0.70-0.79) for patients on a LABA without ICS, and 0.79 (0.77-0.81) and 0.90 (0.87-0.92) for those on a LABA/ICS single inhaler. Although hazard ratios were estimated to be similar for ED visits, LABA use was found to be positively associated with hospitalizations and intubations. Other key risk factors (P < .0001) included being African American, an alcohol/substance use disorder, pregnancy, and obesity.

CONCLUSION

Relative to SABA-only therapy, LABA use is associated with a lower risk of ED visit. Certain patients with asthma, such as pregnant women and African Americans, are particularly vulnerable to SAE risk of all types.

Quantitative assessment of elemental carbon in the lungs of never smokers, cigarette smokers, and coal miners

Inhalation exposure to particulates such as cigarette smoke and coal dust is known to contribute to the development of chronic lung disease. The purpose of this study was to estimate the amount of elemental carbon (EC) deposits from autopsied lung samples from cigarette smokers, miners, and control subjects and explore the relationship between EC level, exposure history, and the extent of chronic lung disease. The samples comprised three subgroups representing never smokers (8), chronic cigarette smokers (26), and coal miners (6). Following the dissolution of lung tissue, the extracted EC residue was quantified using a thermal-optical transmission (TOT) carbon analyzer. Mean EC levels in the lungs of the control group were 56.68 ± 24.86 (SD) μg/g dry lung weight. Respective mean EC values in lung samples from the smokers and coal miners were 449.56 ± 320.3 μg/g and 6678.2 ± 6162 μg/g. These values were significantly higher than those obtained from the never-smoker group. EC levels in the lung and pack-years of cigarette smoking correlated significantly, as did EC levels and the severity of small airway disease. This study provides one of the first quantitative assessments of EC in human lungs from populations at high relative risk for the development of chronic lung disease.

Ecologic analysis of asthma-related events and dispensing of inhaled corticosteroid- and salmeterol-containing products

BACKGROUND

An association between salmeterol use and serious asthma episodes or asthma-related mortality has been noted in 2 clinical trials; however, a causal relationship has not been established. To date, observational studies have not replicated this finding.

OBJECTIVE

To examine the relationship between number of prescriptions dispensed of salmeterol-containing products and inhaled corticosteroid (ICS)-containing products and the rates of asthma-related hospitalizations and mortality in the United States.

METHODS

In this ecologic study, annual age-adjusted rates of asthma-related hospitalization and asthma-related mortality from US population-based sources were graphed alongside annual number of prescriptions dispensed of salmeterol- and ICS-containing products by year from 1991 to 2004. We computed the Spearman rank correlations between number of prescriptions dispensed and serious events (asthma-related hospitalization rate, number of hospitalizations, asthma-related mortality rate, and number of asthma deaths).

RESULTS

During more than 14 years, while number of prescriptions dispensed of salmeterol-containing and ICS-containing products increased, age-adjusted asthma-related mortality rates declined and asthma-related hospitalization rates remained relatively stable. The number of asthma-related deaths has decreased steadily since the mid-1990s.

CONCLUSION

This study provides population-level evidence that asthma-related death rates declined and asthma-related hospitalization rates remained relatively constant for more than 14 years during a period of improvements in asthma management per treatment guidelines, including increased use of maintenance medications, such as ICSs and salmeterol.

Airway basement membrane perimeter distensibility and airway smooth muscle area in asthma

