Factors associated with difference in prevalence of asthma in children from three cities in China: multicentre epidemiological survey
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《英国医生杂志》
1 Department of Paediatrics, Chinese University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China, 2 Department of Medicine and Therapeutics, Chinese University of Hong Kong, 3 University Children's Hospital, Munich, Germany, 4 Guangzhou Institute of Respiratory Disease, Guangzhou, People's Republic of China, 5 Clinical and Education Centre for Asthma, Capital Institute of Paediatrics, Beijing, People's Republic of China
Correspondence to: G W K Wong wingkinwong@cuhk.edu.hk
Abstract
Asthma is one of the most common chronic disorders in children, and its prevalence varies worldwide.1 Consistent reports from different countries indicate an increase in prevalence of asthma and allergies.2-6 This increasing trend is unlikely to be explained by genetic factors. Despite numerous studies in different communities, the factors related to the increasing prevalence of asthma are largely unknown, probably because the factors are so widespread that it is difficult for epidemiological studies to identify them.
In China the prevalence of asthma seems to be lower than in the West,1 and within China the prevalence varies between regions—for example, over one year, 12.4% and 10.1% of children aged 13 and 14 years in Hong Kong had wheeze compared with 4.2% and 2.0% of children in mainland China.7 As children from these regions have a similar genetic background, it may be possible to determine the environmental factors associated with asthma.
The international study of asthma and allergies in childhood phase II study was designed to assess the prevalence of objective markers of atopic diseases and to investigate the association with lifestyle and environmental factors.8 Using this protocol, we compared the environmental and lifestyle factors related to asthma in children from Hong Kong and "mainland China" (areas of China not in the special administrative region of Hong Kong).
Methods
Overall, 10 902 children took part in the survey, of whom 3483 underwent a skin prick test. Table 1 summarises the prevalence of asthma symptoms and atopic sensitisation in the three study populations. The prevalence of wheeze in the past year was significantly higher in children from Hong Kong (odds ratio 1.64, 95% confidence interval 1.35 to 1.99). Other symptoms, including speech limiting wheeze and exercise induced wheeze, were also significantly more common in children from Hong Kong. Factors significantly associated with being a child living on the mainland were age, school grade, parents' level of education, parental history of rhinitis and eczema, history of sharing a bedroom, smoking in the home, parents' birth place, and presence of older siblings. After adjustment for the propensity score, six factors were related to current wheeze: cooking with gas, foam pillows, cotton quilts, damp housing, consumption of fruit more than once a day, and consumption of raw vegetables once or more a week (table 2). Foam pillows and cooking with gas were associated with the highest risk for current wheeze; protective factors were cotton quilts, consumption of fruit more than once a day, and consumption of raw vegetables at least once a week.
Table 1 Prevalence of asthma symptoms and atopic sensitisation in schoolchildren from three cities in China
Table 2 Associations of environmental and dietary exposure factors and current wheeze in Chinese schoolchildren, adjusted for mainland propensity score (see text) and sex
After adjustment for the propensity score and sex, factors that remained significantly associated with current wheeze were cooking with gas, foam pillows, damp housing, and consumption of fruit. The association between cotton quilts and current wheeze was of borderline significance.
Living on the mainland was associated with a significantly reduced risk of current wheeze (odds ratio 0.61, 95% confidence interval 0.49 to 0.77; table 3). With the sequential addition to the logistic regression model of the six factors identified as protecting mainland children against current wheeze along with adjustment for the propensity score and sex, the odds ratios gradually increased from 0.61 to 0.99.
Table 3 Regression analysis to determine protective effect of living on mainland China and risk of current wheeze in relation to environmental factors and diet
Discussion
International Study of Asthma and Allergies in Childhood (ISAAC) Steering Committee. Worldwide variation in prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema. Lancet 1998;351: 1125-32.
Hsieh KH, Shen JJ. Prevalence of childhood asthma in Taipei, Taiwan and other Asian Pacific countries. J Asthma 1988;25: 73-82.
