To the Editor: The epidemiologic analysis of deaths in Chinaby He et al. (Sept. 15 issue)1 suggests a change in patterntoward that in Western societies: heart disease, cancer, andcerebrovascular disease are now listed as the top three causesof death. However, respiratory diseases are clearly underrepresentedin their report, because of the way the causes of death wereclassified. The conclusions of the authors may perpetuate thechronic underrecognition of lung diseases and lessen the pressureon governments to promote their prevention and management. Simplyacknowledging (in the legend to Figure 1 of the article) that"chronic pulmonary heart disease . . . is usuallycaused by chronic obstructive pulmonary disease [COPD]" is insufficient.Those who read the article will focus on heart disease, cancer,and stroke, because these are what the authors conclude arethe major causes of death.
We challenge the authors to reanalyze their data and presenttotal mortality from COPD, asthma, pulmonary infections (includingtuberculosis), other less common lung diseases, and lung cancer(because of its close relationship to smoking and COPD). Webelieve that, if the causes of death were properly classified,a picture would emerge showing that lung diseases as definedhere are at least as important a public health target as heartdisease, cancer, and stroke.
Peter D. Wagner, M.D. American Thoracic Society New York, NY 10006 pdwagner{at}ucsd.edu
Giovanni Viegi, M.D. European Respiratory Society 1003 Lausanne, Switzerland
Carlos M. Luna, M.D. Asociación Latinoamericana del Tórax 1828 Buenos Aires, Argentina
Yoshinosuke Fukuchi, M.D. Asian Pacific Society of Respirology Tokyo 113-0033, Japan
Paul A. Kvale, M.D. American College of Chest Physicians Northbrook, IL 60062
Asma El Sony, M.D., Ph.D. International Union against Tuberculosis and Lung Disease 75006 Paris, France
References
He J, Gu D, Wu X, et al. Major causes of death among men and women in China. N Engl J Med 2005;353:1124-1134. [Free Full Text]
To the Editor: In the study by He et al., overweight or obesity, as compared with normal weight, was not associated with increasedmortality. This finding is inconsistent with the growing literatureindicating that obesity is a major risk factor for cardiovasculardiseases, type 2 diabetes, stroke, and certain types of canceras well as death from all causes. However, other data indicatethat obesity is positively related to socioeconomic status inChina.1 Higher socioeconomic status is associated with betteraccess to health care, better nutrition, and less depression.Low socioeconomic status is well known to be a powerful predictorof all-cause mortality, as shown in many previous studies.2,3Further analysis of the associations among socioeconomic status,obesity, and mortality in the data of He et al. may clarifythis issue.
Ming Wei, M.D. Kun Wang, M.D. 9 Columbia Dr. Camp Hill, PA 17011
References
Xu F, Yin XM, Zhang M, Leslie E, Ware R, Owen N. Family average income and body mass index above the healthy weight range among urban and rural residents in regional Mainland China. Public Health Nutr 2005;8:47-51. [Medline]
Lynch JW, Kaplan GA, Cohen RD, et al. Childhood and adult socioeconomic status as predictors of mortality in Finland. Lancet 1994;343:524-527. [CrossRef][Web of Science][Medline]
Wei M, Valdez RA, Mitchell BD, Haffner SM, Stern MP, Hazuda HP. Migration status, socioeconomic status, and mortality rates in Mexican Americans and non-Hispanic whites: the San Antonio Heart Study. Ann Epidemiol 1996;6:307-313. [CrossRef][Web of Science][Medline]
To the Editor: He and colleagues assessed physical activityby categorizing the physical labor involved in a participant'swork. Other data indicate that other types of physical activityare important to consider with regard to Chinese persons. First,in other studies, cycling and a combination of walking and ridingbuses were the most common means of transportation, and lessthan 10 percent of adults reported an absence of physical activityduring commuting in urban China.1,2 Second, housework, as oneof the daily physical activities of adult women, accounted for50 percent of the overall physical activity among adult women.3Third, traditional Chinese tai chi, or morning exercises, wascommonly practiced by many Chinese adults and elderly persons.4Previous studies in China showed no reduction in the risk ofcardiovascular disease in association with heavy physical activityrelated to occupation, whereas the risk of colon cancer wasinversely related to commuting-related physical activities andmortality was reduced with greater leisure-time physical activity.1,2,3,4
Bin Wang, Ph.D. Nanjing Medical University Nanjing 210029, China binwang{at}njmu.edu.cn
References