The perimeter of the basement membrane (Pbm) of an airway viewed in cross section is used as a marker of airway size because in normal lungs it is relatively constant, despite variations in airway smooth muscle (ASM) shortening and airway collapse. In vitro studies (McParland BE, Pare PD, Johnson PR, Armour CL, Black JL. J Appl Physiol 97: 556-563, 2004; Noble PB, Sharma A, McFawn PK, Mitchell HW. J Appl Physiol 99: 2061-2066, 2005) have suggested that differential stretch of the Pbm between asthmatic and nonasthmatic airways fixed in inflation may occur and lead to an overestimation of ASM thickness in asthma. The relationships between the Pbm and the area of ASM were compared in transverse sections of airways from cases of fatal asthma (F) and from nonasthmatic control (C) cases where the lung tissue had been fixed inflated (Fi; Ci) or uninflated (Fu; Cu). When all available airways were used, the regression slopes were increased in Fu and Cu, compared with Fi and Ci, and increased in Fu and Fi, compared with Cu and Ci, suggesting effects of both inflation and asthma group, respectively. When analyses were limited to airway sizes that were available for all groups (Pbm < 15 mm), the slopes of Fi and Fu were similar, but both were greater than Ci and Cu, which were also similar. It was calculated that the effect of asthma group accounted for 80% and inflation for 20% of the differences between Fi and Ci. We conclude that the effects of inflation on the relationship between Pbm and ASM are small and do not account for the differences observed in ASM between cases of asthma and nonasthmatic controls.

Variability in asthma: symptom perception, care, and outcomes

Asthma remains a global respiratory health concern. Substantial variations in asthma outcomes persist in Canada despite the dissemination of national management guidelines. Many factors and their interactions presumably contribute to variations in outcomes, including asthma prevalence, severity, symptom recognition, self-management behaviour, access to care, and management. This article reviews the physiology of symptom perception in asthma, specifically the role of dynamic lung hyperinflation (DH) on the perception of the intensity and quality of dyspnea in asthma, and the link between blunted perception and life-threatening asthma. Additionally, the magnitude and correlates of regional variation in emergency department visit rates and hospitalizations for asthma in Ontario are reviewed.

Feasibility of a national fatal asthma registry: more evidence of IRB variation in evaluation of a standard protocol

PURPOSE

Approximately 4,500 Americans die from asthma each year. Our objective was to determine the feasibility of creating a national fatal asthma registry to better understand this problem.Methods. Using a standard questionnaire, 18 state vital statistics departments and 22 medical examiners offices were contacted in 2001 to assess availability of fatal asthma data. Funding was obtained in 2002 to implement a fatal asthma registry. During 2003, the project was put on hold due to uncertainty about the impact of the Health Insurance Portability and Accountability Act (HIPAA). The project was revived in 2004 when a standard protocol was submitted to Institutional Review Boards (IRBs) in four different states.

RESULTS

All vital statistics departments reported that they were able to identify the decedent's name and demographic characteristics. Contact information for a relative or doctor was available in all states. Demographic characteristics and autopsy findings were available from 100% of the medical examiners offices. However, IRBs at the four institutions required major protocol modifications, including language and approach for contacting next of kin.

CONCLUSION

Availability of demographic and clinical data across states is consistent. The creation of a national fatal asthma registry appears feasible, but different IRB interpretations of what is permissible preclude a standard approach across states.

Fatal asthma in Finnish children and adolescents 1976-1998: validity of death certificates and a clinical description

Several studies show that asthma mortality in children and adolescents increased until the mid-1990s, after which it has slightly decreased worldwide. The objective of this study was to describe the mortality rates of childhood asthma in Finland, and to analyze patient characteristics to identify predisposing factors for fatal asthma exacerbation among children and adolescents during 1976-1998 (2004). All death certificates where asthma or related respiratory tract disease was coded as the underlying cause of death were reviewed for those under 20 years of age. Health care records and autopsy reports were evaluated to validate the cause of death and to identify any predisposing factors. In all, there had been 28 asthma deaths. The validity of the death certificates proved to be good as only 7% were misclassified. Death occurred either in the very young children or adolescents: the median age in the group of <12 years (n = 15) was 3.3 years while the median age in the group of >12 years (n = 13) was 18.1 years. The fatal exacerbations occurred mostly during summer and early autumn. Clinical triggers, recorded for 14/22 patients with available patient records, included respiratory infection, (12) use of ibuprofen despite known allergy (1), and exercise after visiting a horse stable (1). The severity of the disease was discernible in 21 patients: severe in 15, moderate in 5, and mild in 1 patient. Inhaled corticosteroids were not used as maintenance or periodic therapy in 12/22 patients, of whom 4 had died during the 1990s. In conclusion, asthma mortality in Finnish children and adolescents was rare and its incidence remained stable. The validity of the death certificate diagnoses proved to be good. Poor asthma management and non or undertreatment with inhaled corticosteroids were risk factors for fatal asthma.

