Risk factors for asthma deaths: a population-based, case-control study

Real-life impact of uncontrolled severe asthma on mortality and healthcare use in adolescents and adults: findings from the retrospective, observational RESONANCE study in France

OBJECTIVE

To characterise uncontrolled severe asthma and compare the disease burden with the general and asthmatic populations.

DESIGN

Retrospective observational study using a national sample of a French healthcare database (Echantillon Généraliste des Bénéficiaires (EGB)).

SETTING

The EGB, an anonymised permanent sample of health insurance databases, representing 1/97th of the French population.

PARTICIPANTS

Patients (≥12 years) were selected in year 2014 and followed 2 years. A cohort of patients with uncontrolled severe asthma was defined using an algorithm based on peer-reviewed literature and Global Initiative for Asthma recommendations. Index date was the occurrence of the first marker of uncontrolled asthma. This cohort was matched with two control cohorts, general population and asthmatic controls, on baseline characteristics.

MAIN OUTCOMES MEASURES

Mortality, healthcare use and associated costs were studied in the 2 years of follow-up.

RESULTS

Among 467 716 individuals in the EGB, 16 588 patients with asthma were identified, including 739 (4.5%) with uncontrolled severe disease. The survival probability at 2 years for patients with uncontrolled severe asthma (92.0%) was lower than in the general population cohort (96.6%; relative risk of death: 2.35; 95% CI: 1.70 to 3.29; p<0.0001) and tended to be lower than in the control asthmatic cohort (94.3%; p=0.07). Emergency department visits and hospitalisations were higher in patients with uncontrolled severe asthma than in the general population (64.7% vs 34.9%; p<0.0001) and asthmatic controls (64.7% vs 55.2%; p=0.0002). Other components of healthcare use (medical and paramedical visits, medications) were increased in patients with uncontrolled severe asthma compared with control populations. These increases translated into higher costs (p<0.0001 for both comparisons).

CONCLUSIONS

This study demonstrates the huge burden of uncontrolled severe asthma in terms of mortality, morbidity and healthcare resource consumption compared with other patients with asthma and with the general population and emphasises the importance of appropriate management in this high-risk population.

Medical Neglect as a Contributor to Poorly Controlled Asthma in Childhood

Child maltreatment, including medical neglect, is a frequent contributor to the development of asthma as well as a barrier to its proper management. This article aims to review the role of medical neglect as a contributor to poor asthma control. Medical neglect can present as failure of the caretaker to recognize severe asthma symptoms in a child, non-adherence to medical management, failure to prevent chronic exposure to allergens or tobacco smoke, poor child nutrition leading to obesity, and allowing a young child to manage his/her illness without supervision. This article will explore the different factors leading to medical neglect (as illustrated by two cases) and suggest possible interventions aiming to prevent emergency department visits, hospitalizations, and asthma-related deaths.

Chronic rhinosinusitis disease burden is associated with asthma-related emergency department usage

PURPOSE

Chronic rhinosinusitis (CRS) disease burden is associated with pulmonary status in asthmatic CRS patients. Asthma-related emergency department (ED) usage is a predictor of asthma-related mortality. We sought to determine whether measures of CRS disease burden are associated with asthma-related ED usage.

METHODS

We prospectively recruited 263 asthmatic CRS patients for this cross-sectional study. CRS burden was measured using the 22-item Sinonasal Outcome Test (SNOT-22), and patient-reported CRS-related antibiotic usage and CRS-related oral corticosteroids usage over the preceding year. Asthma-related ED visits over the prior year were also assessed.

RESULTS

Of all participants, 18.6% had at least 1 asthma-related ED visit (mean 0.3 ED visits for the whole cohort). Asthma-related ED usage was associated with SNOT-22 score [adjusted rate ratio (RR) = 1.02, 95% CI 1.01-1.03, p = 0.040] and CRS-related oral corticosteroids usage in the past year (RR = 1.52, 95% CI 1.26-1.83, p < 0.001). From the SNOT-22 score, asthma-related ED usage was only associated with the nasal subdomain score (RR = 1.08, 95% CI 1.03-1.13, p = 0.001). These measures of CRS disease burden could be used with good sensitivity and specificity to detect patients with asthma-related ED usage in the past year, the majority of whom were undertreated for their asthma.