Hu G, Pekkarinen H, Hanninen O, et al. Physical activity during leisure and commuting in Tianjin, China. Bull World Health Organ 2002;80:933-938. [Medline]
Hou L, Ji BT, Blair A, Dai Q, Gao YT, Chow WH. Commuting physical activity and risk of colon cancer in Shanghai, China. Am J Epidemiol 2004;160:860-867. [Free Full Text]
Ma J, Liu Z, Ling W. Physical activity, diet and cardiovascular disease risks in Chinese women. Public Health Nutr 2003;6:139-146. [Medline]
Lam TH, Ho SY, Hedley AJ, Mak KH, Leung GM. Leisure time physical activity and mortality in Hong Kong: case-control study of all adult deaths in 1998. Ann Epidemiol 2004;14:391-398. [CrossRef][Web of Science][Medline]
To the Editor: The analysis of mortality in China by He andcolleagues includes more than 1000 deaths per 100,000 person-yearsin China due to respiratory causes (infections and COPD). Thesole risk factor for respiratory illness that they examinedwas a history of cigarette smoking (defined as smoking at leastone cigarette per day for one or more years). Solid-fuel usehas been linked to respiratory diseases, including COPD, andin the case of coal, to lung cancer.1 In Guangdong province,a recent survey showed that only 10.9 percent of women withCOPD had ever smoked, but solid-fuel use was a significant riskfactor.2
The World Health Organization has estimated that 80 percentof Chinese households use biomass fuel, with coal used in 31percent of households. The attributable mortality of solid-fueluse in the Western Pacific region (primarily China) has beenestimated to be more than half a million lives.3 Exposure tosolid-fuel use is an important preventable contributor to mortalitythat was not addressed in an otherwise fine study. The limitationof exposure to biomass combustion should be added to the listof preventive measures.
V. Theodore Barnett, M.D. Medical College of Wisconsin Milwaukee, WI 53226 tbarnett{at}mail.mcw.edu
References
Bruce N, Perez-Padilla R, Albalak R. The health effects of indoor air pollution exposure in developing countries. Geneva: World Health Organization, 2002. (WHO/SDE/OEH/02.05.)
Liu SM, Wang XP, Wang DL, et al. Epidemiologic analysis of COPD in Guangdong Province. Zhonghua Yi Xue Za Zhi 2005;85:747-752. [Medline]
Desai MA, Mehta S, Smith KR. Indoor smoke from solid fuels: assessing the environmental burden of disease at national and local levels. WHO environmental burden of disease series. No. 4. Geneva: World Health Organization, 2004.
The authors reply: Wagner and colleagues correctly point outthat chronic pulmonary heart disease can be classified as eitherrespiratory disease or cardiovascular disease. In our study,the causes of death were coded according to the InternationalClassification of Diseases, 9th Revision (ICD-9).1 Respiratorydisease would be a leading cause of death in China if chronicpulmonary heart disease were included in that category (Table 1).Dr. Barnett suggests that solid-fuel use is an importantrisk factor for COPD, besides cigarette smoking, in China. Unfortunately,data on solid-fuel use were not collected in our study.
Table 1. Age-Standardized Mortality Associated with Respiratory Disease.
As indicated by Drs. Wei and K. Wang, socioeconomic status andaccess to health care are important potential confounders ofthe association between body-mass index and mortality from allcauses. In addition, hypertension and diabetes are key intermediatefactors in the causal pathway between body-mass index and mortality.2Without adjustment for hypertension and diabetes, we found thatobesity was associated with increased mortality from all causes(relative risk of death, 1.20; 95 percent confidence interval,1.08 to 1.30) among urban residents but not among rural residents(relative risk, 0.90, 95 percent confidence interval, 0.73 to1.19). In our study, only work-related physical activity wasmeasured at the baseline examination. We agree with Dr. B. Wangthat other forms of physical activity are important in China.Lack of data on leisure-time physical activity was identifiedas a limitation of our study.
Jiang He, M.D., Ph.D. Tulane University New Orleans, LA 70112 jhe{at}tulane.edu
Dongfeng Gu, M.D. Chinese Academy of Medical Sciences Beijing 100037, China
Paul K. Whelton, M.D. Tulane University New Orleans, LA 70112
References
International classification of diseases, 9th rev., clinical modification: ICD-9-CM. Los Angles: Practice Management Information Corporation, 1998.
Manson JE, Willett WC, Stampfer MJ, et al. Body weight and mortality among women. N Engl J Med 1995;333:677-685. [Free Full Text]
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(2006). Myeloperoxidase G-463A polymorphism and the risk of gastric cancer: a case-control study. Carcinogenesis
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