A systematic review of the psychological risk factors associated with near fatal asthma or fatal asthma

Psychological factors such as anxiety, depressive disorders and/or personality disorders may predispose patients with asthma to near fatal asthma (NFA) or fatal asthma (FA). NFA is defined by an asthma exacerbation resulting in respiratory arrest requiring mechanical ventilation or a pCO(2) >or=45 mm Hg. Most studies have used the case-control study design. Several studies analyzing the effects of psychological factors on the risk of NFA or FA have shown conflicting results. We reviewed all of the literature found by the systematic search done of psychological factors on the risk NFA or FA. A MEDLINE search identified 423 articles between 1960 and March 2006. Seven case-controlled studies were identified following strict applications of the inclusion and exclusion criteria. Due to the significant heterogeneity in the measurement of the psychological factors, a summary statistic was not calculated. The trial characteristics were tabulated and qualitative trends were observed to explain the heterogeneity in the results of the studies. Recommendations on future studies in the field are outlined in detail. Following a systematic assessment of all published studies, we cannot conclude that psychological factors increase the risk of NFA and FA.

Abnormalities of the bronchial arteries in asthma

STUDY OBJECTIVES

The bronchial arteries supply systemic blood to the airways, tracheobronchial lymph nodes, and nerves. Their structure has not been studied in patients with asthma.

DESIGN

Case-control study of pathologic changes of bronchial arteries in asthma.

PARTICIPANTS AND METHODS

Postmortem lungs were examined from three case groups: (1) fatal asthma (n = 12), death due to asthma; (2) nonfatal asthma (n = 12), asthmatic and death due to nonrespiratory causes; and (3) nonasthmatic control subjects (n = 12), no history of asthma and death due to nonrespiratory causes. In bronchial arteries with outer diameters of 0.1 to 1.0 mm, the areas of lumen, intima, and media were measured and compared between case groups.

RESULTS

There were no significant differences in artery size (outer diameter) or in medial area between the three groups. In the two asthma groups, the intimal area was increased (p < 0.05), with a corresponding decrease in luminal area compared with the control group. There was a significant effect of gender, age, and smoking on intimal area. In the asthma cases, the area of bronchial artery intima was related to duration of asthma (p < 0.05), and this increase was associated with smooth muscle proliferation, reduplication, and calcification of the elastica, but not with inflammatory cell infiltration.

CONCLUSIONS

While the pathophysiologic significance of these changes is uncertain, the relation to duration of asthma, age, and smoking suggests a secondary response to chronic airway disease.

The Ontario Asthma Regional Variation Study: emergency department visit rates and the relation to hospitalization rates

BACKGROUND

Hospitalization rates for asthma vary more than threefold across regions of Ontario. It is not known whether this variation is primarily due to regional differences in the rate of emergency department (ED) visits or hospital admissions.

OBJECTIVE

To determine the variation in ED visit rates for asthma in Ontario, and the relation between ED visit rates and hospitalization rates.

DESIGN, SETTING, AND PATIENTS

We studied patients with an ED disposition diagnosis of asthma in a stratified sample of 16 hospitals (pediatric facilities, 13; adult facilities, 14) over a 1-year period. Pediatric patients were defined as those patients who were </= 19 years of age.

