Epidemiological survey and analysis of asthma in children aged 0-14 years old in urban and rural areas of Chengdu region

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1 Originl Article Epidemiologicl survey nd nlysis of sthm in children ged 0-14 yers old in urbn nd rurl res of Chengdu region Min Li 1, Qiong Zhng 2, Wei-Jun Shi 2, Ln Li 1, Yn Li 2, Ying Png 1, Bin Yo 1, Hong Jing 1 1 Deprtment of Peditrics, Sichun Acdemy of Medicl Sciences nd Sichun Province People s Hospitl, Chengdu , Chin; 2 Deprtment of Peditrics, First people s Hospitl of Jintng County, Chengdu , Chin Correspondence to: Min Li. Deprtment of Peditrics, Sichun Acdemy of Medicl Sciences nd Sichun Province People s Hospitl, Chin. Emil: Lmscsy@liyun.com. Objectives: To investigte the prevlence nd incidence of sthm mong children ged 0-14 yers, with different living environments, economic levels, nd snitry conditions, in the urbn nd rurl res of Chengdu, Chin, nd their influentil fctors. Methods: Children ged 0-14 yers who were selected from urbn, suburbn, nd rurl res of Chengdu were included in the study. The subjects were selected from ll children ged 0-14 yers in schools, kindergrtens, nd communities by rndom, cluster nd non-proportionl smpling. Prents were surveyed by questionnire to find out suspected cses, which were then confirmed by inquiry nd physicl exmintion in the deprtments of respirtory medicine. All the obtined dt were nlyzed using SPSS sttisticl softwre. Results: A totl of 12,082 children from the urbn res, 5,677 from suburbn res, nd 5,590 from the rurl res were included in the study. Of ll the subjects, 551 (4.56%) hd confirmed sthm, 150 (2.64%) hd cough vrint sthm (CVA), nd 142 (2.54%) hd suspected sthm. The prevlence rte of sthm ws significntly higher in the urbn res thn in the suburbn nd rurl res. The correct rte of dignosis of sthm nd CVA ws highest in the urbn res, followed by the suburbn nd rurl res. Use of ntibiotics nd systemic corticosteroids ws most common in the rurl res, followed by the suburbn nd urbn res, but this pttern ws reversed for use of inhled corticosteroids nd leukotriene modifier. All the results in the three res demonstrted tht sex, ge, ge t which the first ttck occurred, respirtory trct infection, inhltion/intke of llergens, nd genetic fctors were significntly ssocited with sthmtic ttck. Conclusions: Popultion density, living environment, medicl nd helth resources nd economic level re ssocited with the prevlence nd tretment of sthm. Keywords: Epidemiology; sthm; children Submitted Oct 18, Accepted for publiction Oct 24, doi: /j.issn View this rticle t: Bronchil sthm (or sthm) is one of the most common chronic respirtory diseses in children. Globlly, the pst decdes hve witnessed the rpid development of socioeconomy, sciences, nd technology; unfortuntely, the prevlence of sthm hs lso grdully incresed. Up to now two lrge-scle epidemiologicl surveys on childhood sthm hve been conducted in Chin (1,2); however, both of them were focused on children living in big cities, nd few dt concerning the prevlence of sthm mong children living in the sme re but with different living conditions, different economic levels, nd different snittion environments hve been reported. Therefore, in our current study, we conducted n epidemiologicl survey on sthm using cluster smpling method mong 0-14-yer-old children in Chengdu, cpitl of Sichun Province, from September to December 2010.