Aberg N, Hesselmar B, Aberg B, Eriksson B. Increase of asthma, allergic rhinitis and eczema in Swedish schoolchildren between 1979 and 1991. Clin Exp Allergy 1995;25: 815-9.
Burr ML, Butland BK, King S, Vaughan-Williams E. Changes in asthma prevalence: two surveys 15 years apart. Arch Dis Child 1989;64: 1118-25.
Goren AI, Hellmann S. Changing prevalence of asthma among schoolchildren in Israel. Eur Respir J 1997;10: 2279-84.
Shaw RA, Crane J, O'Donnell TV, Porteous LE, Coleman ED. Increasing asthma prevalence in a rural New Zealand adolescent population, 1975-89. Arch Dis Child 1990;65: 1319-23.
Leung R, Wong G, Lau J, Ho A, Chan JK, Choy D, et al. Prevalence of asthma and allergy in Hong Kong schoolchildren: an ISAAC study. Eur Respir J 1997;10: 354-60.
International study of asthma and allergies inchildhood. isaac.auckland.ac.nz/Phasetwo/Modules/ModFrame.html (accessed 14 Aug 2004).
Wong GWK, Hui DSC, Chan HH, Fok TF, Leung R, Zhong NS, et al. Prevalence of respiratory and atopic disorders in Chinese schoolchildren. Clin Exp Allergy 2001;31: 1225-31.
Wong GW, Li ST, Hui DS, Fok TF, Zhong NS, Chen YZ, et al. Individual allergens as risk factors for asthma and bronchial hyperresponsiveness in Chinese children. Eur Respir J 2002;19: 288-93.
D'Agostino RB Jr. Propensity score methods for bias reduction in the comparison of a treatment to a non-randomized control group. Stat Med 1998;17: 2265-81.
Greenland S. In: Rothman KJ, Greenland S, eds. Modern epidemiology. 2nd ed. New York: Lippincott, Williams, Wilkins, 1998.
Pearce N, Pekkanen J, Beasley R. How much asthma is really attributable to atopy? Thorax 1999;54: 268-72.
Dekker C, Dales R, Bartlett S, Brunekreef B, Zwanenburg H. Childhood asthma and the indoor environment. Chest 1991;100: 922-6.
Jarvis D, Chinn S, Luczynska C, Burney P. Association of respiratory symptoms and lung function in young adults with use of domestic gas appliances. Lancet 1996;347: 426-31.
Burr ML, Anderson HR, Austin JB, Harkins LS, Kaur B, Strachan DP, et al. Respiratory symptoms and home environment in children: a national survey. Thorax 1999;54: 27-32.
Ponsonby AL, Dwyer T, Kemp A, Couper D, Cochrane J, Carmichael A. A prospective study of the association between home gas appliance use during infancy and subsequent dust mite sensitization and lung function in childhood. Clin Exp Allergy 2001;31: 1544-52.
Strachan DP, Carey IM. Home environment and severe asthma in adolescence: a population based case-control study. BMJ 1995;311: 1053-6.
Strachan DP, Carey IM. Reduced risk of wheezing in children using feather pillows is confirmed. BMJ 1997;314: 518.
Andrae S, Axelson O, Bjorksten B, Fredriksson M, Kjellman NI. Symptoms of bronchial hyperreactivity and asthma in relation to environmental factors. Arch Dis Child 1988;63: 473-8.
Brunekreef B, Dockery DW, Speizer FE, Ware JH, Spengler JD, Ferris BG. Home dampness and respiratory morbidity in children. Am Rev Respir Dis 1989;140: 1363-7.
Williamson IJ, Martin CJ, McGill G, Monie RD, Fennerty AG. Damp housing and asthma: a case-control study. Thorax 1997;52: 229-34.
Shaheen SO, Sterne JA, Thompson RL, Songhurst CE, Margetts BM, Burney PG. Dietary antioxidants and asthma in adults: population-based case-control study. Am J Respir Crit Care Med 2001;164: 1823-8.