MEASUREMENTS

Direct age-standardized and sex-standardized ED visit and hospitalization rates, and the percentages of patients presenting to EDs and subsequently admitted to the hospital were calculated for each site. High/low ratios (ie, extremal quotients [EQ]), weighted coefficients of variation (CVs), and the systematic component of variation (SCV) were used to summarize the variation among hospitals.

RESULTS

The total number of ED visits for asthma at participating sites was 12,518 (7,825 children and 4,693 adults). A total of 847 children (10.8%) and 322 adults (6.9%) were admitted to the hospital. Age-standardized and sex-standardized ED visit rates ranged from 8.7 to 25.2 per 1,000 population for children (EQ, 2.9; CV, 30.9%; SCV, 173; p < 0.001) and 1.7 to 10.1 per 1,000 population for adults (EQ, 5.9; CV, 52.9; SCV, 445; p < 0.001). The proportion of pediatric and adult ED visits resulting in admission to the hospital varied significantly by site (p < 0.001) and was inversely related to ED visit rates in children (p < 0.001) but not in adults. ED visit rates were related to hospitalization rates in children (p = 0.042) and adults (p < 0.0001), but only accounted for 4% and 27%, respectively, of the variation in hospitalization rates.

CONCLUSION

Hospitalization rates for asthma in Ontario are primarily influenced by the variation in the percentage of ED visitors admitted to the hospital rather than the ED visit rate.

Women with asthma: a review of potential variables and preferred medical management

OBJECTIVES

To summarize the potential variables that contribute to the increased risk of asthma in women, outline therapeutic strategies that address these variables, and review current treatment recommendations for both pregnant and nonpregnant women with asthma.

DATA SOURCES

Literature searches (MEDLINE and cross-references) were performed using the keywords asthma and women in combination with the terms compliance, depression, emergency department, hormones, menstruation, mortality, National Asthma Education and Prevention Program, osteoporosis, pregnancy, prevalence, smoking, and treatment. Searches were limited to human studies with data published before 2005.

STUDY SELECTION

The author selected relevant articles for inclusion in this review.

RESULTS

Fluctuations in sex hormones, menstruation, pregnancy, obesity, depression, medication nonadherence, and smoking may contribute to increased asthma symptoms or severity in women. Asthma control may be improved if physicians address conditions and behaviors associated with asthma variability and severity in women. Notably, asthma must be managed aggressively in pregnant women, because uncontrolled asthma can lead to perinatal complications. Asthma treatment in women is optimized through patient and physician adherence to national guideline recommendations, including provision of patient education and asthma action plans.

CONCLUSIONS

Multiple variables throughout the female life cycle may influence asthma control. Successful asthma management requires an ongoing partnership between the patient and her physician to address physiologic (eg, sex hormones, pregnancy, obesity, depression) and nonphysiologic (eg, smoking, medication nonadherence) factors that may contribute to decreased asthma control.

Cost effectiveness of leukotriene modifiers in adults with asthma

Asthma is the most common chronic disorder in industrialised nations, with over 100 million people worldwide affected. Leukotrienes are chemical mediators released from mast cells, eosinophils and basophils. They cause bronchoconstriction, an increase in mucous secretions and activation of inflammatory cells. Leukotriene modifiers are a long-term controller medication used to treat asthma. They function by selectively competing for the leukotriene receptor sites, thereby blocking their action, or by inhibiting 5-lipoxygenase and thus preventing leukotriene formation. Both current US and Global Initiative for Asthma treatment guidelines have clarified the role of leukotriene modifiers in the management of asthma in adults and children. Leukotriene modifiers have two distinct roles: to replace inhaled corticosteroids in milder asthma and as an add-on therapy to inhaled corticosteroids in more severe asthma. While efficacy is certainly an important issue, economic considerations are also important in a disease such as asthma where there are a variety of treatment options and the severity of the disease varies widely. This review examined published studies to better understand the cost effectiveness of leukotriene modifiers in adults with asthma. Fifteen articles were found that analysed the cost effectiveness of leukotriene modifiers, with almost all performed in the US. The vast majority of the studies were retrospective claims analyses, but three randomised controlled trials incorporating economic outcomes have been reported. The majority of the articles found that for both monotherapy in mild persistent asthma and add-on therapy in moderate persistent asthma, leukotriene modifiers were less cost effective than inhaled corticosteroids with or without a long-acting beta2-adrenoceptor agonist. However, these results must be viewed cautiously as in several studies there were methodological issues such as comparisons of unequal treatment groups or inappropriate use of leukotriene modifiers in stepwise treatment.

