Death from asthma: rare but real

Risk factors for death in patients with severe asthma

OBJECTIVE:

To identify risk factors for death among patients with severe asthma.

METHODS:

This was a nested case-control study. Among the patients with severe asthma treated between December of 2002 and December of 2010 at the Central Referral Outpatient Clinic of the Bahia State Asthma Control Program, in the city of Salvador, Brazil, we selected all those who died, as well as selecting other patients with severe asthma to be used as controls (at a ratio of 1:4). Data were collected from the medical charts of the patients, home visit reports, and death certificates.

RESULTS:

We selected 58 cases of deaths and 232 control cases. Most of the deaths were attributed to respiratory causes and occurred within a health care facility. Advanced age, unemployment, rhinitis, symptoms of gastroesophageal reflux disease, long-standing asthma, and persistent airflow obstruction were common features in both groups. Multivariate analysis showed that male gender, FEV₁ pre-bronchodilator < 60% of predicted, and the lack of control of asthma symptoms were significantly and independently associated with mortality in this sample of patients with severe asthma.

CONCLUSIONS:

In this cohort of outpatients with severe asthma, the deaths occurred predominantly due to respiratory causes and within a health care facility. Lack of asthma control and male gender were risk factors for mortality.

Hearing half the message? A re-audit of the care of patients with acute asthma by emergency ambulance crews in London

PROBLEM

An initial audit of the care provided to emergency asthma patients by the ambulance service was carried out in 1996. Some under-recognition and under-treatment of severe asthma was found as well as a lack of documentation of patient condition on scene. A re-audit was undertaken in 1999.

DESIGN

A multidisciplinary advisory group was reconvened. The same method was adopted as for the first audit. Patients included were those administered nebulised salbutamol by crews in the catchment areas of four hospitals and those diagnosed with asthma at the Accident & Emergency (A&E) departments of those hospitals between January and March 1999.

SETTING

London Ambulance Service.

KEY MEASURES FOR IMPROVEMENT

(1) Accuracy of diagnosis and appropriateness of treatment, and (2) adherence to protocol.

STRATEGIES FOR CHANGE

Following the first audit, treatment protocols were widened and brought into line with the British Thoracic Society guidelines for care of acute asthma patients. The results were widely disseminated within the service and training was initiated for all operational staff.

EFFECTS OF CHANGE

The number of patients included in the re-audit more than doubled (audit 1: n = 252, audit 2: n = 532). The increase occurred exclusively in those administered nebulised salbutamol by ambulance crews but diagnosed with conditions other than asthma in A&E (audit 1: n = 15, audit 2: n = 161). The proportion of patients diagnosed with asthma in A&E who were administered nebulised salbutamol by their attending crew rose from 58% to 75%. However, 43 asthma patients were not treated; several of these were not recognised as suffering from asthma and others fell within the changed protocols for treatment. Adherence to protocol for administration of salbutamol remained high. Pre-hospital documentation of key observations did not improve.

LESSONS LEARNT

Messages from the first audit seem to have been acted upon selectively. Implementing change is complex, and re-audit is necessary to understand the effects of the changes made.

The management of acute severe asthma

Asthma is a common cause of morbidity and mortality in the United States, with over two million Emergency Department (ED) visits each year. Airway inflammation is recognized as a major component in the pathophysiology of asthma. The classic presentation of asthma is that of wheezing, cough, and dyspnea, however, the severity of airflow limitation correlates poorly with clinical signs. Forced exhaled volume in 1 s (FEV(1)) and the peak expiratory flow rate (PEFR) are direct reflections of the severity of airflow obstruction and are the standard measures used in the ED to assess the severity of airflow obstruction and the response to therapy. Beta2-adrenergic bronchodilators, ipratropium bromide, and corticosteroids form the cornerstone of therapy. Inhaled corticosteroids, leukotriene modifying drugs, and noninvasive positive pressure ventilation should be considered in patients with severe disease and in those who have responded poorly to standard therapy. Mechanical ventilation is usually well tolerated and may be lifesaving in patients with refractory asthma. Precautions are required to prevent dynamic hyperinflation during assisted ventilation.

External chest compression in the management of acute severe asthma--a technique in search of evidence

Compelling anecdotal evidence exists for the potentially lifesaving benefits of mechanical external chest compression (MECC), but no published trials of the technique exist. The history and technique for MECC are discussed and illustrated by a case report. Although the technique is not discussed in the Resuscitation Guideline 2000, and the need for it within the intensive care unit has reduced, the use of MECC will have its greatest impact when initiated in the prehospital setting for patients suffering from severe, sudden-onset, asphyxic asthma.

Comparing the performance of two indices for spatial model selection: application to two mortality data

The statistical analysis of spatially correlated data has become an important scientific research topic lately. The analysis of the mortality or morbidity rates observed at different areas may help to decide if people living in certain locations are considered at higher risk than others. Once the statistical model for the data of interest has been chosen, further effort can be devoted to identifying the areas under higher risks. Many scientists, including statisticians, have tried the conditional autoregressive (CAR) model to describe the spatial autocorrelation among the observed data. This model has greater smoothing effect than the exchangeable models, such as the Poisson gamma model for spatial data. This paper focuses on comparing the two types of models using the index LG, the ratio of local to global variability. Two applications, Taiwan asthma mortality and Scotland lip cancer, are considered and the use of LG is illustrated. The estimated values for both data sets are small, implying a Poisson gamma model may be favoured over the CAR model. We discuss the implications for the two applications respectively. To evaluate the performance of the index LG, we also compute the Bayes factor, a Bayesian model selection criterion, to see which model is preferred for the two applications and simulation data. To derive the value of LG, we estimate its posterior mode based on samples derived from the BUGS program, while for Bayes factor we use the double Laplace-Metropolis method, Schwarz criterion, and a modified harmonic mean for approximations. The results of LG and Bayes factor are consistent. We conclude that LG is fairly accurate as an index for selection between Poisson gamma and CAR model. When easy and fast computation is of concern, we recommend using LG as the first and less costly index.

[Hospital admission for asthma. Descriptive analysis and prognostic factors after discharge]

BACKGROUND

Few authors have looked at admissions in Spain of patients with acute asthma attacks. The aim of this study was to determine the clinical profile of such patients and analyze factors influencing disease course after release.

METHODS

Asthmatics admitted to our hospital were enrolled prospectively over 12 consecutive months. The patients were telephoned one and four months after release. Demographic and clinical data were collected in addition to data on exacerbations, readmissions, treatment and medical follow-up.

RESULTS

Sixty-five patients (44 women and 21 men, mean age 45, SD 19). Most (54%) were admitted in autumn and the most common cause of exacerbation was respiratory tract infection (68%). Before admission, 54% had severe asthma, 32% had moderate asthma and 14% had mild asthma. At least one exacerbation occurred for 54% of patients, while 38% required emergency assistance and 19% were readmitted. Two patients (3%) died of asthma. Multiple factor logistic regression analysis showed a relation between the appearance of exacerbation after release and greater severity of asthma and the absence of long-lasting (beta-adrenergic drugs. Readmission was related to shorter duration of treatment with oral glucocorticoids after release and a higher number of prior hospital admissions.

CONCLUSIONS

1) Admission due to asthma occurs mainly in autumn and is probably related to respiratory infections, rather than exclusively to severe asthma. 2) After release, short-term morbidity and mortality due to the disease are high. 3) Disease severity itself and inadequate treatment are both related to poor clinical course after release.