CONCLUSIONS

Measures of CRS disease burden are associated with and can be used to detect, patients having asthma-related ED usage. These results further solidify the connection between CRS and asthma disease courses, and also present an opportunity to use CRS disease burden as a tool for identifying-and implementing greater treatment of-patients at highest risk for asthma-related mortality.

Prognostic nomogram for inpatients with asthma exacerbation

Background

Asthma exacerbation may require a visit to the emergency room as well as hospitalization and can occasionally be fatal. However, there is limited information about the prognostic factors for asthma exacerbation requiring hospitalization, and no methods are available to predict an inpatient’s prognosis. We investigated the clinical features and factors affecting in-hospital mortality of patients with asthma exacerbation and generated a nomogram to predict in-hospital death using a national inpatient database in Japan.

Methods

We retrospectively collected data concerning hospitalization of adult patients with asthma exacerbation between July 2010 and March 2013 using the Japanese Diagnosis Procedure Combination database. We recorded patient characteristics and performed Cox proportional hazards regression analysis to assess the factors associated with all-cause in-hospital mortality. Then, we constructed a nomogram to predict in-hospital death.

Results

A total of 19,684 patients with asthma exacerbation were identified; their mean age was 58.8 years (standard deviation, 19.7 years) and median length of hospital stay was 8 days (interquartile range, 5–12 days). Among study patients, 118 died in the hospital (0.6%). Factors associated with higher in-hospital mortality included older age, male sex, reduced level of consciousness, pneumonia, and heart failure. A nomogram was generated to predict the in-hospital death based on the existence of seven variables at admission. The nomogram allowed us to estimate the probability of in-hospital death, and the calibration plot based on these results was well fitted to predict the in-hospital prognosis.

Conclusion

Our nomogram allows physicians to predict individual risk of in-hospital death in patients with asthma exacerbation.

Frequency of health service use in the year prior to asthma death

OBJECTIVE

High frequency health service use (HSU) is associated with poorly controlled asthma, and is a recognized risk factor for near-fatal or fatal asthma. The objective of this study was to describe the frequency of HSU in the year prior to asthma death.

METHODS

Individuals aged 0-99 years who died from asthma from April 1996 to December 2011 in Ontario, Canada were identified as cases. Cases were matched to 4-5 live asthma controls by age, sex, rural/urban residence, socioeconomic status, duration of asthma and a co-diagnosis of COPD. HSU records in the year prior to death [hospitalization, emergency department (ED) and outpatient visits] were assembled. The association of prior HSU and asthma death was measured by conditional logistic regression models.

RESULTS

From 1996 to 2011, 1503 individuals died from asthma. While the majority of cases did not have increased HSU as defined in the study, compared to matched live asthma controls, the cases were 8-fold more likely to have been hospitalized two or more times (OR = 7.60; 95% CI: 4.90, 11.77), 13-fold more likely to have had three or more ED visits (OR = 13.28; 95% CI: 7.55, 23.34) and 4-fold more likely to have had five or more physician visits for asthma (OR = 4.41; 95% CI: 3.58, 5.42).

CONCLUSIONS

Frequency of HSU in the year prior was substantially higher in those died from asthma. Specifically, more than one asthma hospital admission, three ED visits or five physician visits increased the asthma mortality risk substantially and exponentially.

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.

Asthma mortality in Serbia: a 30-year analysis

INTRODUCTION

The asthma mortality pattern differs among countries. No published evidence is currently available on asthma mortality in a European low-middle-income country in socioeconomic transition. We analyzed the trend of asthma mortality rate in Serbia during the period 1980-2009.

MATERIALS AND METHODOLOGY

a descriptive study; source of data: Republic of Serbia Institute of Statistics Death Registry. We analyzed asthma mortality data in the total population, including gender specific analysis, and in the selected ≥ 5-34 year age group. The International Classification of Diseases codes for asthma 493 (1980-1996) and J45 + J46 (1997-2009) were included. Population estimates were based on 1991 and 2002 census data, with extrapolation.

RESULTS

The over-all average mortality rate was 7.27 ± 2.14/100,000 inhabitants. The mortality rate peaked in 1981 at 11.3/100,000 but was 4.45/100,000 in the last year of analysis. While both overall mortality rate, as well as gender specific rates, showed clear decreases over the observed 30-year period (average absolute annual decrease of 0.195/100,000 inhabitants, 0.241/100,000 men and 0.149/100,000 women; p < 0.001) with corresponding relative annual decreases of 2.9% for the whole population, 3.0% for men and 2.8% for women, a stable trend of the rate was found in the age group ≥ 5-34 years. Male-to-female ratio was 1.59 ± 0.186, on average and it showed a stable trend over the observed period.