Asthma mortality, inhaled steroids, and changing asthma therapy in Argentina (1990-1999)

BACKGROUND

The asthma managing strategy has evolved and inhaled corticosteroids (ICS) are now the cornerstone of asthma treatment. Their effect on symptoms and exacerbations are well ascertained, whereas their effects on asthma mortality are still matter of debate. This ecological study evaluated asthma mortality rates and drug sales in the decade 1990-1999 in Argentina.

METHODS

Mortality (overall and adjusted for 5-34 years) was obtained from the Argentinean Epidemiological Institute, and data on the sales of antiasthma drugs were provided by the International Marketing Survey.

RESULTS

There was a significant change in drug sales in the spanned period: ICS +479%, inhaled beta2 agonists +32%, theophylline -63%. The crude and adjusted mortality rates were 3.38 and 0.72 in the 1980-1989 decade, and 2.58 (P<0.05) and 0.38 (P<0.01) in the subsequent one. There was inverse correlation between inhaled corticosteroid sale and age-adjusted (5-34) asthma mortality (r=-0.84; P=0.003), and the same with global mortality rates (r=-0.81; P=0.005). A positive correlation was also seen between theophylline sales and mortality.

CONCLUSION

The increased sale of ICS and possibly the decrease of theophylline use seem to be the more relevant factors associated with decreased asthma mortality in Argentina.

Fractal geometry of airway remodeling in human asthma

RATIONALE

Airway wall remodeling is an important aspect of asthma. It has proven difficult to assess quantitatively as it involves changes in several components of the airway wall.

OBJECTIVE

To develop a simple method for quantifying the overall severity of airway wall remodeling in asthmatic airways using fractal geometry.

METHODS

Negative-pressure silicone rubber casts of lungs were made using autopsy material from three groups: fatal asthma, nonfatal asthma, and nonasthma control. All subjects were lifelong nonsmokers. A fractal dimension was calculated on two-dimensional digital images of each cast.

RESULTS

Nonasthma control casts had smooth walls and dichotomous branching patterns with nontapering segments. Asthmatic casts showed many abnormalities, including airway truncation from mucous plugs, longitudinal ridges, and horizontal corrugations corresponding to elastic bundles and smooth muscle hypertrophy, respectively, and surface projections associated with ectatic mucous gland ducts. Fractal dimensions were calculated from digitized images using an information method. The average fractal dimensions of the airways of both the fatal asthma (1.72) and nonfatal asthma (1.76) groups were significantly (p<0.01 and p=0.032, respectively) lower than that of the nonasthma control group (1.83). The lower fractal dimension of asthmatic airways correlated with a decreased overall structural complexity and pathologic severity of disease.

CONCLUSION

Fractal analysis is a simple and useful technique for quantifying the chronic structural changes of airway remodeling in asthma.

Is mild asthma really 'mild'?

Current evidence suggests that patients with mild asthma are often under-recognised, and those that are diagnosed can remain with this initial classification and be treated accordingly, despite worsening of their condition. There is considerable overlap between mild and more severe asthma in terms of the underlying pathophysiology and poorly reversible airway changes, such as subepithelial fibrosis and airway wall remodelling, which are present very early in the progression of asthma in patients with normal lung function. Life-threatening exacerbations can also occur in patients with mild asthma. In view of these factors and given that asthma is a two-component disease (airway inflammation and smooth muscle dysfunction), recent studies have examined the effects of both early intervention with steroids and combination therapy comprising an inhaled steroid and a long acting beta(2)-agonist. These studies suggest that early intervention is likely to provide better asthma control and possibly prevent or delay the worsening of disease and fatalities in patients considered to be mild asthmatics.