2 Trnsltionl Peditrics, Vol 2, No 4 October Tble 1 Asthm cses in three res [n (%)] Groups n Asthm Cough-vrint sthm Suspected sthm Urbn re 12, (4.01) 66 (0.55) 97 (0.81) Suburbn re 5, (2.41) 13 (0.23) 32 (0.56) Rurl re 5, (2.38) 9 (0.16) 21 (0.31) Subjects nd methods Subjects By dpting the protocol developed by the Tsk Force on the Third Ntionl Epidemiologicl Survey on sthm mong 0-14-yer-old children, we selected children ged 0-14 yers who were born during the period from July 1, 1996 to June 61, 2010) from urbn (Qingyng District of Chengdu), suburbn (Chenggun Town of Jintng County), nd rurl (Zhuho Town of Jintng County) res of Chengdu s subjects in our projects. According to the smple size clcultion formul (N = Uα 2 π (1-π)/δ 2 ) nd the totl child popultions in these three res, the smple sizes were 12,000, 6,000, nd 6,000 in the urbn, suburbn, nd rurl res. Bsed on the totl child popultions nd the percentges of children in different ge groups, the smple size for ech ge group ws clculted. Finlly, the subjects were selected from ll children ged 0-14 yers in schools, kindergrtens, nd communities by rndom, cluster, nd non-proportionl smpling. The dignosis of sthm in these children ws bsed on the Guidelines for the Dignosis nd Tretment of Asthm in Children (2008 edition) (3). The dignoses included confirmed sthm, cough vrint sthm (CVA), nd suspected sthm. Survey methods The protocol, survey steps, nd questionnires used in the Third Ntionl Epidemiologicl Survey on sthm mong 0-14-yer-old children were dpted in our study. Before the initition of the survey, ll the investigtors received dequte trining in the 2010 Workshop on Ntionl Epidemiologicl Survey on Asthm in Children. The investigtors registered ll the smpled popultions firstly, nd then distributed the screening forms to the prents; fter these forms were collected, suspected children with wheezing, cough, repeted respirtory trct infection, or history of bronchitis were identified. Respirtory specilist physicins who hd received uniform trining crried out comprehensive inquiry nd physicl exmintions using the stndrd questionnires, nd then mde the finl dignosis nd completed the sthm questionnires. During the survey, specil supervisors re ssigned for orgniztion, supervision, nd qulity control. Sttisticl nlysis Dtbse ws estblished using the Epi Info softwre for dt entry nd logicl checks. Sttisticl nlysis of the dt ws performed using SPSS softwre. Mesurement dt re described using percentges, nd chi squre test is pplied for inter-group comprisons. P<0.05 ws considered significntly different. Results Generl conditions Prevlence It ws expected tht 12,270, 5,886, nd 5,821 children should hve been surveyed in the urbn, suburbn, nd rurl res, nd ctully 12,082 (98.47%), 5,677 (96.45%), nd 5,590 (96.03%) children were surveyed. The mjority of the surveyed popultions were Hn children, followed by other ethnic groups including Tibet, Hui, Mnchu, nd Koren. A totl of 993 children with relted diseses were screened in these three res (Tble 1). Except children with suspected sthm, the cumultive incidence rtes in the urbn, suburbn, nd rurl res were 4.56%, 2.64%, nd 2.54%, respectively (χ 2 =65.025, P<0.01); notbly, the cumultive incidence rte in the urbn re ws significntly higher thn those in the suburbn nd rurl res (P<0.01). Except cses tht hd not except excerbtions for more thn two yers, the prevlence of sthm in these three res ws 3.58%, 1.81%, nd 2.08%, respectively. Asthm in mle nd femle children The prevlence rtes of sthm were significntly higher in mles thn in femles in ll three res (ll P<0.01) (Tble 2).

