Can Fatal Asthma Be Prevented?

Transcription

1 Can Fatal Asthma Be Prevented? P. Barriot, B. Riou, and P. Duroux Introduction Asthma in France is a common disease which affects approximately 3 to 4 percent of the population and carries considerable morbidity. But, only in the past 50 years has fatal asthma been recognized. It represents a rare complication of asthma, but it assumes considerable importance because of the high prevalence of asthma. The socio-economic impact of death caused by asthma is important, because the mortality rate from asthma is high and has increased over the past 25 years in many developed countries despite new treatment regimes, and because many of these deaths occur in young and otherwise healthy people. Moreover, most deaths from asthma appear to be largely preventable. The aim of this chapter is to summarize current findings concerning fatal asthma, and our own recent experience in its prevention. Epidemiology The mortality rate from asthma differs from one country to another (Fig. 1). Differences in prevalence of asthma were thought to explain differences in the INCIDENCE OF FATAL ASTHMA PER o ~--~----~----~'----~ '~~~' --~' --~' --~' --~' --~~' NEW ZEA LAND F;:;:;:;:;:;:;:;:;:;:;::::;:;:::;::::: ::::: ::;:;:;:3 AUSTRALIA ~;:::;:::::;3 ENGLAND E:;:;:;:;j w. GERMANY E:;:;:;:;:;] FRANCE [8] CANADAD USAfl Yrs I ~ ~ 1980 Fig. 1. Deaths from asthma in various countries, in five to 34 year old patients and in patients of all ages during the year (From Riou et ai., L'asthme mortel, Rev Mal Resp; in press) J. L. Vincent (ed.), Update 1988 Springer-Verlag Berlin Heidelberg 1988

2 168 P. Barriot et al. mortality rate [1]. The highest mortality rates occur in New-Zealand, whereas the lowest rates have been reported in the USA In Europe, mortality rates appear to be similar in England and Wales, West Germany, and France, i.e. 3 to 4 deaths per habitants. Since the 1960s, many studies have addressed the problem of the increasing mortality rate from asthma [2], and now there is some agreement that this trend is real and cannot be explained by differences in disease classification, or inaccurate death certificates. Moreover, a recent study [3] has shown a further increase in mortality during in England and Wales. The reason why fatalities from asthma have increased remains unknown but the possibility that its prevalence and severity have changed cannot be excluded. There are few studies which document fatal asthma in a large asthmatic population. An early study by MacCracken [4] reported a mortality rate of whereas Alderson and Loy [5] have recently reported a mortality rate of ; Blair [6] reported a mortality rate of in asthmatic children. Fatal asthma may occur in the hospital, as a complication of status asthmaticus. The mortality rate of status asthmaticus ranges from 39% [7] to 0% [8]. A 10 to 15% mortality rate in patients with status asthmaticus requiring mechanical ventilation is not unusual. A final point concerns the outcome of patients who suffered from status asthmaticus and were discharged alive from the hospital. Bousser et al. [9] have reported a mortality of 41 % in these patients, 8 years after hospital discharge. Risk Factors for Fatal Asthma Many studies [2] have attempted to identify factors which characterize asthmatic patients who are at high risk of death but most of them did not include control groups. Nevertheless two recent studies [10, 11] that included control groups have confirmed earlier findings. A long history of asthma, a previous life-threatening attack, recent emergency hospital admission, poor medical management, poor compliance with treatment, lack of adequate objective evaluation of the severity of airway limitation, poor perception of airway limitation, and delay in hospital admission, are thought to be risk factors [2, 10, 11]. Nevertheless, fatal asthma may occur suddenly in patients not having any recognized risk factors. In our study [12], only 10% of patients with fatal asthma required mechanical ventilation previously, and in 43% no contributing factor was found. Since the 1960s, the increase in deaths from asthma has been attributed to an increase in the use of pressurized aerosols containing sympathomimetic agents [2]. However, major errors in methodology were discovered in these earlier studies, and the relationship between fatalities from asthma aerosols containing sympathomimetic agents has been questioned by recent and well-conducted studies. Esdaile et al. [13] have reviewed this problem and concluded that the causal link between fatal asthma pressurized aerosols containing sympathomimetic was not supported by any scientific evidence. The consequences of earlier alarmist reports are still present, and many explain why many patients and physicians are still reluctant to use pressurized sympathomimetic aerosols extensively.