Continuing decreases in asthma mortality in the United States

BACKGROUND

Rates of death from asthma in the United States increased after 1978 until 1988 and then tended to stabilize through 1997.

OBJECTIVE

To identify and evaluate subsequent trends in asthma mortality in the United States.

METHODS

Tabulation and graphing of data from the National Center for Health Statistics identifying asthma (International Classification of Diseases [ICD], Ninth Revision, code, 493; ICD-10 code, J45-J46) as the underlying cause of death in the 50 United States and the District of Columbia with rates of death from asthma by age, race, and sex and age-adjusted rates of death by race.

RESULTS

Rates of death from asthma in the United States increased from 0.8 per 100,000 general population in 1977 and 1978 to 2.0 in 1989 and 2.1 in 1994 through 1996 but have decreased to 1.6 in 2000, a decrease accounted for only partly by implementation in 1999 of the ICD-10. Rates have been higher for women than men but have decreased for both. Age-adjusted rates of death for asthma have been much higher for blacks than whites.

CONCLUSION

Asthma mortality has stabilized since 1988 and decreased since 1998. Improved management and recent decreases in prevalence are the most likely explanations for these recent trends.

Acute asthma in adults: a review

All patients with asthma are at risk of having exacerbations. Hospitalizations and emergency department (ED) visits account for a large proportion of the health-care cost burden of asthma, and avoidance or proper management of acute asthma (AA) episodes represent an area with the potential for large reductions in health-care costs. The severity of exacerbations may range from mild to life threatening, and mortality is most often associated with failure to appreciate the severity of the exacerbation, resulting in inadequate emergency treatment and delay in referring to hospital. This review describes the epidemiology, costs, pathophysiology, mortality, and management of adult AA in the ED and in the ICU.

Food allergy as a risk factor for life-threatening asthma in childhood: a case-controlled study

BACKGROUND

No objective clinical risk factors exist for pediatric life-threatening asthma.

OBJECTIVES

In this study, we address whether persistent food allergy and degree of atopy are risk factors for life-threatening asthma.

METHODS

By use of a case-controlled design, children (1-16 years) ventilated for an exacerbation of asthma were enrolled. Each case was matched by sex, age, and ethnicity, with 2 controls who had attended with a non-life-threatening exacerbation. All subjects were assessed by means of a questionnaire, spirometry, and skin prick or RAST testing. The data were analyzed by conditional logistic regression.

RESULTS

Nineteen cases and 38 controls were enrolled. Compared with controls, cases were found to have the following risk factors: food allergy (odds ratio, 8.58; 95% CI, 1.85-39.71), multiple allergic diagnoses (4.42; 1.17-16.71), early onset of asthma (6.48; 1.36-30.85), and frequent admissions (14.2; 1.77-113.59). After regression analysis, only frequent admission with asthma (9.85; 1.04-93.27) and food allergy (5.89; 1.06-32.61) were independently associated with life-threatening asthma. Half the cases had food allergy compared with only 10% of controls.

CONCLUSION

This study demonstrates that poorly controlled asthma and food allergy are significant risk factors for life-threatening asthma. More intensive management of this high-risk group of children might help to reduce future morbidity and mortality.

