Fatal asthma--is treatment incriminated?

Severity Stratification in Life-threatening Asthma

Severity differences may in part explain the large varia tions in asthma mortality that occur in different coun tries. This study examines the use of APACHE II for measuring asthma severity in 118 adult asthma admis sions at one intensive care unit in New Zealand during 1987-1988. Most admissions were hypercapnic (72%), and 61 % had an altered level of consciousness. Mean APACHE II score was 20 in the emergency department and 12 upon ICU admission. We summarize the extent of physiological derangement using four acute physiol ogy score (APS) ranges. Each APS range stratified admis sions into groups with differing clinical course, therapy, and outcome. These results document a high level of asthma severity among patients treated in New Zealand, the country with the world's highest asthma mortality. APACHE II provides a valid and reproducible measure of asthma severity and should be useful for describing and comparing international differences in asthma severity and as a case-mix control in studies of asthma therapy.

Determinants of near fatality in acute severe asthma

PURPOSE

The data extrapolated from cases of acute severe asthma that narrowly miss being fatal may prove valuable in the identification of the factors implicated in mortality. The purpose of this study was, therefore, to identify determinants of near fatality in patients with acute severe asthma.

PATIENTS AND METHODS

We studied 81 patients with acute severe asthma in whom mechanical ventilation was required. Near fatality was defined as the occurrence of respiratory arrest and/or coma necessitating emergency tracheal intubation and resuscitation. In the cases that were not regarded as near fatal, tracheal intubation was performed electively because of deteriorating arterial blood gas values and/or the anticipation of exhaustion. Various continuous and categorical variables were compared in these two groups of patients. Patients with a hyperacute attack (period from onset of attack to mechanical ventilation less than 3 hours) were specifically sought and studied to determine the impact of such a course on near fatality.

RESULTS

The "attack duration" (period from onset of attack to mechanical ventilation) was an important determinant of near fatality and of the subsequent clinical course. It was shorter in the group with a near-fatal episode (p < 0.03), and hyperacute attacks were uniformly near fatal. The attack duration correlated positively with the duration of the requirement for mechanical ventilation (p < 0.01). A longer attack duration was associated with an increased likelihood of the occurrence of major atelectasis (p < 0.01). There was no evidence of a relationship between near fatality and the side effects of bronchodilators as regards hypokalemia, arrhythmias, or cardiotoxicity. There was evidence of considerable under-treatment in the patient population as a whole, particularly in regard to the use of corticosteroids.

CONCLUSIONS

A short attack duration is associated with an increased risk of near fatality in acute severe asthma. This is particularly evident in hyperacute attacks. Hyperacute attacks resolve rapidly once bronchodilator therapy has been instituted, suggesting that smooth muscle spasm is the predominant pathogenetic mechanism. The importance of routine anti-inflammatory therapy in mild to moderate asthma requires re-emphasis but, in addition, all patients should be provided with, and educated in the use of, bronchodilator rescue therapy, which should be available at all times. Despite current trends, the use of regular, prophylactic bronchodilator therapy in strict conjunction with anti-inflammatory agents may still be indicated. There is little evidence in the present data obtained from near-fatal cases to support the concept that cardiotoxicity related to bronchodilators contributes significantly to mortality from asthma.

Can fatal asthma be prevented?--a personal view

An increase in the mortality rate from asthma in several countries has been observed in recent years, notwithstanding the great improvement in pathophysiological findings and the introduction of new effective therapeutic agents. The phenomenon is difficult to explain but the causes of death and identification of high-risk patients have been widely studied. It is suggested that the most vital aim for physicians is the avoidance of those factors which may contribute to death from asthma. These are particularly: inadequate assessment of its severity by patients, general practitioners and hospital doctors, and inadequate and inappropriate treatment. From the diagnostic point of view, the measurement of airflow rates is necessary to establish the diagnosis in terms of reversibility, quantify the severity and assess the response to therapy. The different entity of reversibility of bronchial obstruction is due to the various mechanisms intervening in different patients. After adequate treatment, according to our observations, the reversibility is more complete in young people and when the duration of the disease is less than 2 years. Trigger factors must also be considered. From the therapeutic point of view, considering that the most important alteration in asthma is the inflammation of bronchial structures with intervention of several inflammatory cells and of numerous different chemical mediators, physicians have to apply treatment aimed at reducing inflammation rather than relying on symptomatic bronchodilator remedies. Treatment should be divided into three phases, according to symptoms: induction, consolidation and maintenance. Finally, on the basis of data here presented and of clinical experience, the essential measures for the prevention of asthma mortality are reported. If general practitioners take them into account, deaths from asthma will be reduced to a minimum.

The use of beta-agonists and the risk of death and near death from asthma

BACKGROUND

Morbidity and mortality from asthma appear to be increasing, and it has been suggested that medications used to treat asthma are contributing to this trend. We investigated a possible association between death or near death from asthma and the regular use of beta 2-agonist bronchodilators.

METHODS

Using linked health insurance data bases from Saskatchewan, Canada, we conducted a matched case-control study of subjects drawn from a cohort of 12,301 patients for whom asthma medications had been prescribed between 1978 and 1987. We matched 129 case patients who had fatal or near-fatal asthma with 655 controls (who had received medications for asthma but had not had fatal or near-fatal events) with respect to region of residence, age, receipt of social assistance, and previous hospitalization for asthma.

RESULTS

The use of beta-agonists administered by a metered-dose inhaler was associated with an increased risk of death from asthma (odds ratio, 2.6 per canister per month; 95 percent confidence interval, 1.7 to 3.9) and of death or near death from asthma, considered together (odds ratio, 1.9; 95 percent confidence interval, 1.6 to 2.4). For death from asthma, use of the beta-agonist fenoterol was associated with an odds ratio of 5.4 per canister, as compared with 2.4 for the beta-agonist albuterol. On a microgram-equivalent basis, the odds ratio for this outcome with fenoterol was 2.3, as compared with 2.4 with albuterol.

CONCLUSIONS

An increased risk of death or near death from asthma was associated with the regular use of inhaled beta 2-agonist bronchodilators, especially fenoterol. Regardless of whether beta-agonists are directly responsible for these adverse effects or are simply a marker for more severe asthma, heavy use of these agents should alert clinicians that it is necessary to reevaluate the patient's condition.

Temporal trends in chronic obstructive lung disease case fatality in hospitalized US veterans: 1970-1987

Vital statistics data have suggested that age-adjusted mortality from chronic obstructive lung diseases (CLD) is increasing. The present investigation has used the US Veterans Administration (VA) hospital computer database to determine whether trends in CLD case fatality follow trends in CLD population mortality. Data for male patients discharged from 172 VA hospitals from 1970 through 1987 were utilized. Patients were included if they had a CLD as a first-listed hospital discharge diagnosis, did not have any of a number of smoking-related cardiovascular or malignant diseases, and were born in the years 1900 through 1939. While crude case fatality for all CLD increased from 5.2 percent in 1970 to 7.4 percent in 1987, age-adjusted case fatality decreased from a peak of 8.5 percent in 1971 to 5.8 percent (95 percent confidence interval, 5.4 to 6.61 percent) in 1987. This trend was seen for all CLD diagnoses, including asthma. Age-specific case fatality decreased for each successive 5-year birth cohort, and age at death remained relatively constant over the last 14 years of the study. The declining case fatality could not be explained by changes in the ICD coding rubrics. The extent to which case fatality has been declining due to improved treatment and/or cohort-related changes in tobacco smoke exposure could not be determined definitively from the data.