CONCLUSION

Although the failure of the health care system during the socioeconomic crisis of the 1990s might have transiently affected asthma mortality rates, the overall mortality rate for the disease shows a favorable decreasing trend.

Refractory asthma in the UK: cross-sectional findings from a UK multicentre registry

INTRODUCTION

Refractory asthma represents a significant unmet clinical need where the evidence base for the assessment and therapeutic management is limited. The British Thoracic Society (BTS) Difficult Asthma Network has established an online National Registry to standardise specialist UK difficult asthma services and to facilitate research into the assessment and clinical management of difficult asthma.

METHODS

Data from 382 well characterised patients, who fulfilled the American Thoracic Society definition for refractory asthma attending four specialist UK centres--Royal Brompton Hospital, London, Glenfield Hospital, Leicester, University Hospital of South Manchester and Belfast City Hospital--were used to compare patient demographics, disease characteristics and healthcare utilisation.

RESULTS

Many demographic variables including gender, ethnicity and smoking prevalence were similar in UK centres and consistent with other published cohorts of refractory asthma. However, multiple demographic factors such as employment, family history, atopy prevalence, lung function, rates of hospital admission/unscheduled healthcare visits and medication usage were different from published data and significantly different between UK centres. General linear modelling with unscheduled healthcare visits, rescue oral steroids and hospital admissions as dependent variables all identified a significant association with clinical centre; different associations were identified when centre was not included as a factor.

CONCLUSION

Whilst there are similarities in UK patients with refractory asthma consistent with other comparable published cohorts, there are also differences, which may reflect different patient populations. These differences in important population characteristics were also identified within different UK specialist centres. Pooling multicentre data on subjects with refractory asthma may miss important differences and potentially confound attempts to phenotype this population.

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.

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.

Asthma fatalities at the Emergency Department of the Singapore General Hospital

BACKGROUND

Bronchial asthma is one of the most common chronic diseases in Singapore and the prevalence is increasing. Despite this, the worldwide mortality rate from asthma has been noted to be low at an average of 2.0 per 100,000 people in developed countries such as the United States. Risk factors for fatal asthma attacks that have been described include excessive use of short acting beta-agonists, errors in clinical judgement, poor compliance, psychosocial disorders, use of three or more groups of asthma medication and indicators of asthma severity.

AIM

We aim to study the incidence of asthma deaths occurring in the emergency department of a tertiary care hospital in Singapore.

METHODS

Of the total number of patients at the Department of Emergency Medicine in Singapore General Hospital from January 1999 to June 2005, eight fatalities were attributed to exacerbation of bronchial asthma. The characteristics of these patients are described.

RESULTS

A low incidence of asthma-related deaths is found in Singapore.

The economic value of anti-IgE in severe persistent, IgE-mediated (allergic) asthma patients: adaptation of INNOVATE to Sweden

BACKGROUND

Severe allergic asthma patients may not be controlled even with guideline recommended care, including inhaled corticosteroids, long-acting beta-2 agonists, theophylline, oral steroids and anti-leukotrienes. They experience exacerbations requiring intensive healthcare use and which may be fatal. Omalizumab, a new monoclonal antibody for use in IgE-mediated allergic diseases, reduces exacerbations and daily symptoms in this patient population. The aim of this study is to estimate the cost effectiveness of adding omalizumab to optimized standard therapy (ST) in patients with severe persistent IgE-mediated (allergic) asthma.

METHODS

A Markov model comparing lifelong ST with a treatment period of omalizumab add-on therapy followed by ST, was developed based on efficacy data from the INNOVATE trial (28 weeks, N = 419) and Swedish life table and cost data. This model assumes that patients are at risk of having an exacerbation every 2 weeks and are at risk of dying from a clinically significant severe asthma exacerbation. Patients in a steady-state of having no exacerbations are defined to be in an 'optimized asthma control' state. Resource use data and utilities were obtained from INNOVATE and from a UK observational study. Costs from a societal perspective include estimates for drugs, routine care, exacerbations and costs in added years of life; benefits are expressed in QALYs. The response to omalizumab was evaluated after 16 weeks of trial, and non-responders stopped taking omalizumab for the remaining time.