3 Can Fatal Asthma Be Prevented? 169 A poor perception of the severity of airflow limitation by the asthmatic patients has been emphasized in cases of fatal asthma. Rubinfeld and Pain [14] have shown that IS% of asthmatic patients were unable to detect a SO% limitation of airflow. Nevertheless, most of the studies which concluded in poor selfassessment of the severity of the attack also underline the long delay in hospital admission, which is not under the asthmatic patient's control. There is evidence that asthmatic patients are capable of assessing their condition: 1. in the retrospective portion of our study [12], we observed that 9% of asthmatic patients who called our prehospital emergency care unit died; 2. in the prospective part of our study, 8S% of asthmatic patients who called had a peak expiratory flow value less than ISO mllmin demonstrating that they were actually critically ill. Psychological factors appear to be important also since they affect medical management, compliance, and behavior during a severe attack of asthma. Characteristics of the Fatal Attack of Asthma Many fatal attacks of asthma have a sudden unexpected onset. Deaths have been reported to occur within 30 min in 2S% [2] to 6S% [12] of patients. This suggests that fatal asthma is not necessarily related to a prolonged attack and that fatal asthma is often due to sudden severe attacks "out of a clear blue sky" as stated by Stableforth [IS]. The rapid onset of a fatal asthma attack might explain the "inaccurate" assessment of disease severity by the asthmatic patient. Moreover, Arnold et al. [16] suggested that adequate prevention of fatal asthma depends on the rapidity of onset. If fatal attacks progress slowly, it is safe to concentrate on improved management of the patient at home, whereas, if fatal attacks develop more rapidly, improvement in pre-hospital measures is more appropriate. Prevention of Fatal Asthma Retrospective studies [2] have suggested that up to 80% of deaths from asthma could be prevented, since in most cases potentially avoidable factors could be identified. However, only two studies [14, 16] have actually sought ways to decrease the mortality rate from asthma. Prevention of fatal asthma might be achieved at different but not exclusive levels (Table 1). Failure to diagnose asthma precludes effective treatments. Physicians must be aware that chronic bronchitis or COPD, and asthma are not mutually exclusive. Underdiagnosis of asthma in children should be underlined: diagnosis of asthma was offered in only 12% of children who suffered at least one episode of wheezing since starting school, and in only 3S% of children experiencing more than 12 episodes a year [17]. Failure to diagnose asthma deprives the patient of specific treatment and leaves him in real danger in case of any severe sudden attack.

4 170 P. Barriot et al. Table 1. Recommendations to prevent fatal asthma Improvement in recognition of asthma, especially in children Education of physicians Recognition of patients at high risk for fatal asthma Education of asthmatic patients - knowledge of asthma and its treatment - self-management skills - how and when to call for emergency help Improvement in therapy - preventive therapy - symptomatic treatment - self-control using peak-flow meter Improvement in prehospital management of emergency calls - self-referral admission services [l9) - systematic prehospital emergency care plans [l2) Adequate hospital care of status asthmaticus [8) Reappraisal of patients who experienced near-fatal asthma [19) The education of asthmatic patients is of major importance. Physicians must explain the purpose of each treatment (relief or prevention of symptoms) and the need to continue treatment even when the patient feels well. Teaching patients how to use inhalers is of paramount importance, but it has been shown that many patients are unable to use conventional pressurized aerosols efficiently even after careful training. In these patients, new devices, such as aerochambers, facilitate aerosol administration. Physicians must teach the asthmatic patient self-management skills: administering a short individually-adapted course of corticosteroid when he recognized sufficient deterioration, recognition of symptoms requiring emergency medical assistance, self-management' of a severe attack until the physician's arrival, including self-injection of a subcutaneous sympathomimetic agent (Bricanyl) in those patients suffering from rapid severe attacks. Definition of conditions requiring a call for emergency assistance are very important. The efficacy of both treatments, for prevention and for relief of an attack, and especially self-administered treatment during a severe attack, must be evaluated by objective measurement of airflow limitation using a home peakflow meter. Training of all physicians likely to encounter asthmatic patients is obviously necessary. A recent European audit of asthma therapy has shown large differences in physicians' view on how to treat asthma, the main contrast involves physicians in Britain and Scandinavia who prefer ~-agonists in inhalation and corticosteroids, and, on the other hand, those in France, Portugal, and some other countries who favor administration of theophylline and desensitization [18]. It must be pointed out that undertreatment (i.e. insufficient use of inhaled ~-agonists and corticosteroids) was recognized as a main risk factor for fatal asthma [2J. Corticosteroids should always be envisaged to treat patients who experience a life-threatening asthma attack. General practioners must verify the efficacy of emergency treatment of an asthma attack in the patient's home using a peak-flow meter.

