---.i-~.
CHEST editorials
------
VOLUME 100 I NUMBER 6 I DECEMBER, 1991
Asthma and Work: How Do You Diagnose the Association?
diagnosis of occupational asthrna. Only one of the 57 patients reported to the Ne\\r Jersey Health Department had heen evaluated by his or her private physician with pulmonary function testing in relation to \\Tork. In another study,5 17 (17 percent) of 101 occupational asthma patients from four occupational medicine clinics had undergone puhnonary testing in relation to \vork. In the article by Henneberger et aI, the peak flo\vs \vere measured by the state health department. This is a very impractical approach. Most patients could not be tested with peak flowmeters because the physician had not reported the patient's name, the patient was no longer working, or the patient \\7as unable to be away from work for the recomrnended hvo \\7eeks. Additionally, the patients were already being treated by the tiole they \\Tere referred to the state health department. Treatment \\7ith steroids or cromolyn is known to reduce the diagnostic sensitivity of peak flo\vmeters. 4 It makes much more sense for the diagnosing physician to perform the peak flo\\' measurements. The patient is typically still working and has not yet been treated, and the physician can take the patient off work for the extended time needed to have the testing performed. State health departments have an important role once the physician has diagnosed a case ofoccupational asthma. Governmental investigators can remove more of the uncertainty in the diagnosis by identifying the exposures of the patient, both qualitatively and quantitatively. Occupational asthma is a dose-related condition. The higher the levels of exposure, the larger the percentage of exposed individuals \vho \vill become symptomatic. As is the case \\7ith communicable disease, physicians have a public health responsibility to \\Turk with their state health departments. Followup of plants \vhere index patients have \vorked identifies additional symptomatic individuals in need of medical care and facilities in need of better workplace controls. Seven states currently are funded by the National Institute of Occupational Safety and Health to assist physicians in the dia~nosis of occupational asthtna and to facilitate \\7orkplace fullo\\r-ups.6 There has been insufficient work to determine in \\That percentage of adult asthmatic persons the cause of their asthma is a workplace exposure. Surveys in Italy in the 1950s attributed 2 percent.'i and surveys in the 1970s in Japan attributed 15 percent of them to work exposure. k Fifteen percent of patients \vith asthma \\7ho had applied for Social Security disability
"A can of worms," That's how a pulmonologist
recently summarized to me his experience in diagnosing occupational asthma. An apt summary for a condition that has definite economic and legal consequences, and yet the physician may feel uncertain about the diagnosis. What can physicians do to feel more confident in their diagnosis of occupational asthma? First, does the patient actually have asthma? Given the kno\\'n disagreernent between a clinician's diagnosis ofasthma and laboratory findings of variable airflow obstruction, an objective nleasurement ofairway hyperresponsiveness is important.) Second, is the asthma related to \vork? The mainstay in suspecting that a patient's asthma is secondary to an allergen at work is a history that indicates the onset of symptoms after some minimal sensitization period and improvernent with absence of exposure. Given the fact that the patient olay have early, late, dual, or recurrent late onset of syolph>OlS after a single exposure, the temporal association may not be obvious. Given repeated exposure, the temporal association \vith \\7ork may become even less obvious. The patient rnay no\v react to nonspecific irritants outside of work, such as cold or cigarette smoke, and may continue to have symptorns for years after leaving \\Tork. 2 An objective rneasure is important to document a change in airflo\\' obstruction in relation to \vork. Bronchoprovocation testing \vith the specific antigen is I10t clinically available. Spirometry performed before and after \vork or before or after a vacation or a sick leave that sho\\7s a significant change in airflo\v is useful. H(}\vever, given the varied time periods after exposure when a patient olay react, the absence of a significant change may be a false-negative result. An article by Henneberger et al in this issue (see page 1515) delnonstrates the usefulness of using a peak flowmeter to document an association between \vork and the patient's respiratory symptoms. This approach has been used successfully mainly by investigators in England. 3 With repeated use of the peak flowmeter every 2 h, both at work and away from work, changes in airflow can be measured over a longer period than with pre- and poshvork spirometry. This approach is more sensitive than pre- and postshift spirometry.4 The data in the article by Henneberger et al also illustrate the current state of practice in the
CHEST I 100 I 6 I DECEMBER. 1991
1481
in the United States responded that their asthma was caused by work. 9 Over 200 substances are known workplace allergens, and new substances are being reported each year. 10 Surveys in particular companies have found that the prevalence ofoccupational asthma ranges from 5 percent to 20 percent. More awareness of this condition by practitioners is needed. The tools for diagnosing occupational asthma are readily available. Our ability to turn that can of worms" into fish will depend on how well we use existing objective diagnostic procedures and public health resources in our clinical practice. Kenneth D. Rosenman, M. D. East lansing, Michigan U
Associate Professor of Medicine, College of Human Medicine, Michigan State University, East Lansing. Hqrint t'8quests: Dr. Rosenman, Michigan State University, 8338 CUnical Center, East Lansing 48824-1317
REFERENCES 1 Adelroth E, Hargreave FE, Ramsdale EH. Do physicians need objective measurements to diagnose asthma? Am Rev Respir Dis 1986; 134:704-07 2 Allard C, Cartier A, Ghezzo H, Malo JL. Occupational asthma due to various agents: absence ofclinical and functional improvement at an interval of four or more years after cessation of exposure. Chest 1989; 96:1046-49 3 Burge PS. Problems in the diagnosis of occupational asthma. Br J Dis Chest 1987; 81:105-15 4 Burge PS. Single and serial measurements of lung function in the diagnosis of occupational asthma. Eur J Respir Dis 1982; 63(supply 123):47-59 5 Klees JE, Alexander M, Hempel D, Beckett ~ Rubin R, Barnhart S, et al. Evaluation of a proposed NIOSH surveillance case definition for occupational asthma. Chest 1990; 98(suppl): 2l2S-ISS 6 Matte TO, Hoffman RE, Rosenman KD, Stanbury M. Surveillance of occupational asthma under the SENSOR model. Chest 1990; 98(suppl):173S-78S 7 Salvaggio J, 00. Occupational and environmental respiratory disease in NIAID task force report: asthma and other allergic disease. NIH publication 79-387. Washington, DC: US Department of Health Education and Welfare, 1979 8 Kobayashi S. Different aspects of occupational asthma in Japan. In: Frazier CA, ed. Occupational asthma. New York: Van Nostrand Reinhold, 1980; 229-44 9 Blanc E Occupational asthma ini a national disability surve~ Chest 1987; 92:613-17 10 Chan-Yeung M, Lam S. State of the art: occupational asthma. Am Rev Respir Dis 1986; 133:686-703
Radiographic Abnormalities In Vermont Granite Workers Exposed to Low Levels of Granite Dust The report in this issue by Graham and co-workers (see page 1507) is the most recent in a series of epidemiologic studies of workers exposed to silica in the Vermont granite industry. Early studies found appallingly high rates of silicosis and tuberculosis. 1,2 Dust controls were introduced into this industry in 1482
1938. By 1940, levels averaged approximately 5 million particles per cubic foot (mppcf) with only about 10 percent of the samples exceeding the average, mainly in quarries where wet drilling was not yet practiced. 3 In the reports since 1940, it appears that the dust levels averaged less than the current standard of 100 micrograms/cubic meter of respirable dust (roughly equivalent to 10 mppcf since granite dust on average contains 9 to 11 percent quartz). Throughout these studies there has been a steady decline in the prevalence of radiographic changes consistent with silicosis. This is certainly encouraging and appears to validate the implementation of dust control measures. Indeed, this body of work has become extremely important to the health of workers with silica exposure worldwide because the studies reported from this population form the backbone of the currently mandated Occupational Safety and Health Administration silica exposure limits. The central question addressed by Graham and coworkers relates to the effectiveness of the dust control program. Having achieved dust levels protective of the vast majority of exposed workers, they found a chest radiographic appearance not usually associated with silicosis. The classic radiographic appearance of silicosis is that of small rounded opacities." In this study, Graham and co-workers found 0.7 percent of 972 chest radiographs that showed these opacities of profusion category 1/0 or greater. In contrast, they found 2.8 percent of chest radiographs that showed irregular opacities of profusion category 1/0 or higher. Further, the rounded opacities tended to occur in the upper zones, the typical site of silicotic nodules, whereas the irregular opacities tended to occur in the lower zones. On the basis of the prevalence of rounded opacities (classic changes of silicosis), Graham et al concluded that exposure to quartz under the current standard has "essentially eliminated definite radiographic changes of silicosis." The question remains as to the significance of irregular opacities in these workers. Workers demonstrating irregular opacities were older, had smoked more, and had longer occupational exposure to granite dust than the work force as a whole. Anecdotal examples of men with irregular opacities, who had worked the major portion of their lives in a setting where silicosis was not expected, were cited. The authors also noted that in a previous study of this population, a relationship existed between irregular opacities and smoking. 5 Concerns about smoking and dust exposure were addressed among coal miners when data from the first round of the National Coal Study were analyzed for type of radiographic opacity.6 Rounded opacities occurred. more frequently among nonsmoking than smoking coal miners independent of years under-
CHEST editorials
------
VOLUME 100 I NUMBER 6 I DECEMBER, 1991
Asthma and Work: How Do You Diagnose the Association?
diagnosis of occupational asthrna. Only one of the 57 patients reported to the Ne\\r Jersey Health Department had heen evaluated by his or her private physician with pulmonary function testing in relation to \\Tork. In another study,5 17 (17 percent) of 101 occupational asthma patients from four occupational medicine clinics had undergone puhnonary testing in relation to \vork. In the article by Henneberger et aI, the peak flo\vs \vere measured by the state health department. This is a very impractical approach. Most patients could not be tested with peak flowmeters because the physician had not reported the patient's name, the patient was no longer working, or the patient \\7as unable to be away from work for the recomrnended hvo \\7eeks. Additionally, the patients were already being treated by the tiole they \\Tere referred to the state health department. Treatment \\7ith steroids or cromolyn is known to reduce the diagnostic sensitivity of peak flo\vmeters. 4 It makes much more sense for the diagnosing physician to perform the peak flo\\' measurements. The patient is typically still working and has not yet been treated, and the physician can take the patient off work for the extended time needed to have the testing performed. State health departments have an important role once the physician has diagnosed a case ofoccupational asthma. Governmental investigators can remove more of the uncertainty in the diagnosis by identifying the exposures of the patient, both qualitatively and quantitatively. Occupational asthma is a dose-related condition. The higher the levels of exposure, the larger the percentage of exposed individuals \vho \vill become symptomatic. As is the case \\7ith communicable disease, physicians have a public health responsibility to \\Turk with their state health departments. Followup of plants \vhere index patients have \vorked identifies additional symptomatic individuals in need of medical care and facilities in need of better workplace controls. Seven states currently are funded by the National Institute of Occupational Safety and Health to assist physicians in the dia~nosis of occupational asthtna and to facilitate \\7orkplace fullo\\r-ups.6 There has been insufficient work to determine in \\That percentage of adult asthmatic persons the cause of their asthma is a workplace exposure. Surveys in Italy in the 1950s attributed 2 percent.'i and surveys in the 1970s in Japan attributed 15 percent of them to work exposure. k Fifteen percent of patients \vith asthma \\7ho had applied for Social Security disability
"A can of worms," That's how a pulmonologist
recently summarized to me his experience in diagnosing occupational asthma. An apt summary for a condition that has definite economic and legal consequences, and yet the physician may feel uncertain about the diagnosis. What can physicians do to feel more confident in their diagnosis of occupational asthma? First, does the patient actually have asthma? Given the kno\\'n disagreernent between a clinician's diagnosis ofasthma and laboratory findings of variable airflow obstruction, an objective nleasurement ofairway hyperresponsiveness is important.) Second, is the asthma related to \vork? The mainstay in suspecting that a patient's asthma is secondary to an allergen at work is a history that indicates the onset of symptoms after some minimal sensitization period and improvernent with absence of exposure. Given the fact that the patient olay have early, late, dual, or recurrent late onset of syolph>OlS after a single exposure, the temporal association may not be obvious. Given repeated exposure, the temporal association \vith \\7ork may become even less obvious. The patient rnay no\v react to nonspecific irritants outside of work, such as cold or cigarette smoke, and may continue to have symptorns for years after leaving \\Tork. 2 An objective rneasure is important to document a change in airflo\\' obstruction in relation to \vork. Bronchoprovocation testing \vith the specific antigen is I10t clinically available. Spirometry performed before and after \vork or before or after a vacation or a sick leave that sho\\7s a significant change in airflo\v is useful. H(}\vever, given the varied time periods after exposure when a patient olay react, the absence of a significant change may be a false-negative result. An article by Henneberger et al in this issue (see page 1515) delnonstrates the usefulness of using a peak flowmeter to document an association between \vork and the patient's respiratory symptoms. This approach has been used successfully mainly by investigators in England. 3 With repeated use of the peak flowmeter every 2 h, both at work and away from work, changes in airflow can be measured over a longer period than with pre- and poshvork spirometry. This approach is more sensitive than pre- and postshift spirometry.4 The data in the article by Henneberger et al also illustrate the current state of practice in the
CHEST I 100 I 6 I DECEMBER. 1991
1481
in the United States responded that their asthma was caused by work. 9 Over 200 substances are known workplace allergens, and new substances are being reported each year. 10 Surveys in particular companies have found that the prevalence ofoccupational asthma ranges from 5 percent to 20 percent. More awareness of this condition by practitioners is needed. The tools for diagnosing occupational asthma are readily available. Our ability to turn that can of worms" into fish will depend on how well we use existing objective diagnostic procedures and public health resources in our clinical practice. Kenneth D. Rosenman, M. D. East lansing, Michigan U
Associate Professor of Medicine, College of Human Medicine, Michigan State University, East Lansing. Hqrint t'8quests: Dr. Rosenman, Michigan State University, 8338 CUnical Center, East Lansing 48824-1317
REFERENCES 1 Adelroth E, Hargreave FE, Ramsdale EH. Do physicians need objective measurements to diagnose asthma? Am Rev Respir Dis 1986; 134:704-07 2 Allard C, Cartier A, Ghezzo H, Malo JL. Occupational asthma due to various agents: absence ofclinical and functional improvement at an interval of four or more years after cessation of exposure. Chest 1989; 96:1046-49 3 Burge PS. Problems in the diagnosis of occupational asthma. Br J Dis Chest 1987; 81:105-15 4 Burge PS. Single and serial measurements of lung function in the diagnosis of occupational asthma. Eur J Respir Dis 1982; 63(supply 123):47-59 5 Klees JE, Alexander M, Hempel D, Beckett ~ Rubin R, Barnhart S, et al. Evaluation of a proposed NIOSH surveillance case definition for occupational asthma. Chest 1990; 98(suppl): 2l2S-ISS 6 Matte TO, Hoffman RE, Rosenman KD, Stanbury M. Surveillance of occupational asthma under the SENSOR model. Chest 1990; 98(suppl):173S-78S 7 Salvaggio J, 00. Occupational and environmental respiratory disease in NIAID task force report: asthma and other allergic disease. NIH publication 79-387. Washington, DC: US Department of Health Education and Welfare, 1979 8 Kobayashi S. Different aspects of occupational asthma in Japan. In: Frazier CA, ed. Occupational asthma. New York: Van Nostrand Reinhold, 1980; 229-44 9 Blanc E Occupational asthma ini a national disability surve~ Chest 1987; 92:613-17 10 Chan-Yeung M, Lam S. State of the art: occupational asthma. Am Rev Respir Dis 1986; 133:686-703
Radiographic Abnormalities In Vermont Granite Workers Exposed to Low Levels of Granite Dust The report in this issue by Graham and co-workers (see page 1507) is the most recent in a series of epidemiologic studies of workers exposed to silica in the Vermont granite industry. Early studies found appallingly high rates of silicosis and tuberculosis. 1,2 Dust controls were introduced into this industry in 1482
1938. By 1940, levels averaged approximately 5 million particles per cubic foot (mppcf) with only about 10 percent of the samples exceeding the average, mainly in quarries where wet drilling was not yet practiced. 3 In the reports since 1940, it appears that the dust levels averaged less than the current standard of 100 micrograms/cubic meter of respirable dust (roughly equivalent to 10 mppcf since granite dust on average contains 9 to 11 percent quartz). Throughout these studies there has been a steady decline in the prevalence of radiographic changes consistent with silicosis. This is certainly encouraging and appears to validate the implementation of dust control measures. Indeed, this body of work has become extremely important to the health of workers with silica exposure worldwide because the studies reported from this population form the backbone of the currently mandated Occupational Safety and Health Administration silica exposure limits. The central question addressed by Graham and coworkers relates to the effectiveness of the dust control program. Having achieved dust levels protective of the vast majority of exposed workers, they found a chest radiographic appearance not usually associated with silicosis. The classic radiographic appearance of silicosis is that of small rounded opacities." In this study, Graham and co-workers found 0.7 percent of 972 chest radiographs that showed these opacities of profusion category 1/0 or greater. In contrast, they found 2.8 percent of chest radiographs that showed irregular opacities of profusion category 1/0 or higher. Further, the rounded opacities tended to occur in the upper zones, the typical site of silicotic nodules, whereas the irregular opacities tended to occur in the lower zones. On the basis of the prevalence of rounded opacities (classic changes of silicosis), Graham et al concluded that exposure to quartz under the current standard has "essentially eliminated definite radiographic changes of silicosis." The question remains as to the significance of irregular opacities in these workers. Workers demonstrating irregular opacities were older, had smoked more, and had longer occupational exposure to granite dust than the work force as a whole. Anecdotal examples of men with irregular opacities, who had worked the major portion of their lives in a setting where silicosis was not expected, were cited. The authors also noted that in a previous study of this population, a relationship existed between irregular opacities and smoking. 5 Concerns about smoking and dust exposure were addressed among coal miners when data from the first round of the National Coal Study were analyzed for type of radiographic opacity.6 Rounded opacities occurred. more frequently among nonsmoking than smoking coal miners independent of years under-