RESULTS

Total lifetime discounted costs and QALYs on ST were 52,702 euros and 11.60. Omalizumab add-on therapy cost an additional 42,754 euros for 0.76 additional QALYs, resulting in an incremental cost-effectiveness ratio of 56,091 euros. A probabilistic sensitivity analysis indicates that the 95% CI around the ICER is [31,328 euros; 120,552 euros]. One-way analyses indicate that the results are sensitive to the exacerbation-related mortality rate, the time horizon and the discount rates.

CONCLUSIONS

Based on the model and the assumptions used, our results suggest that omalizumab provides cost offsets, improves quality of life and may have an attractive ICER in treating the severe allergic asthma population.

A multiple cause-of-death analysis of asthma mortality in the United States, 1990-2001

OBJECTIVES

Most analyses of asthma mortality in the United States have relied solely on underlying cause-of-death data, which may underestimate the magnitude of asthma-related mortality. We used multiple cause-of-death data to examine asthma-related mortality trends in the United States.

METHODS

Data were selected from the United States Multiple Cause-of-Death Files, 1990-2001. Mortality rates and 95% confidence intervals were computed to examine differences in asthma mortality over time and by age, race/ethnicity, and gender. Location of death and seasonal variations in asthma mortality were also assessed, as well as the impact of seasonal respiratory infections.

RESULTS

We identified 135,668 asthma-related deaths in the United States over the 12-year period, representing an age-adjusted mortality rate of 4.4 per 100,000. Only 45% of the asthma-related deaths had asthma recorded as the underlying cause. Whites and older adults were less likely to have asthma listed as the underlying cause. Asthma mortality rates mirrored underlying cause trends, increasing slightly between 1990 and 1995, declining between 1996 and 1998, and further declining after International Classification of Disease (ICD)-10 implementation in 1999. Mortality was highest among blacks and the elderly and was higher among females than males. Asthma-related deaths peaked in the winter months and were over four times more likely than non-asthma deaths to have acute upper respiratory infections, influenza, or acute bronchitis listed on the death record. The proportion of asthma-related deaths occurring outside a medical setting increased steadily over the period, from 23.3% in 1990 to 29.4% in 2001.

CONCLUSIONS

The burden of asthma may be underestimated by relying solely on underlying cause-of-death data. Further research is needed to determine the reasons for the steady increase in out-of-hospital deaths and the continued demographic disparities in mortality.

Clinical practice guidelines: medical follow-up of patients with asthma--adults and adolescents

The follow-up of patients with asthma should focus on asthma control (disease course over a number of weeks).

Deaths certified as asthma and use of medical services: a national case-control study

BACKGROUND

Studies have linked asthma death to either increased or decreased use of medical services.

METHODS

A population based case-control study of asthma deaths in 1994-8 was performed in 22 English, six Scottish, and five Welsh health authorities/boards. All 681 subjects who died were under the age of 65 years with asthma in Part I on the death certificates. After exclusions, 532 hospital controls were matched to 532 cases for age, district, and date of asthma admission/death. Data were extracted blind from primary care records.

RESULTS

The median age of the subjects who died was 53 years; 60% of cases and 64% of controls were female. There was little difference in outpatient attendance (55% and 55%), hospital admission for asthma (51% and 54%), and median inpatient days (20 days and 15 days) in the previous 5 years. After mutual adjustment and adjustment for sex, using conditional logistic regression, three variables were independently associated with asthma death: fewer general practice contacts (odds ratio 0.82 (95% confidence interval (CI) 0.74 to 0.91) per 5 contacts) in the previous year, more home visits (1.14 (95% CI 1.08 to 1.21) per visit) in the previous year, and fewer peak expiratory flow recordings (0.83 (95% CI 0.74 to 0.92) per occasion) in the previous 3 months. These associations were similar after adjustment for markers of severity, psychosocial factors, systemic steroids, short acting bronchodilators and antibiotics, although the association with peak flow was weakened and just lost significance.

CONCLUSION

Asthma death is associated with less use of primary care services. Both practice and patient factors may be involved and a better understanding of these may offer possibilities for reducing asthma death.

Benefits of omalizumab as add-on therapy in patients with severe persistent asthma who are inadequately controlled despite best available therapy (GINA 2002 step 4 treatment): INNOVATE

BACKGROUND

Patients with severe persistent asthma who are inadequately controlled despite Global Initiative for Asthma (GINA) 2002 step 4 therapy are a challenging population with significant unmet medical need. We determined the effect of omalizumab on clinically significant asthma exacerbations (requiring systemic corticosteroids) in the first omalizumab study to exclusively enrol patients from this difficult-to-treat patient population.