6. Asthma

The increasing incidence and prevalence of asthma in many parts of the world continue to make it a global health concern. The heterogeneous nature of the clinical manifestations and therapeutic responses of asthma in both adult and pediatric patients indicate that it may be more of a syndrome rather than a specific disease entity. Numerous triggering factors including viral infections, allergen and irritant exposure, and exercise, among others, complicate both the acute and chronic treatment of asthma. Therapeutic intervention has focused on the appreciation that airway obstruction in asthma is composed of both bronchial smooth muscle spasm and variable degrees of airway inflammation characterized by edema, mucus secretion, and the influx of a variety of inflammatory cells. The presence of only partial reversibility of airflow obstruction in some patients indicates that structural remodeling of the airways may also occur over time. Choosing appropriate medications depends on the disease severity (intermittent, mild persistent, moderate persistent, severe persistent), extent of reversibility, both acutely and chronically, patterns of disease activity (exacerbations related to viruses, allergens, exercise, etc), and the age of onset (infancy, childhood, adulthood).

Rate and place of death from asthma among different ethnic groups in Israel: national trends 1980 to 1997

STUDY OBJECTIVES

To compare the trends of asthma mortality and place of death in young patients (ages 5 to 34 years) from different major population groups in Israel.

DESIGN

Retrospective study.

PATIENTS AND PARTICIPANTS

Patients who died from asthma between the years 1980 and 1997 according to the death record of the National Israeli Health Registry.

RESULTS

During the period studied, 100 asthma mortality cases were reported, which yields a mean mortality rate of 0.226 per 100,000 population. There were no significant changes in the mortality rates over the years. The mean (+/- SD) age of death was 23 +/- 7 years. Of this population, 84.5% were Jews and 15.5% were Arabs, which is proportionate to the general Israeli population. In 52% of the cases, the patients died outside a hospital. There was no significant difference in the place of death between Jews and Arabs. Significantly more men (62.5%) than women (40%) died outside the hospital (p = 0.025).

CONCLUSIONS

The asthma mortality rate in Israel during the years 1980 to 1997 was low and stable. Most of the patients still died outside the hospital. There was no difference in the asthma death rate and place of death between Jews and Arabs, suggesting that in our population genetic predisposition is not likely to be a risk factor for mortality.

Reducing disparities in asthma care: priorities for research--National Heart, Lung, and Blood Institute workshop report

Minority groups with diverse racial and ethnic heritages and persons living in poverty are much more likely to die of asthma and to require emergency care for exacerbations of asthma than white persons not living in poverty. The National Heart, Lung, and Blood Institute convened a multidisciplinary group of expert scientists and clinicians to review current research aimed at understanding risk factors for these disparities in asthma health outcomes, to describe key barriers to improving asthma outcomes, and to establish priorities for future research. Education programs for asthma and other chronic diseases were reviewed. Successful elements of clinic and community-based programs were identified. Factors potentially involved in producing disparities include gene-environment interaction, psychologic and social factors, and socioeconomic status. Stress potentially contributes to asthma morbidity at both the individual and community level. Recommendations are made to stimulate research to understand risk factors for disparities and their mechanisms (e.g., gene-by-environment interactions and the role of stress), to define appropriate research designs and methods for evaluating behavioral and community interventions, and to examine how differential access to care contributes to morbidity. Research is encouraged to identify strategies that improve cultural adaptation and adoption of proven programs in a variety of populations.

Contemporary approach to the emergency department management of pediatric asthma

Asthma continues to be an enormous health problem and economic burden in US society. EDs probably will continue to provide a substantial amount of care for those affected by the disease. Pediatric asthma patients frequently are encountered in EDs. Emergency physicians must remain current in their approach to providing expert care while the management of acute asthma exacerbations continues to evolve, older therapies are challenged and new therapies are developed, tested, and implemented.

Covert fears and anxiety in asthma and congenital heart disease

AIM

To compare anxiety, fears and behavioural problems in children with asthma and children with congenital heart disease, and with the normative population. To also review the influence of maternal anxiety, time since diagnosis and severity of disease.

DESIGN

Children administered Fear Survey Scale (FSSC-R) and Child Manifest Anxiety Scale (R-CMAS). Mothers given Child Behaviour Checklist (CBCL) and State Trait Anxiety Scale (STAI-S and STAI-T). Normative means and SDs compared with means and SDs for both medical groups. The mother's scores on the STAI-S and STAI-T scales were correlated with the child's scores on the FSSC-R and the R-CMAS.

SETTING

Outpatient Asthma and Cardiology multidisciplinary Clinics at a tertiary care paediatric facility, Alberta Children's Hospital.

SUBJECTS

Forty children with asthma (aged 6--17 years) were compared with 39 children with congenital heart disease. Intake questionnaires and interviews determined these children to be without obvious psycho-social problems.

RESULTS

Children with asthma and children with congenital heart disease had more medical fears, and more physiological anxiety than normative samples. Increased maternal anxiety was correlated in both groups with increased child anxiety, medical fears and behavioural problems in the child. Similarly, increased severity of asthma or cardiac problems was associated with more physiological anxiety and more fears. Less time since diagnosis of the disease adversely affected social interactions in both groups of children.

CONCLUSION

Physiological anxiety, medical fears and maternal anxiety are important issues requiring attention in asthma and cardiac disease, even in the absence of obvious psychosocial problems. There may be specific problems with a recent diagnosis of a chronic illness.

Inhaled corticosteroids: impact on asthma morbidity and mortality

Inhaled corticosteroids are now recommended as first-line therapy for asthma. Although these drugs clearly improve the symptoms of the disease and the associated physiologic abnormalities, epidemiologic studies provide important information on their effectiveness in preventing asthma morbidity and mortality. We review the evidence regarding the role of inhaled corticosteroids in the prevention of asthma fatality and hospitalization. In the process, we discuss the methodologic complexities of the nonexperimental studies and the implications of the methodologic issues on the evaluation of the impact of these drugs. Eight of the cohort and ecologic studies conducted to date strongly suggest that inhaled corticosteroids, when taken regularly, decrease the number of hospitalizations for asthma by up to 80%. For asthma death, the results of 11 investigations appear less consistent, especially those of several cohort and case-control studies whose principal objective was to examine not the benefit of inhaled corticosteroids but the adverse effects of other drug classes. Much of the inconsistency in the results, however, can be explained by weaknesses in study design and analysis-in particular, the failure to consider exposure in terms of regular use of inhaled corticosteroids. When the most recent study involving the use of the Saskatchewan databases is considered, it is evident that regular treatment with conventional or low-dose inhaled cortico-steroids results in a significant reduction in fatalities due to asthma. In all, the evidence to date strongly indicates that regular use of inhaled corticosteroids, even at low doses, would prevent the major portion of asthma hospitalizations and deaths.

Decreases in asthma mortality in the United States

BACKGROUND

Rates of death from asthma in the United States increased from 1978 until 1988 and have tended to stabilize since then.

OBJECTIVE

To identify and evaluate recent trends in asthma mortality in the United States.

METHODS

Graphing and tabulation of data from the National Center for Health Statistics identifying asthma (ICD 493) as the underlying cause of death in the 50 United States and the District of Columbia with rates of death from asthma by age, race, and sex and age-adjusted rates of death by race.

RESULTS

Rates of death from asthma in the United States increased from 0.8 per 100,000 general population in 1977 and 1978 to 2.0 in 1989 and 2.1 in 1994 through 1996 but decreased to 2.0 in 1997. Rates decreased for black females and males and for white females in 1997. Age-adjusted rates of death from asthma decreased in 1997 for both blacks and whites. Deaths from asthma in children less than 15 years of age decreased from 191 in 1996 to 154 in 1997, the greatest decrease in any single year since 1971.

CONCLUSION

Decreases in deaths from asthma in the United States in 1997 have followed stabilization of asthma mortality rates since 1988, although changes in a single year cannot establish a trend. Improved management is the most likely explanation of reversal of previous increases in asthma mortality.