Correspondence
Patterns of Mortality from Asthma
N Engl J Med 1995; 332:1379-1381May 18, 1995
- Article
To the Editor:
The long-term studies of morbidity from asthma by Silverstein et al.1 and Lang and Polansky2 (Dec. 8 issue) do not provide evidence of a history of either active or passive smoking that is based on explicit criteria. Silverstein et al. based their diagnosis of asthma in part on evidence of “no current smoking (for patients of 14 years or older).” Neither a history of passive smoking nor the prevalence of active cigarette smoking among adolescents and children less than 14 years of age is mentioned.3,4 Furthermore, the use of patients' reports of cigarette consumption may be an insufficient means of assessing smoking status, falsely classifying both smokers and nonsmokers.5
The study by Lang and Polansky provides no data at all regarding smoking. The authors of these reports and an accompanying editorial6 do not raise the real possibility that the accuracy of the diagnosis of asthma, the course of the disease, and morbidity rates may have been significantly affected by differences across time in the rates of cigarette smoking and passive cigarette smoking in patients and control populations. Numerous reports have quantified the adverse effects of active cigarette smoking on morbidity from asthma; several recent studies of young people and adults have reported significant links between passive smoking and the presence of asthma symptoms and adverse effects on respiratory function.7,8 In view of this substantial body of knowledge, it is important that studies of patients with asthma include adequate data regarding smoking history, both active and passive.
8 ReferencesSteven J. Jay, M.D.
Indiana University School of Medicine, Indianapolis, IN 46202-51141
Silverstein MD ,Reed CE ,O'Connell EJ ,Melton LJ III ,O'Fallon WM ,Yunginger JW . Long-term survival of a cohort of community residents with asthma. N Engl J Med 1994;331:1537-1541
Full Text | Web of Science | Medline2
Lang DM ,Polansky M . Patterns of asthma mortality in Philadelphia from 1969 to 1991. N Engl J Med 1994;331:1542-1546
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Burchfiel CM ,Higgins MW ,Keller JB ,Howatt WF ,Butler WJ ,Higgins IT . Passive smoking in childhood: respiratory conditions and pulmonary function in Tecumseh, Michigan. Am Rev Respir Dis 1986;133:966-973
Web of Science | Medline4
Bailey SL . Adolescents' multisubstance use patterns: the role of heavy alcohol and cigarette use. Am J Public Health 1992;82:1220-1224
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Perez-Stable EJ ,Marin G ,Marin BV ,Benowitz NL . Misclassification of smoking status by self-reported cigarette consumption. Am Rev Respir Dis 1992;145:53-57
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Buist AS ,Vollmer WM . Preventing deaths from asthma. N Engl J Med 1994;331:1584-1585
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Weiss ST . Environmental tobacco smoke and asthma. Chest 1993;104:991-992
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Robbins AS ,Abbey DE ,Lebowitz MD . Passive smoking and chronic respiratory disease symptoms in non-smoking adults. Int J Epidemiol 1993;22:809-817
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To the Editor:
The articles by Silverstein et al. and Lang and Polansky provide a balanced view of asthma and deaths from asthma in two places: Olmsted County, Minnesota, and Philadelphia. The Olmsted County report indicates that deaths from asthma in that community are rare and that survival among patients with asthma is not significantly different from expected survival. On the other hand, the report from Philadelphia indicates rising mortality from asthma centered in urban census tracts with high percentages of poor, minority residents.
I was concerned by the editorial in the same issue.1 In their commentary, Drs. Buist and Vollmer state that “mortality from asthma is not itself a major problem in the United States; rates of death are very low for the population as a whole, and even among people with asthma the disease is not a common cause of death.” They go on to add “no, mortality is not the problem, morbidity is.” The controversy such statements should evoke is apparent. First, the report from Olmsted County, Minnesota, contains no information on the race or ethnicity of patients who died. However, the residents of this county are primarily white and generally of average income. The community of physicians caring for patients with asthma cannot ignore the rising mortality among residents of poor urban areas, especially blacks and Hispanics. How can we tell a mother in North Philadelphia whose child has died of asthma that mortality from asthma is not the problem? Of course, morbidity from asthma remains an equally important issue. Morbidity leads to lost days of school or work, as well as substantial health care costs for care delivered in emergency rooms and in the hospital. I would point out that where there is mortality from asthma, there is morbidity. To downplay the rising rates of mortality from asthma (despite its overall rarity) ignores a tragic problem plaguing our urban populations.
1 ReferencesGregory C. Kane, M.D.
Jefferson Medical College, Philadelphia, PA 19107-50831
Buist AS ,Vollmer WM . Preventing deaths from asthma. N Engl J Med 1994;331:1584-1585
Full Text | Web of Science | Medline
To the Editor:
Drs. Buist and Vollmer emphasize the role of residential environmental factors in the increasing rates of morbidity and mortality from asthma observed over the past decade. We wish to underscore that exposures in the work environment are also important in precipitating and exacerbating asthma. Exposures at work are estimated to cause between 2 and 15 percent of all cases of asthma in adults.1 In the United Kingdom, asthma is the most common work-related respiratory condition reported to a national surveillance system, making up 28 percent of cases.2 Among 13 U.S. clinics specializing in occupational and environmental diseases, asthma and related diagnoses represented 38 percent of all non–asbestos-related occupational respiratory disorders.3
Asthma can develop in workers after sensitizing or nonsensitizing exposures through the respiratory tract.1 Sensitizing exposures to a wide variety of airborne chemicals and plant or animal proteins occur in many different industries. Isocyanates alone account for approximately 20 percent of cases of occupational asthma reported in both the United Kingdom2 and the United States.3 Irritant exposures occur in numerous work environments.
In addition to the precipitation of new cases of asthma, episodes of bronchospasm triggered by exposure at work to dusts, fumes, and other irritants, as well as by extreme temperatures, can occur in patients with preexisting asthma.
3 ReferencesEdward L. Petsonk, M.D.
Robert M. Castellan, M.D., M.P.H.
Gregory R. Wagner, M.D., M.P.H.
National Institute for Occupational Safety and Health, Morgantown, WV 26505-28451
Bernstein IL, Chan-Yeung M, Malo J-L, Bernstein DI, eds. Asthma in the workplace. New York: Marcel Dekker, 1993.
2
Merideth SK ,McDonald JC . Work-related respiratory disease in the United Kingdom, 1989-1992: report on the SWORD project. Occup Med 1994;44:183-189
CrossRef3
Division of Respiratory Disease Studies. Work-related lung disease surveillance report, 1994. Cincinnati: National Institute for Occupational Safety and Health, 1994. (DHHS publication no. (NIOSH) 94-120.)
Author/Editor Response
The authors reply:
To the Editor: In our study, the diagnosis of asthma was based on clinical evidence of airway disease, substantial variability in airflow obstruction, and the presence of two or more of several additional criteria suggesting the presence of allergy and the absence of other conditions causing airflow obstruction, which included smoking.1
Our cohort of 2499 subjects was predominantly young (median age, 4 years), and we believe the information in the medical records at the time of the patients' diagnostic evaluations and medical visits for respiratory symptoms was sufficient to permit a reasonably accurate classification of the patients as having asthma.2 Unfortunately, we did not have information on smoking status during the follow-up period, and because smoking status in the young cohort may have changed over the period of observation, we did not include smoking as a covariate in our analysis of survival.
Smoking is the leading preventable cause of death in the United States, and it is well known that both smoking and passive exposure to smoke are associated with increased morbidity among patients with asthma and an overall excess in the number of deaths.3 Thus, the problem is not in documenting the adverse effects of smoking, but in quantitating and recording personal exposures to cigarette smoke. Prospective studies that include objective measurements such as the volume of expired carbon monoxide and urinary cotinine concentrations are necessary to control for the effects of smoking as compared with the effects of other environmental agents on the course of asthma.
3 ReferencesMarc D. Silverstein, M.D.
John W. Yunginger, M.D.
Mayo Clinic, Rochester, MN 559051
Yunginger JW ,Reed CE ,O'Connell EJ ,Melton LJ III ,O'Fallon WM ,Silverstein MD . A community-based study of the epidemiology of asthma: incidence rates, 1964-1983. Am Rev Respir Dis 1992;146:888-894
Web of Science | Medline2
Beard CM ,Yunginger JW ,Reed CE ,O'Connell EJ ,Silverstein MD . Interobserver variability in medical record review: an epidemiological study of asthma. J Clin Epidemiol 1992;45:1013-1020
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Council on Scientific Affairs, American Medical Association
CrossRef | Medline
Author/Editor Response
The health risks associated with active smoking are well documented. The deleterious effects of passive cigarette smoking on adults and children with asthma, which include increased asthma symptoms and emergency room visits,1-3 have also been demonstrated. Exposure to parental smoking is common among black and Hispanic children in urban areas.3,4
In our study, we did not evaluate individual-level risk factors for mortality from asthma. However, our univariate model demonstrated a clear and statistically significant (P = 0.01) inverse gradient in the rates of mortality from asthma across census tracts classified according to the proportions of Philadelphia residents with high-school diplomas. Since educational attainment is the best sociodemographic predictor of smoking behavior,5 our observations support the contention that future public health efforts to reduce mortality and morbidity from asthma in urban areas should include culturally sensitive antismoking interventions.
5 ReferencesDavid M. Lang, M.D.
Marcia Polansky, Sc.D.
Hahnemann University, Philadelphia, PA 19102-11921
Evans D ,Levison MJ ,Feldman CH , et al. The impact of passive smoking on emergency room visits of urban children with asthma. Am Rev Respir Dis 1987;135:567-572
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Jindal SK ,Gupta D ,Singh A . Indices of morbidity and control of asthma in adult patients exposed to environmental tobacco smoke. Chest 1994;106:746-749
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Evans R III . Asthma among minority children: a growing problem. Chest 1992;101:Suppl:368S-371S
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Wood PR ,Hidalgo HA ,Prihoda TJ ,Kromer ME . Hispanic children with asthma: morbidity. Pediatrics 1993;91:62-69
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Smokers' beliefs about the health benefits of smoking cessation -- 20 US. communities, 1989. MMWR Morb Mortal Wkly Rep 1990;39:653-656
Medline
Author/Editor Response
Dr. Kane argues with our assertion that mortality from asthma is not itself a major problem in the United States. We agree that even one preventable death is an unacceptable tragedy. The intent of our comments was to focus attention on the greater public health problem of the morbidity from and prevalence of asthma. Deaths from asthma are just the tip of the iceberg and cannot possibly convey the full scope of the problem.1 Even if the number of deaths from asthma was still declining, the rise in the number of hospitalizations for asthma2 and the increase in the prevalence of asthma3,4 should be cause for major concern. We wholly concur with Dr. Kane, however, when he notes that deaths from asthma draw particular attention to the impact of asthma among residents of poor urban areas, especially blacks and Hispanics.
Petsonk et al., from the National Institute for Occupational Safety and Health, correctly underscore the importance of the exposures in the work environment in precipitating new cases of asthma and in exacerbating preexisting cases. Although temporal trends in such exposures may explain some of the observed increase in morbidity and mortality from asthma, we are unfamiliar with such data. Furthermore, such trends would not explain the marked increases in hospitalizations for asthma in children that have been seen worldwide.2
Dr. Jay makes the important point that studies of patients with asthma should include information on exposure to cigarette smoke. We agree that smoking can be an important confounding variable in epidemiologic studies. Unfortunately, adequate information on smoking is typically not available in many such studies. For example, studies that use death-certificate data do not have access to this information, and studies that involve a review of medical records fare little better, since information about active smoking is not consistently available and information on passive exposure to smoke is virtually never available. These points highlight the need for better documentation of exposure to smoke in medical records, in terms of managing asthma as well as other disorders.
Changes in the pattern of smoking over time could help explain some of the increases seen in morbidity from asthma and possibly mortality. For example, an increase in smoking among young mothers might help account for some of the increases that have been seen in hospitalizations for asthma among children.5 The marked increase since World War II in the number of women who smoke has resulted in an appreciable increase in the prevalence and incidence of chronic obstructive pulmonary disease and coexisting asthma and chronic obstructive pulmonary disease, which may also help explain the patterns we have observed.
5 ReferencesA. Sonia Buist, M.D.
Oregon Health Sciences University, Portland, OR 97201William M. Vollmer, M.D.
Kaiser Permanente Center for Health Research, Portland, OR 972271
Vollmer WM ,Osborne ML ,Buist AS . Uses and limitations of mortality and health care utilization statistics in asthma research. Am J Respir Crit Care Med 1994;149:Suppl:S79-S87
Web of Science | Medline2
Weiss KB ,Gergen PJ ,Wagener DK . Breathing better or wheezing worse? The changing epidemiology of asthma morbidity and mortality. Annu Rev Public Health 1993;14:491-513
CrossRef | Web of Science | Medline3
National Heart, Lung, and Blood Institute. Data fact sheet: asthma statistics. Bethesda, Md.: NHLBI Education Programs Information Center, 1989.
4
Gergen PJ ,Mullally DI ,Evans R III . National survey of prevalence of asthma among children in the United States, 1976 to 1980. Pediatrics 1988;81:1-7
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Martinez FD ,Antognoni G ,Macri F , et al. Parental smoking enhances bronchial responsiveness in nine-year-old children. Am Rev Respir Dis 1988;138:518-523
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