5 Can Fatal Asthma Be Prevented? 171 The only two studies [12, 19] which actually decreased the mortality rate from asthma sought to improve the prehospital management of emergency call. As a matter of fact, delay at any stage of care is an important factor involved in deaths from asthma [2, 12]. Crompton et al. [19] have developed a self-admission service for asthmatic patients and reported a lower mortality rate from asthma (0,3%) than that observed in patients who used other asthma services (0.6%). But, this scheme is probably useful only in cooperative patients, and Anderson et al. [20] failed to demonstrate any improvement in the mortality rate when applying such a system of self-refferal to a population of asthmatic children. We have initiated a prospective study [12] in an effort to decrease the incidence of fatal asthma, with improvement in the prehospital management of emergency calls from asthmatic patients. This study was based on the following assumption: asthmatic patients who call an emergency care unit actually are having a severe attack that might be fatal. Thus, standardized behavior was decided, whatever the apparent severity of the attack: team of firemen (mean delay of arrival 5 min) and an ambulance with a physician (mean delay 10 min) were immediately dispatched to the asthmatic patient and he was taken to the hospital. In this manner, we obtained a 6-fold reduction in the mortality rate from asthma (Fig. 2), and during a 6-month period, 17 patients who experienced cardiorespiratory arrests were successfully resuscitated and were discharged from the hospital al Ive. Conclusion Fatal asthma clearly remains as a major health problem affecting young people and accounting for more than 1500 dealths per year in France. Moreover, mortality rates from asthma appear to have increases, despite new treatment regimes whereas mortality rates from other respiratory diseases have decreased at the 6..r::..., 5 0 s [; P- rn..r::..., 3 a 2 P<0.002 """ R 0 Fig. 2. Comparison of the mortality rate from asthma before... ell ~ 1 (mean 2.75 deaths/month) and after (mean 0.66 deaths/..~. a S month) our recommendations in the prehospital manage- ~ Z 0 U D ment of emergency calls from asthmatic patients. Dotted B A E rectangle and open circles represent the expected mortality E F X rate if patients who experienced near-fatal asthma had not F T P 0 E E been resuscitated (mean 3.5 deaths/month). Each circle R R C represents one month, and the rectangles the average. E T (From [12]) ~ til ell ""CI

6 172 P. Barriot et al. same time. Improved recognition of asthma, education of asthmatic patients and all medical personnel likely to encounter asthmatic patients, improvement in therapy, and development of patient self-referral admission services are probably necessary. But development of prehospital emergency plans are of paramount importance and can actually prevent some deaths. Emergency calls from asthmatic patients must be considered as severe attacks that may be fatal because of the lack of an accurate method to evaluate the severity of an attack that progresses rapidly, with the risk of sudden death. References 1. Woolcock AJ (1986) Worldwide differences in asthma prevalence and mortality. Chest 90:40S-45S 2. Benatar SR (1986) Fatal asthma. N Engl J Med 314: Burney PG (1986) Asthma mortality in England and Wales: evidence for a further increase Lancet 2: MacCracken D (1950) Prognosis in bronchial asthma. Br Med J 1 : Alderson M, Loy RM (1977) Mortality from respiratory disease at follow-up of patients with asthma. Br J Dis Chest 71: Blair H (1977) Natural history of childhood asthma: a 20-year follow-up. Arch Dis Child 52: Scoggin CH, Shan SA, Petty TL (1977) Status asthmaticus. A nine year experience. JAMA 238: Darioli R, Perret C (1984) Mechanically controlled hypoventilation in status asthmaticus. Am Rev Respir Dis 129: Bousser J, Reubet-Degat 0, Jeannin L (1986) Evolution a distance des etats de mal asthmatique. Reanim Soins Intens Med Urg 2:278 (Abstract) to. Rea HH, Scragg R, Jackson R, Beaglehole R, Fenwick J, Sutherland DC (1986) A casecontrol study of deaths from asthma. Thorax 41: Strunk Re, Mrazek DA, Wolfson Furhman GS, Labrecque JF (1985) Physiologic and psychological characteristics associated with deaths due to asthma in childhood: a case-controlled study. JAMA 254: Barriot P, Riou B (1987) Fatal asthma. Chest 92: Esdaile JM, Feinstein AR, Horwitz RI (1987) A reappraisal of the United Kingdom epidemic of fatal asthma. Arch Intern Med 147: Rubinfeld AR, Pain MC (1976) Perception of asthma. Lancet 1 : Stableforth D (1983) Death from asthma. Thorax 38: Arnold AG, Lane DJ, Zapata E (1982) The speed of onset and severity of acute severe asthma. Br J Dis Chest 76: Speight ANP, Lee DA, Hey EN (1983) Underdiagnosis and undertreatment of asthma in childhood. Br Med J 286: Vermeire PA, Wittesaele WM, Janssens E, De Backer WA (1986) European audit of asthma therapy. Chest 90:58S-61S 19. Crompton GK, Grant IWB, Bloomfield P (1979) Edinburgh emergency asthma admission service: report on 10 years' experience. Br Med J 2: Anderson HR, Bailey P, West S (1980) Trends in the hospital care of acute childhood asthma Br Med J 281: