the total asthma prevalence in children of 14 years and young increased with 64.8% in urban areas of major cities in china from 1990 to 2001 . the increasing prevalence of asthma and related atopic disorders has been documented in many studies using the similar questionnaire from the international study of asthma and allergies in childhood . with the development of economics and fast urbanization in china , a wide difference of environment people live has occurred between urban and rural areas , which may relate to differences in asthma prevalence between urban and rural areas . however , there are only a few studies on the prevalence of childhood asthma in rural areas compared with an increasing number of surveys of childhood asthma in urban areas of china . in china , achieving adequate asthma diagnosis and treatment in pediatric patients has become a key point in control of symptoms . treatment with regular inhaled corticosteroids ( ics ) was associated with improved asthma control and reduced asthma medication use . despite clinical guidelines , such as the global initiative for asthma ( gina ) , beijing was one of the cities involved in the third nationwide survey of childhood asthma in china . children younger than 14 years of age in urban and rural areas were recruited for the survey . the purpose of this study was to compare the prevalence , diagnosis , and treatment of asthma in children between urban and rural areas . these children were born between july 1995 and june 2010 , but baby from the neonatal period was not included in . children enrolled were requested either born in beijing or lived in beijing for more than 6 months . the rural areas in the study were the fangshan district located in the southwest of beijing and the tongzhou district located in the southeast of beijing . the children were randomly selected by cluster random sampling in schools , kindergartens , and communities . based on the data from a previous epidemiological survey and an analysis of children 's asthma in beijing in 2000 , the prevalence of childhood asthma in urban areas was 2.69% . with a level of confidence of 95% , power of 80% , and tolerance error of 0.538% , we estimated that 3,617 children would be a sufficient number in urban areas to estimate population statistics . because the prevalence of childhood asthma in a rural area was not available , we expected that the prevalence of childhood asthma in rural areas was 1.89% , according to a survey of adult asthma . with a level of confidence of 95% , power of 80% , and tolerance error of 0.378% , we estimated that 5281 children would be sufficient in rural areas . according to screening questionnaires which were filled by parents , the children with suspected asthma were selected and given on - the - spot inquiries and examined by two experts to diagnose whether they had asthma . if the diagnosis by the two experts differed , the child was reassessed . the previous diagnosis , medicine treatment , and control of symptoms of asthmatic children were further investigated through face - to - face questionnaire surveys written by the investigators . to reduce recall bias , the same screening questionnaires for the national epidemiological survey of childhood asthma were distributed to parents of children in schools , kindergartens , and communities between october 2010 and march 2011 . the questionnaires were written in chinese and included questions on demographics , eight questions about respiratory diseases and another eight about allergy history . the questions on respiratory problems were : ( 1 ) did the child have any symptoms of wheezing ? ( 2 ) did the child have any symptoms of wheezing in the past 12 months ? ( 3 ) did the child 's wheezing sound like whistling ? ( 4 ) was the child diagnosed with respiratory diseases such as asthma , asthmatic bronchitis , bronchiolitis , or asthmatic pneumonia by a physician ? ( 5 ) has the child had coughing every day in the past 1-month ? ( 6 ) has the child had repeated  respiratory infections  in the past 12 months ? suspected asthma was defined as getting a  yes  on any of questions 14 or answering asthma diagnosis was made following the guidelines in global strategy for asthma management and prevention . typical asthma meant more than one symptom ( wheeze , shortness of breath , cough , chest tightness ) . these symptoms were often worse at night or in the early morning and varied over time and in intensity , and symptoms were controlled by asthma treatment . features of cough variant asthma ( cva ) suggest that chronic cough ( > 4 weeks ) is the principal symptom . in this survey , 101 screening questionnaires were not completed for lack of a phone number . eighteen ( 0.25% ) questionnaires in rural and 83 ( 0.61% ) in urban areas were not completed . all data were entered by epi info version 3.5.1 ( centers for disease control and prevention , usa ) using double entry by two independent persons . data were categorized and analyzed using the statistical package for social sciences software ( spss , version 19.0 , armonk , ny : ibm corp , usa ) . the chi - square test was used to compare prevalence rates of disease and treatment between groups . the mann whitney u was used to compare the control of symptoms between groups for abnormal distribution . these children were born between july 1995 and june 2010 , but baby from the neonatal period was not included in . children enrolled were requested either born in beijing or lived in beijing for more than 6 months . the rural areas in the study were the fangshan district located in the southwest of beijing and the tongzhou district located in the southeast of beijing . the children were randomly selected by cluster random sampling in schools , kindergartens , and communities . based on the data from a previous epidemiological survey and an analysis of children 's asthma in beijing in 2000 , the prevalence of childhood asthma in urban areas was 2.69% . with a level of confidence of 95% , power of 80% , and tolerance error of 0.538% , we estimated that 3,617 children would be a sufficient number in urban areas to estimate population statistics . because the prevalence of childhood asthma in a rural area was not available , we expected that the prevalence of childhood asthma in rural areas was 1.89% , according to a survey of adult asthma . with a level of confidence of 95% , power of 80% , and tolerance error of 0.378% , we estimated that 5281 children would be sufficient in rural areas . according to screening questionnaires which were filled by parents , the children with suspected asthma were selected and given on - the - spot inquiries and examined by two experts to diagnose whether they had asthma . if the diagnosis by the two experts differed , the child was reassessed . the previous diagnosis , medicine treatment , and control of symptoms of asthmatic children were further investigated through face - to - face questionnaire surveys written by the investigators . to reduce recall bias , the same screening questionnaires for the national epidemiological survey of childhood asthma were distributed to parents of children in schools , kindergartens , and communities between october 2010 and march 2011 . the questionnaires were written in chinese and included questions on demographics , eight questions about respiratory diseases and another eight about allergy history . the questions on respiratory problems were : ( 1 ) did the child have any symptoms of wheezing ? ( 2 ) did the child have any symptoms of wheezing in the past 12 months ? ( 3 ) did the child 's wheezing sound like whistling ? ( 4 ) was the child diagnosed with respiratory diseases such as asthma , asthmatic bronchitis , bronchiolitis , or asthmatic pneumonia by a physician ? ( 5 ) has the child had coughing every day in the past 1-month ? ( 6 ) has the child had repeated  respiratory infections  in the past 12 months ? suspected asthma was defined as getting a  yes  on any of questions 14 or answering asthma diagnosis was made following the guidelines in global strategy for asthma management and prevention . typical asthma meant more than one symptom ( wheeze , shortness of breath , cough , chest tightness ) . these symptoms were often worse at night or in the early morning and varied over time and in intensity , and symptoms were controlled by asthma treatment . features of cough variant asthma ( cva ) suggest that chronic cough ( > 4 weeks ) is the principal symptom . investigators distributed 21,805 screening questionnaires to parents of children and acquired 20,823 questionnaires . in this survey , 101 screening questionnaires were not completed for lack of a phone number . eighteen ( 0.25% ) questionnaires in rural and 83 ( 0.61% ) in urban areas were not completed . all data were entered by epi info version 3.5.1 ( centers for disease control and prevention , usa ) using double entry by two independent persons . data were categorized and analyzed using the statistical package for social sciences software ( spss , version 19.0 , armonk , ny : ibm corp , usa ) . the chi - square test was used to compare prevalence rates of disease and treatment between groups . the mann whitney u was used to compare the control of symptoms between groups for abnormal distribution . results are presented as 95% confidence intervals where appropriate . a p < 0.05 was considered significant . questionnaires were completed for 13,513 children in urban areas ( boys , 7190 ) and 7209 children in rural areas ( boys , 3732 ) . the sex distribution of children was not statistically different (  = 3.8 , p = 0.05 ) . the age of children involved in the investigation was 7.7  4.0 years in rural areas and 7.1  4.1 years in urban areas . the total asthma prevalence was 2.83% ( 587/20,722 ) based on screening questionnaires , on - the - spot inquiries , and physical examinations . the asthma prevalence in rural areas was lower than in urban areas ( 1.25% vs. 3.68% , p < 0.001 ) . two - thirds of asthmatic children ( 60/90 , 66.6% ) in rural areas were diagnosed with typical asthma , which was also lower than in children in urban areas ( 451/497 = 90.7% ,  = 39.2 , p < 0.01 ) . cva prevalence was not different between urban and rural areas ( p > 0.05 ) [ table 1 ] . the prevalence of childhood asthma in beijing rural areas and urban areas 95% ci : the rate of 95% confidence intervals ; cva : cough variant asthma . investigators recruited 7338 younger children ( 5 years old ) ( 4927 in urban and 2411 in rural areas ) and 13,384 older children ( > 5 years old ) ( 8586 in urban and 4798 in rural areas ) . the prevalence of asthma was 3.11% ( 416/13,384 ) in older children , which was higher than that in younger children ( 2.33% , 171/7338 ,  = 10.4 , p < 0.01 ) . in urban areas , the asthmatic rate in older children was also higher than that in younger children ( 4.17% vs. 2.83% ,  = 16.1 , p < 0.01 ) . however , in rural areas , age did not affect the prevalence of asthma ( 1.21% vs. 1.33% ,  = 0.2 , p = 0.669 ) . in both the younger and older groups , the prevalence of asthma was lower in rural than in urban areas ( p < 0.05 ) [ table 1 ] . the prevalence of asthma in males was 3.69% ( 4033/10,926 ) , but it was only 1.88% ( 184/9796 ) in females (  = 61.5 , p < 0.01 ) . in urban areas , the prevalence of asthma in males was double that of females ( 4.80% vs. 2.40% ,  = 54.5 , p < 0.01 ) . just as in urban areas , the prevalence of asthma in rural areas was also higher in males than in females ( 1.45% vs. 0.92% , 2 = 5.80 , p = 0.01 ) . whether male or female , the prevalence of asthma in rural areas was lower than in urban areas ( p < 0.05 ) [ table 1 ] . we investigated previous diagnoses and use of medication and found that 26.1% ( 153/587 ) of asthmatic children had never been diagnosed with asthma . the percentage of previous asthmatic diagnoses in rural areas was much lower than in urban areas ( 48.9% vs. 78.5% ,  = 34.6 , p < 0.001 ) . in asthmatic children from rural areas , 11.1% were incorrectly diagnosed with pneumonia , 28.9% with bronchitis , and 11.1% with other conditions . for asthmatic children in urban areas , 3.2% were misdiagnosed with pneumonia , 12.9% with bronchitis , and 5.4% with others [ figure 1 ] . table 2 shows asthma symptoms , such as total number of wheezing , the times of wheezing in the past 1-year , the times of wheezing in the most severe year , and total months with wheezing in the most severe year . the median ( interquartile range ) was used to describe the control levels of asthma . except for total months with wheezing in the most severe year , symptoms were not statistically different between the children with asthma in city and children with asthma in the countryside ( p > 0.05 ) . frequency of asthma episodes in children from beijing ( median ( p25p75 ) ) among the rural asthmatic children , only 35.6% ( 32/90 ) reported that they used ics as compared with 56.6% ( 281/497 ) of asthmatic children in urban areas (  = 13.5 , p < 0.01 ) . just as with ics , the usage of bronchodilators was lower in rural areas than in urban areas ( 41/90 = 45.6% vs. 330/497 = 66.4% ,  = 14.2 , p < 0.01 ) . although the usage of theophylline was higher in rural areas , the difference was not statistically significant ( p > 0.05 ) . the usage of medicine , such as systemic corticosteroids , leukotriene receptor antagonists , antihistamines , specific immunotherapy , antibiotics , and chinese medicine , were not significantly different ( p > 0.05 ) [ figure 2 ] . ics : inhaled corticosteroids ; ocs : oral corticosteroids ; ltras : leukotriene receptor antagonists . * the total asthma prevalence was 2.83% ( 587/20,722 ) based on screening questionnaires , on - the - spot inquiries , and physical examinations . the asthma prevalence in rural areas was lower than in urban areas ( 1.25% vs. 3.68% , p < 0.001 ) . two - thirds of asthmatic children ( 60/90 , 66.6% ) in rural areas were diagnosed with typical asthma , which was also lower than in children in urban areas ( 451/497 = 90.7% ,  = 39.2 , p < 0.01 ) . cva prevalence was not different between urban and rural areas ( p > 0.05 ) [ table 1 ] . the prevalence of childhood asthma in beijing rural areas and urban areas 95% ci : the rate of 95% confidence intervals ; cva : cough variant asthma . investigators recruited 7338 younger children ( 5 years old ) ( 4927 in urban and 2411 in rural areas ) and 13,384 older children ( > 5 years old ) ( 8586 in urban and 4798 in rural areas ) . the prevalence of asthma was 3.11% ( 416/13,384 ) in older children , which was higher than that in younger children ( 2.33% , 171/7338 ,  = 10.4 , p the asthmatic rate in older children was also higher than that in younger children ( 4.17% vs. 2.83% ,  = 16.1 , p < 0.01 ) . however , in rural areas , age did not affect the prevalence of asthma ( 1.21% vs. 1.33% ,  = 0.2 , p = 0.669 ) . in both the younger and older groups , the prevalence of asthma was lower in rural than in urban areas ( p < 0.05 ) [ table 1 ] . the prevalence of asthma in males was 3.69% ( 4033/10,926 ) , but it was only 1.88% ( 184/9796 ) in females (  = 61.5 , p < 0.01 ) . in urban areas , the prevalence of asthma in males was double that of females ( 4.80% vs. 2.40% ,  = 54.5 , p < 0.01 ) . just as in urban areas , the prevalence of asthma in rural areas was also higher in males than in females ( 1.45% vs. 0.92% , 2 = 5.80 , p = 0.01 ) . whether male or female , the prevalence of asthma in rural areas was lower than in urban areas ( p < 0.05 ) [ table 1 ] we investigated previous diagnoses and use of medication and found that 26.1% ( 153/587 ) of asthmatic children had never been diagnosed with asthma . the percentage of previous asthmatic diagnoses in rural areas was much lower than in urban areas ( 48.9% vs. 78.5% ,  = 34.6 , p < 0.001 ) . in asthmatic children from rural areas , 11.1% were incorrectly diagnosed with pneumonia , 28.9% with bronchitis , and 11.1% with other conditions . for asthmatic children in urban areas , 3.2% were misdiagnosed with pneumonia , 12.9% with bronchitis , and 5.4% with others [ figure 1 ] . table 2 shows asthma symptoms , such as total number of wheezing , the times of wheezing in the past 1-year , the times of wheezing in the most severe year , and total months with wheezing in the most severe year . the median ( interquartile range ) was used to describe the control levels of asthma . except for total months with wheezing in the most severe year , symptoms were not statistically different between the children with asthma in city and children with asthma in the countryside ( p > 0.05 ) . among the rural asthmatic children , only 35.6% ( 32/90 ) reported that they used ics as compared with 56.6% ( 281/497 ) of asthmatic children in urban areas (  = 13.5 , p < 0.01 ) . just as with ics , the usage of bronchodilators was lower in rural areas than in urban areas ( 41/90 = 45.6% vs. 330/497 = 66.4% ,  = 14.2 , p < 0.01 ) . although the usage of theophylline was higher in rural areas , the difference was not statistically significant ( p > 0.05 ) . the usage of medicine , such as systemic corticosteroids , leukotriene receptor antagonists , antihistamines , specific immunotherapy , antibiotics , and chinese medicine , were not significantly different ( p > 0.05 ) [ figure 2 ] . ics : inhaled corticosteroids ; ocs : oral corticosteroids ; ltras : leukotriene receptor antagonists . * this study is the first comparing the prevalence of asthma , diagnosis , and medical treatment between urban and rural areas using the screening questionnaires and on - the - spot inquiries in china . results of this study demonstrated that there was a lower prevalence of asthma in rural children ( 1.25% ) compared with urban children ( 3.68% ) . in both rural and urban areas the result above was comparable to what ma reported that prevalence of asthma in rural chinese children was significantly lower than in urban children , and what garcia - marcos et al . the rural asthmatic rate in our study was lower than the results from south india study , which was conducted in school children . the large age range in our study may account for the difference of asthma prevalence between the two studies . in our study , the lowest age of child found with asthma was 2 years and 9 months in rural areas , and the lowest age of children with asthma was 2 months and 28 days in urban areas . compared with the only questionnaire - based study , it is uncertain how the result of asthma prevalence was affected by screening questionnaires , on - the - spot inquiries , and examination . last of all , difference of ethnic and regional factor might also exert influence on asthma prevalence . the reason for a lower prevalence of asthma in rural areas is unclear . in one study , conversely , particulate air pollution , which adversely affects lung function in asthmatics , was higher in urban locations compared with rural locations . the low prevalence of asthma in children in rural areas of beijing might be attributed to these two factors . another new finding may help to characterize children with asthma in rural and urban areas in our study . there was an interesting phenomenon that compared with younger children , older children were more likely to have asthma in urban areas ; however , this phenomenon was not found in rural areas . although this has not been reported in other studies of asthma , research on allergic airway diseases such as allergic rhinitis has reported a similar phenomenon . children who live in urban areas had more exposure to air pollution than children from rural areas and had more aeroallergen sensitization . this may explain why the prevalence of asthma in older children was high in urban areas than in rural areas . in the global strategy for asthma management and prevention , treatment with a regular daily low dose of ics is highly effective in reducing asthma symptoms and reducing the risk of asthma exacerbation . however , we found that only 36% of asthmatic children in rural areas used ics , which was lower than in urban areas . the factors accounting for low ics use may be as follows : first , the rate of asthmatic diagnoses previously in rural areas was extremely low , which obviously resulted in low usage of ics ; the second reason for the low usage of ics might be that patients with asthma diagnosed were not treated according to guidelines ; and in the third , the availability of ics was influence factor as well . even in children with asthma diagnosed previously , only 54.6% of these children used ics in our study . despite many guidelines and drugs for control of asthma were available at present , the dissemination and implementation of the guideline in rural are still challenges in china . the use of practical tools that assesses the gina criteria for asthma control , such as the asthma control test ( act ) and childhood act , may assist with quick ( within 4 weeks ) identification of pediatric patients with suboptimal asthma control . in our survey , we analyzed asthma symptoms such as total number of wheezing , the total incidents of wheezing in the past 1-year , and total incidents of wheezing in the most severe year . these data were not different between urban asthmatic children and rural asthmatic children . a lack of regular use of ics results in low control of symptoms in both urban and rural areas . even though the regular use of ics was not investigated in our study , zhang et al . reported that only one - third of asthmatic children adhered to the use of ics in beijing urban areas . daily ics resulted in a significant increase in asthma - free days , improved asthma control , and reduced use of additional asthma medication . irregular ics may lead to high frequent use of bronchodilators although more ics was used in asthmatic children in urban areas . furthermore , poor control of concomitant allergic rhinitis may have also contributed to the poor control of asthma ; this relationship has been well - documented in the literature . lung function test was not included in our survey due to the limitation of performance ability from different ages of children , even though this test is an important criterion for asthma diagnosis and control . and also for studies in schools , kindergartens , and communities , the equipment for lung function tests was not available . in our study , there was probably recall bias about previous diagnosis and treatment in some old children with long time of history with or without disease , but outpatient service books were included in our study to reduce the bias , even though it did happen in certain case that the parents forgot to take it to the field . last of all , lead time bias is inevitable , and it is estimated that the prevalence of asthma might be higher than its true value . however , findings from this study show that the prevalence and treatment of asthma in children in rural areas were lower compared with children with asthma in urban areas . the diagnosis and treatment of asthma in children this study was supported by a grant from capital medical development research fund ( no . this study was supported by a grant from capital medical development research fund ( no .
background : the prevalence of childhood asthma has been increasing in china . 
 this study aimed to compare the prevalence , diagnosis , and treatment of asthmatic children from urban and rural areas in beijing , china.methods:schools , communities , and kindergartens were randomly selected by cluster random sampling from urban and rural areas in beijing . 
 parents were surveyed by the same screening questionnaires . 
 on - the - spot inquiries , physical examinations , medical records , and previous test results were used to diagnose asthmatic children . 
 information on previous diagnoses , treatments , and control of symptoms was obtained.results:from 7209 children in rural areas and 13,513 children in urban areas who completed screening questionnaires , 587 children were diagnosed as asthma . 
 the prevalence of asthma in rural areas was lower than in urban areas ( 1.25% vs. 3.68% , 2 = 100.80 , p < 0.001 ) . 
 the diagnosis of asthma in rural areas was lower than in urban areas ( 48.9% vs. 73.9% , 2 = 34.6 , p < 0.001 ) . compared with urban asthmatic children ( 56.5% ) , 
 only 35.6% of rural asthmatic children received inhaled corticosteroids ( p < 0.05 ) . 
 the use of bronchodilators was also lower in rural areas than in urban areas ( 56.5% vs. 66.4% , 2 = 14.2 , 
 p < 0.01).conclusion : the prevalence of asthma in children was lower in rural areas compared with children in the urban area of beijing . 
 a considerable number of children were not diagnosed and inadequately treated in rural areas .