Woods RK, Walters EH, Raven JM, Wolfe R, Ireland PD, Thien FC, et al. Food and nutrient intakes and asthma risk in young adults. Am J Clin Nutr 2003;78: 414-21.(Gary W K Wong, professor1)
Correspondence to: G W K Wong wingkinwong@cuhk.edu.hk
Abstract
Asthma is one of the most common chronic disorders in children, and its prevalence varies worldwide.1 Consistent reports from different countries indicate an increase in prevalence of asthma and allergies.2-6 This increasing trend is unlikely to be explained by genetic factors. Despite numerous studies in different communities, the factors related to the increasing prevalence of asthma are largely unknown, probably because the factors are so widespread that it is difficult for epidemiological studies to identify them.
In China the prevalence of asthma seems to be lower than in the West,1 and within China the prevalence varies between regions—for example, over one year, 12.4% and 10.1% of children aged 13 and 14 years in Hong Kong had wheeze compared with 4.2% and 2.0% of children in mainland China.7 As children from these regions have a similar genetic background, it may be possible to determine the environmental factors associated with asthma.
The international study of asthma and allergies in childhood phase II study was designed to assess the prevalence of objective markers of atopic diseases and to investigate the association with lifestyle and environmental factors.8 Using this protocol, we compared the environmental and lifestyle factors related to asthma in children from Hong Kong and "mainland China" (areas of China not in the special administrative region of Hong Kong).
Methods
Overall, 10 902 children took part in the survey, of whom 3483 underwent a skin prick test. Table 1 summarises the prevalence of asthma symptoms and atopic sensitisation in the three study populations. The prevalence of wheeze in the past year was significantly higher in children from Hong Kong (odds ratio 1.64, 95% confidence interval 1.35 to 1.99). Other symptoms, including speech limiting wheeze and exercise induced wheeze, were also significantly more common in children from Hong Kong. Factors significantly associated with being a child living on the mainland were age, school grade, parents' level of education, parental history of rhinitis and eczema, history of sharing a bedroom, smoking in the home, parents' birth place, and presence of older siblings. After adjustment for the propensity score, six factors were related to current wheeze: cooking with gas, foam pillows, cotton quilts, damp housing, consumption of fruit more than once a day, and consumption of raw vegetables once or more a week (table 2). Foam pillows and cooking with gas were associated with the highest risk for current wheeze; protective factors were cotton quilts, consumption of fruit more than once a day, and consumption of raw vegetables at least once a week.
Table 1 Prevalence of asthma symptoms and atopic sensitisation in schoolchildren from three cities in China
Table 2 Associations of environmental and dietary exposure factors and current wheeze in Chinese schoolchildren, adjusted for mainland propensity score (see text) and sex
After adjustment for the propensity score and sex, factors that remained significantly associated with current wheeze were cooking with gas, foam pillows, damp housing, and consumption of fruit. The association between cotton quilts and current wheeze was of borderline significance.
Living on the mainland was associated with a significantly reduced risk of current wheeze (odds ratio 0.61, 95% confidence interval 0.49 to 0.77; table 3). With the sequential addition to the logistic regression model of the six factors identified as protecting mainland children against current wheeze along with adjustment for the propensity score and sex, the odds ratios gradually increased from 0.61 to 0.99.
Table 3 Regression analysis to determine protective effect of living on mainland China and risk of current wheeze in relation to environmental factors and diet
Discussion
International Study of Asthma and Allergies in Childhood (ISAAC) Steering Committee. Worldwide variation in prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema. Lancet 1998;351: 1125-32.
Hsieh KH, Shen JJ. Prevalence of childhood asthma in Taipei, Taiwan and other Asian Pacific countries. J Asthma 1988;25: 73-82.
Aberg N, Hesselmar B, Aberg B, Eriksson B. Increase of asthma, allergic rhinitis and eczema in Swedish schoolchildren between 1979 and 1991. Clin Exp Allergy 1995;25: 815-9.