METHODS

Following a run-in phase, patients (12-75 years) inadequately controlled despite therapy with high-dose inhaled corticosteroids (ICS) and long-acting beta(2)-agonists (LABA) with reduced lung function and a recent history of clinically significant exacerbations were randomized to receive omalizumab or placebo for 28 weeks in a double-blind, parallel-group, multicentre study.

RESULTS

A total of 419 patients were included in the efficacy analyses. The clinically significant asthma exacerbation rate (primary efficacy variable), adjusted for an observed relevant imbalance in history of clinically significant asthma exacerbations, was 0.68 with omalizumab and 0.91 with placebo (26% reduction) during the 28-week treatment phase (P = 0.042). Without adjustment, a similar magnitude of effect was seen (19% reduction), but this did not reach statistical significance. Omalizumab significantly reduced severe asthma exacerbation rate (0.24 vs 0.48, P = 0.002) and emergency visit rate (0.24 vs 0.43, P = 0.038). Omalizumab significantly improved asthma-related quality of life, morning peak expiratory flow and asthma symptom scores. The incidence of adverse events was similar between treatment groups.

CONCLUSIONS

In patients with inadequately controlled severe persistent asthma, despite high-dose ICS and LABA therapy, and often additional therapy, omalizumab significantly reduced the rate of clinically significant asthma exacerbations, severe exacerbations and emergency visits. Omalizumab is effective and should be considered as add-on therapy for patients with inadequately controlled severe persistent asthma who have a significant unmet need despite best available therapy.

The effect of treatment with omalizumab, an anti-IgE antibody, on asthma exacerbations and emergency medical visits in patients with severe persistent asthma

BACKGROUND

Patients with severe persistent asthma who are inadequately controlled despite treatment according to current asthma management guidelines have a significant unmet medical need. Such patients are at high risk of serious exacerbations and asthma-related mortality.

METHODS

Here, we pooled data from seven studies to determine the effect of omalizumab, an anti-immunoglobulin E (IgE) monoclonal antibody, on asthma exacerbations in patients with severe persistent asthma. Omalizumab was added to current asthma therapy and compared with placebo (in five double-blind studies) or with current asthma therapy alone (in two open-label studies). The studies included 4308 patients (2511 treated with omalizumab), 93% of whom had severe persistent asthma according to the Global Initiative for Asthma (GINA) 2002 classification. Using the Poisson regression model, results were calculated as the ratio of treatment effect (omalizumab : control) on the standardized exacerbation rate per year.

RESULTS

Omalizumab significantly reduced the rate of asthma exacerbations by 38% (P < 0.0001 vs control) and the rate of total emergency visits by 47% (P < 0.0001 vs control). Analysis of demographic subgroups showed that the efficacy of omalizumab on asthma exacerbations was unaffected by patient age, gender, baseline serum IgE (split by median) or by 2- or 4-weekly dosing schedule, although benefit in absolute terms appeared to be greatest in patients with more severe asthma, defined by a lower value of percentage predicted forced expiratory volume in 1 s (FEV(1)) at baseline.

CONCLUSIONS

These results suggest that omalizumab may fulfil an important need in patients with severe persistent asthma, many of whom are not adequately controlled on current therapy.

[Severe asthma in the general population: definition and prevalence]

RATIONALE

Severe asthma is a real public health problem because of its consequences on patients and its economic cost. Nevertheless, few epidemiological studies have focussed on severe asthma. The aim of this state of the art review is to describe the criteria used to estimate asthma severity and to assess the prevalence of severe asthma from population-based epidemiological studies.

OBSERVATIONS

Asthma severity has been defined in various ways in epidemiology, with criteria based on symptoms, hospitalisation, ventilatory function, discomfort caused by asthma attacks, and treatment. A high variability in the prevalence of severe asthma is observed, resulting mostly from the lack of standardisation in the phenotypes used, but also from a real geographical heterogeneity. Nevertheless, the prevalence of severe asthma may be reasonably estimated between 1 and 3% of the general population, both in children and adults.

CONCLUSION

Data from the literature show a lack of standardisation of the severe asthma phenotype. Further epidemiological studies are needed to understand the geographical variability in severe asthma prevalence.