Burr ML, Butland BK, King S, Vaughan-Williams E. Changes in asthma prevalence: two surveys 15 years apart. Arch Dis Child 1989;64: 1118-25.
Goren AI, Hellmann S. Changing prevalence of asthma among schoolchildren in Israel. Eur Respir J 1997;10: 2279-84.
Shaw RA, Crane J, O'Donnell TV, Porteous LE, Coleman ED. Increasing asthma prevalence in a rural New Zealand adolescent population, 1975-89. Arch Dis Child 1990;65: 1319-23.
Leung R, Wong G, Lau J, Ho A, Chan JK, Choy D, et al. Prevalence of asthma and allergy in Hong Kong schoolchildren: an ISAAC study. Eur Respir J 1997;10: 354-60.
International study of asthma and allergies inchildhood. isaac.auckland.ac.nz/Phasetwo/Modules/ModFrame.html (accessed 14 Aug 2004).
Wong GWK, Hui DSC, Chan HH, Fok TF, Leung R, Zhong NS, et al. Prevalence of respiratory and atopic disorders in Chinese schoolchildren. Clin Exp Allergy 2001;31: 1225-31.
Wong GW, Li ST, Hui DS, Fok TF, Zhong NS, Chen YZ, et al. Individual allergens as risk factors for asthma and bronchial hyperresponsiveness in Chinese children. Eur Respir J 2002;19: 288-93.
D'Agostino RB Jr. Propensity score methods for bias reduction in the comparison of a treatment to a non-randomized control group. Stat Med 1998;17: 2265-81.
Greenland S. In: Rothman KJ, Greenland S, eds. Modern epidemiology. 2nd ed. New York: Lippincott, Williams, Wilkins, 1998.
Pearce N, Pekkanen J, Beasley R. How much asthma is really attributable to atopy? Thorax 1999;54: 268-72.
Dekker C, Dales R, Bartlett S, Brunekreef B, Zwanenburg H. Childhood asthma and the indoor environment. Chest 1991;100: 922-6.
Jarvis D, Chinn S, Luczynska C, Burney P. Association of respiratory symptoms and lung function in young adults with use of domestic gas appliances. Lancet 1996;347: 426-31.
Burr ML, Anderson HR, Austin JB, Harkins LS, Kaur B, Strachan DP, et al. Respiratory symptoms and home environment in children: a national survey. Thorax 1999;54: 27-32.
Ponsonby AL, Dwyer T, Kemp A, Couper D, Cochrane J, Carmichael A. A prospective study of the association between home gas appliance use during infancy and subsequent dust mite sensitization and lung function in childhood. Clin Exp Allergy 2001;31: 1544-52.
Strachan DP, Carey IM. Home environment and severe asthma in adolescence: a population based case-control study. BMJ 1995;311: 1053-6.
Strachan DP, Carey IM. Reduced risk of wheezing in children using feather pillows is confirmed. BMJ 1997;314: 518.
Andrae S, Axelson O, Bjorksten B, Fredriksson M, Kjellman NI. Symptoms of bronchial hyperreactivity and asthma in relation to environmental factors. Arch Dis Child 1988;63: 473-8.
Brunekreef B, Dockery DW, Speizer FE, Ware JH, Spengler JD, Ferris BG. Home dampness and respiratory morbidity in children. Am Rev Respir Dis 1989;140: 1363-7.
Williamson IJ, Martin CJ, McGill G, Monie RD, Fennerty AG. Damp housing and asthma: a case-control study. Thorax 1997;52: 229-34.
Shaheen SO, Sterne JA, Thompson RL, Songhurst CE, Margetts BM, Burney PG. Dietary antioxidants and asthma in adults: population-based case-control study. Am J Respir Crit Care Med 2001;164: 1823-8.
Woods RK, Walters EH, Raven JM, Wolfe R, Ireland PD, Thien FC, et al. Food and nutrient intakes and asthma risk in young adults. Am J Clin Nutr 2003;78: 414-21.(Gary W K Wong, professor1)