Risk factors for an intensive care unit admission in children with asthma

An admission to an intensive care unit (ICU) with asthma is a marker of asthma severity and may be a precursor of asthma death. The aim of this study was to investigate risk factors for acute severe asthma needing an ICU admission. We hypothesized that children admitted to the ICU represent a severe phenotype with identifiable premorbid clinical features. The study was case-control in design. One hundred and forty-one children were studied. Seventy children admitted to the ICU and 71 children admitted to the general medical ward served as cases and controls, respectively. Children were aged between 1-16 years. They underwent skin prick allergy testing, and had a nasopharyngeal aspirate and serology performed to screen for respiratory pathogens. Their parents completed an asthma and allergy symptom questionnaire and the Newcastle Asthma Knowledge Questionnaire (NAKQ). On univariate analysis, an admission to the ICU was more likely in children with 1) "frequent episodic" or "persistent" background asthma; 2) three or more previous admissions for asthma; 3) one or more asthma admissions in the previous 12 months; 4) three or more presentations to the Emergency Department (ED) in the preceding 12 months; 5) three or more positive responses on skin prick allergy testing; 6) an elevated IgE level; 7) oxygen saturation on presentation < or =91%; 8) longer duration of asthma; 9) lower level of maternal education; 10) an admission during autumn; 11) three or more siblings; and 12) being prescribed antibiotics. Risk factors that remained significant on multivariate analysis were three or more presentations to the ED in the preceding 12 months (P=0.003), an elevated IgE level (P=0.01), oxygen saturation on presentation < or =91% (P=0.003), and longer asthma duration (P=0.02). ICU patients took longer to see a doctor and to commence oral steroids. No differences were found between cases and controls in the proportion taking preventer therapy (58% vs. 52%), provided with a written asthma action plan (32% vs. 25%), or in whom spirometry or peak flow was measured (28% vs. 42%). However, rates were low in both groups. Parental asthma knowledge was generally poor. This study identified risk factors for an ICU admission in children with asthma. A potentially preventable risk factor is a history of multiple ED presentations in the past year. Specialist referral of children with multiple ED presentations may improve asthma control and reduce the risk of an ICU admission. Background asthma management remains suboptimal in children needing hospitalization.

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.

Psychological, social and health behaviour risk factors for deaths certified as asthma: a national case-control study

BACKGROUND

Uncontrolled studies suggest that psychosocial factors and health behaviour may be important in asthma death.

METHODS

A community based case-control study of 533 cases, comprising 78% of all asthma deaths under age 65 years and 533 hospital controls individually matched for age, district and asthma admission date corresponding to date of death was undertaken in seven regions of Britain (1994-98). Data were extracted blind from anonymised copies of primary care records for the previous 5 years and non-blind for the earlier period.

RESULTS

60% of cases and 63% of controls were female. The median age in both groups was 53. Cases had an earlier age of asthma onset, more chronic obstructive lung disease, and were more obese. 48% of cases and 42% of controls had a health behaviour problem; repeated non-attendance/poor inhaler technique was related to increased risk of death. Overall, 85% and 86%, respectively, had a psychosocial problem. Four psychosocial factors were associated with increased risk of death (psychosis, alcohol/drug abuse, financial/employment problems, learning difficulties) and two with reduced risk (anxiety/prescription of antidepressant drugs and sexual problems). While alcohol/drug abuse lost significance after adjustment for psychosis, other associations appeared independent of each other and of indicators of severity and co-morbidity. None of the remaining 13 factors including family problems, domestic abuse, bereavement, and social isolation were significantly related to risk of asthma death.

CONCLUSION

There was an apparently high burden of psychosocial problems in both cases and controls. The associations between health behaviour, psychosocial factors, and asthma death are varied and complex with a limited number of factors showing positive relationships.

Cardiovascular side effects of inhaled salbutamol in hypoxic asthmatic patients

BACKGROUND

Beta-2 adrenoceptor agonists have been associated with sudden death in asthma patients but the cause and underlying mechanism are unclear. Animal experiments indicate that the combination of hypoxia and beta2 agonists may result in detrimental cardiovascular effects. A study was undertaken to investigate the effect of hypoxia on the systemic vascular effects of salbutamol in patients with asthma who are hypoxic by assessing forearm blood flow (FBF) as a measure of peripheral vasodilatation.

METHODS

Eight men with mild asthma underwent the following treatments: normoxia + placebo (NP), normoxia + salbutamol (NS), hypoxia + placebo (HP), and hypoxia + salbutamol (HS). The period of mask breathing started at t=0 minutes, lasted for 60 minutes, and at 30 minutes 800 microg salbutamol was inhaled. The experiment was completed 30 minutes after the inhalation (t=60 minutes). For the hypoxia treatment the SpO2 level was 82%. Differences between treatments were sought using factorial ANOVA on percentage change from the pretreatment value.

RESULTS

There were no significant differences in blood pressure and potassium levels between the treatments. After 60 minutes the increase in FBF was 13% (95% CI -12 to 39) more for HP treatment than for NP, 21% (95% CI -5 to 46) more for NS than for NP, and 32% (95% CI 7 to 58) more for HS than for HP (p=0.016). The inhalation of salbutamol during hypoxia resulted in a significant increase in FBF of 45% (95% CI 20 to 71) compared with NP (p=0.001).

CONCLUSION

Patients with asthma who are hypoxic and inhale beta2 agonists have serious systemic vascular side effects which may be an additional explanation for the association between asthma treatment and sudden death.

Cardiovascular side effects of inhaled salbutamol in hypoxic asthmatic patients

BACKGROUND

Beta-2 adrenoceptor agonists have been associated with sudden death in asthma patients but the cause and underlying mechanism are unclear. Animal experiments indicate that the combination of hypoxia and β2 agonists may result in detrimental cardiovascular effects. A study was undertaken to investigate the effect of hypoxia on the systemic vascular effects of salbutamol in patients with asthma who are hypoxic by assessing forearm blood flow (FBF) as a measure of peripheral vasodilatation.

METHODS

Eight men with mild asthma underwent the following treatments: normoxia + placebo (NP), normoxia + salbutamol (NS), hypoxia + placebo (HP), and hypoxia + salbutamol (HS). The period of mask breathing started at t=0 minutes, lasted for 60 minutes, and at 30 minutes 800 μg salbutamol was inhaled. The experiment was completed 30 minutes after the inhalation (t=60 minutes). For the hypoxia treatment the Spo2 level was 82%. Differences between treatments were sought using factorial ANOVA on percentage change from the pretreatment value.

RESULTS

There were no significant differences in blood pressure and potassium levels between the treatments. After 60 minutes the increase in FBF was 13% (95% CI –12 to 39) more for HP treatment than for NP, 21% (95% CI –5 to 46) more for NS than for NP, and 32% (95% CI 7 to 58) more for HS than for HP (p=0.016). The inhalation of salbutamol during hypoxia resulted in a significant increase in FBF of 45% (95% CI 20 to 71) compared with NP (p=0.001).

CONCLUSION

Patients with asthma who are hypoxic and inhale β2 agonists have serious systemic vascular side effects which may be an additional explanation for the association between asthma treatment and sudden death.

Prevalence of asthma among schoolchildren in Patras, Greece: three surveys over 20 years

BACKGROUND

The aim of the present study was to compare the prevalence of asthma among schoolchildren in 1978, 1991, and 1998 in Patras, Greece.

METHODS

The study populations of the three comparable cross sectional surveys comprised third and fourth grade public school children in Patras, Greece. Sample sizes in 1978, 1991, and 1998 were 3735, 2952 and 3397 children and response rates were 80.4%, 81.9%, and 90.6%, respectively. Prevalence of current, non-current, and lifetime asthma or recurrent wheezing was determined by parental questionnaire. Personal communication with the parents of asthmatic children in 1991 and 1998 provided data on lost schooldays.

RESULTS

Prevalence rates of current asthma or wheezing in 1978, 1991, and 1998 were 1.5%, 4.6%, and 6.0%, respectively (1978-91: p=0.01, 1991-98: p=0.02, 1978-98: p=0.03). Lifetime prevalences of asthma or wheezing in 1991 and 1998 were 8.0% and 9.6%, respectively (p=0.03). Current diagnosed asthma increased proportionally to diagnosed wheezing during 1991-98. The number of schooldays lost in the previous 2 years because of asthma did not change (p>0.1) between 1991 (0.31 per child) and 1998 (0.34 per child).

CONCLUSIONS

Our results support a true increase in the prevalence of current and lifetime asthma in the last 20 years among pre-adolescent children in Patras, Greece.