3 162 Li et l. Asthm in children in urbn nd rurl res Asthm in children of different ge groups The prevlence rtes of sthm were reltively high in the 3-10-yer-old ge group in ll three res, nd then grdully declined s the children become older (Tble 3). Previous dignoses During our current survey, 68.4% (377/551), 43.3% (65/150), nd 28.2% (40/142) of the peditric ptients hd previously been dignosed s with sthm or CVA (χ 2 =88.99, P<0.01). The correct rte of dignosis of sthm nd CVA ws highest in the urbn res, followed by the suburbn nd rurl res. Tble 2 Prevlence rte of sthm in mles nd femles in three res [n (%)] Groups Mle Femle n Prevlence n Prevlence Urbn re 6, (5.77) 5, (3.32) Suburbn re 2, (2.85) 2, (2.43) Rurl re 2, (3.09) 2, (1.97) χ 2 vlue P vlue <0.001 Asthm ttcks Triggers for n cute sthm ttck The min trigger for n cute sthm ttck mong these children ws respirtory trct infections (91.3%), followed by climte chnge (43.8%). Only smll proportion of the ttcks were cused by pollen llergy (6.6%) (Tble 4). Age of the first sthm ttck Infnts nd young children under four yers old hd the highest rte of the first sthm ttck in ll three res (76.6%, 81.3%, nd 77.5%), which declined with ge (Tble 5). Timing nd predilection sesons The timing of the cute ttcks showed no specific rule mong most sthm children in ll these three res. Asthm ttck ws more common in utumn, winter, nd during sesonl chnges. Children living in the urbn re were significntly more likely to experience sthm ttcks in utumn nd winter thn those in suburbn nd rurl res (P<0.05) (Tbles 6,7). Disese courses Till the end of our current survey, the sthm ttcks/ excerbtions were found in 33 (6.0%), 14 (9.3%), nd 17 (12.0%) peditric ptients in the urbn, suburbn, nd Tble 3 Asthm in children of different ge groups [n (%)] Age (yers) Urbn re Suburbn re Rurl re n Prevlence n Prevlence n Prevlence (0) (0.68) 56 0 (0) (1.69) (1.18) 87 2 (2.30) (3.60) (1.17) 76 1 (1.32) (7.18) (4.49) (5.34) (8.13) (5.09) (4.41) (8.23) (6.35) (1.55) (5.18) (1.72) (3.13) 7-1, (5.45) (2.19) (2.51) 8-1, (4.60) (3.08) (2.88) 9-1, (4.32) (3.02) (3.84) 10-1, (3.79) (1.80) (2.18) 11-1, (2.83) (1.93) (1.77) 12-1, (3.11) (1.33) (1.87) (4.41) (1.49) (1.35) (1.72) (1.28) 83 1 (1.20)

4 Trnsltionl Peditrics, Vol 2, No 4 October Tble 4 Triggers of sthm ttcks in three res [n (%)] Group tstes n Respirtory trct infection Climte chnge Foods Irrittive Sports Pollen Urbn re (90.4) 272 (49.4) 76 (13.8) 186 (33.8) 130 (23.6) 44 (8.0) Suburbn re (87.3) 70 (46.7) 16 (10.7) 59 (39.3) 29 (19.3) 10 (6.7) Rurl re (99.3) 72 (50.7) 18 (12.7) 50 (35.2) 32 (22.5) 2 (1.4) Totl (91.3) 414 (43.8) 110 (13.0) 295 (35.0) 191 (22.7) 56 (6.6) Tble 5 Age of the first sthm ttck of children in three res [n (%)] Group n Below yer-old 7-14-yer-old Urbn re (76.6) 99 (18.0) 30 (5.5) Suburbn re (81.3) 19 (12.7) 9 (6.0) Rurl re (77.5) 21 (14.8) 11 (7.8) Tble 6 Timing of sthm ttcks in three res [n (%)] Group n Morning Afternoon Before sleep Midnight Irregulr Urbn re (12.3) 9 (1.6) 102 (18.5) 132 (24.0) 240 (43.6) Suburbn re (22.7) 2 (1.3) 17 (11.3) 28 (18.7) 69 (46.0) Rurl re (14.8) 4 (2.8) 0 (0) 23 (16.2) 94 (66.2) χ 2 vlue P vlue <0.01 >0.05 <0.05 >0.05 <0.01 Tble 7 Predilection sesons of sthm ttcks in three res [n (%)] Group n Autumn nd winter Spring nd summer Trnsitions of sesons Throughout the yer Irregulr Urbn re (32.1) 55 (10.0) 161 (29.2) 10 (1.8) 148 (26.9) Suburbn re (20. 7) 23 (15.3) 50 (33.3) 2 (1.3) 44 (29.3) Rurl re (12.7) 7 (4.9) 84 (59.2) 0 (0) 33 (23.2) χ 2 vlue P vlue <0.01 <0.05 <0.01 >0.05 >0.05, P<0.05, compred with the suburbn nd rurl res. rurl res, respectively, wheres sthm relief ws chieved in 202 (36.7%), 41 (27.3%), nd 37 (26.1%) ptients. Obviously, the percentge of sthm ttck/excerbtion grdully incresed from the urbn re to the rurl re (P<0.05), while the percentge of sthm relief grdully declined (P<0.05). About 14-22% of the peditric ptients hd not experienced sthm ttcks for more thn two yers (Tble 8). round 90% of the ptients, nd the ntibiotic usge rte ws significntly higher in the rurl re thn in the urbn nd suburbn res. The use of inhled corticosteroids grdully decresed from the urbn re to the suburbn re, nd then to the rurl re; the use of leukotriene modifiers showed similr trend; nd, the usge rtes of systemic hormones were prticulrly high in the rurl re (Tble 9). Tretment In ll these three res, over 80% of the peditric sthmtic ptients hd used bronchodiltors. Antibiotics were used in Helth cre costs for sthm The overll helth cre costs since the disese onset ws below RMB 10,000 in more thn hlf of the peditric

5 164 Li et l. Asthm in children in urbn nd rurl res Tble 8 Trends of sthm ttcks in three res [n (%)] Group n Excerbtion Unchnged Relief No ttck within No ttck fter Attck fter one one yer two yers or more yers Urbn re (6.0) 90 (16.3) b 202 (36.7) 83 (15.1) 118 (21.4) 25 (4.5) Suburbn re (9.3) 30 (20.0) 41 (27.3) 21 (14.0) 33 (22.0) 11 (7.3) Rurl re (12.0) 40 (28.2) 37 (26.1) 14 (9.9) 20 (14.1) 14 (9.9) χ 2 vlue P vlue <0.05 <0.01 <0.05 >0.05 >0.05 >0.05, P<0.05 compred with the suburbn re nd rurl re; b, P<0.05 compred with the rurl re. Tble 9 Tretment of sthm in three res [n (%)] Group n Bronchodiltors Systemic Inhled Antileukotrienes Immune Desensitiztion Trditionl hormones steroids Antibiotics modultors therpy Chinese drugs Urbn res (91.3) 194 (35.2) 383 (69.5) 176 (31.9) 350 (63.5) 76 (13.8) 21 (3.8) 490 (88.9) b 335 (60.8) Suburbn 150 re 134 (89.3) 48 (32.0) 57 (38.0) 19 (12.7) 94 (62.7) 3 (2.0) 3 (2.0) 134 (89.3) b 109 (72.7) Rurl re (80.3) 85 (59.9) 32 (22.5) 8 (5.6) 115 (81.0) 2 (1.4) 1 (0.7) 139 (97.9) 128 (90.1) χ 2 vlue P vlue <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 >0.05 <0.01 <0.01, P<0.05 compred with the suburbn re nd rurl re; b, P<0.05 compred with the rurl re. Tble 10 Personl history of llergy in three res [n (%)] Group n History of eczem History of llergic rhinitis History of urticri History of drug llergy Urbn re (45.9) 286 (51.9) b 134 (24.3) 97 (17.6) Suburbn re (25.3) 74 (49.3) 22 (14.7) 16 (10.7) Rurl re (14.8) 52 (36.6) 11 (7.7) 14 (9.9) χ 2 vlue P vlue <0.05 <0.05 <0.05 <0.05, P<0.05, compred with the suburbn nd rurl res; b, P<0.05, compred with the rurl re. sthm ptients; however, due to the differences in fmily income, eductionl level, nd prents concerns bout their children, the helth cre costs were below RMB 2,000 in 71.8% of rurl peditric ptients nd exceeded RMB 30,000 in 5.8% of urbn peditric ptients. Asthm-relted fctors Personl history of llergy The prevlence rtes of vrious llergic diseses were significntly highest mong children living in the urbn re, followed by the suburbn nd rurl res (P<0.05) (Tble 10). Fmily history of llergy The proportions of children with fmily history of sthm in their first- or second-degree reltives were 27.2%, 28.0%, nd 42.3% in the urbn, suburbn, nd rurl res, nd the fmily history of other llergies were reported in 37.6%, 16.0%, nd 38.0% of these children (Tble 11). Discussion When choosing the reserch subjects, the inclusion criteri were different from those dopted by two lrgescle surveys on childhood sthm in Chin (1-2,4) nd n epidemiologicl survey conducted in severl mjor

6 Trnsltionl Peditrics, Vol 2, No 4 October Tble 11 Fmily history of llergy in three res [n (%)] Group n History of sthm in the first nd History of other llergies in the first nd second-grde reltives second-grde reltives Urbn re (27.2) 207 (37.6) Suburbn re (28.0) 24 (16.0) Rurl re (42.3) 54 (38.0) χ 2 vlue P vlue <0.01 <0.01 cities in recent yers (5). In ddition to the 0-14-yer-old children in the downtown of Chengdu, children who were living in the suburbn nd rurl res tht hve the sme geologicl loction, seson nd climte chnge but with different popultion density, economic income, helth cre resources, nd life hbits were lso enrolled in this study. The suburbn re (Chenggun Town, Jintng County) ws roughly 100 kilometers wy from Chengdu, wheres the urbn re is hilly town. The results showed tht the cumultive incidence rte of sthm ws significntly higher in the urbn re (4.56%) thn in the suburbn (2.64%) nd rurl res (2.54%). This my be explined by the following fctors: (I) long with the rpid industriliztion nd the increse of socioeconomic levels, the urbn re hs become more populous, nd the number of fmilies hving crs, ir conditioners, nd crpets hs rpidly incresed; s result, the environmentl pollution is more severe in the urbn re thn in suburbn nd rurl res. More children who re prone to llergy re more likely to be ffected by the environmentl triggers (6). Furthermore, children who re living in the urbn re re more likely to exposed to llergenic foods such s eggs nd sefoods when they re t young ge; (II) the Jintng County, locted in the outskirt of Chengdu, is hilly re tht re surrounded by hills nd wters. Compred with the downtown of Chengdu, it is less populous; nd, without environmentl pollution from lrge plnts, it hs much fresher ir; (III) ccording to the Hygiene Hypothesis, children living in the urbn res re less possible to be exposed to the pthogenic microorgnisms due to their good hygiene nd snitry conditions, nd therefore they re less likely to suffer from communicble diseses nd other infectious diseses; s result, however, the Th1 response towrds these microorgnisms is wekened, together with reltively enhnced Th2 response. Thus, children in the urbn res re more susceptible to llergic diseses. As shown in our current study, the peditric sthm children with history of eczem, llergic rhinitis, nd/or other llergic diseses were most common in the urbn re, followed by the suburbn nd rurl res, which is consistent with the literture (7,8). In ddition, significntly higher proportion of mle ptients were found in ll these three res, which is lso consistent with the literture (9,10). The possible explntions include the differences in hormone secretion nd genetic susceptibility; the lower infection threshold in femle crriers of pthogenic genes my lso ply role. Our study lso showed tht the correct rte of dignosis of sthm ws highest in the urbn res, followed by the suburbn nd rurl res. In Chin, the dvoction, trining, nd implementtion of the Globl Inititive for Asthm (GINA) hs gretly improved the erly dignosis of sthm; however, due to the diversities in helth cre resources, professionl levels, socioeconomic development, fmily income, nd prents wreness nd knowledge, the sthm dignosis wrrnts further improvements in different res. The occurrence of sthm is closely linked to environmentl fctors, nd childhood sthm is often ge- nd seson-specific. In our current study, children whose first sthm ttck occurred below 4-yer-old ccounted for over 75% in ll the three res. The most common trigger ws respirtory trct infection, followed by climte chnge nd irrittive tste. The predilection sesons were utumn nd winter s well s the trnsitions of sesons. This my be explined by the fct tht the orgns nd systems re not well developed nd the immune system is not sufficiently robust in infnts nd young children. Our survey lso found tht the proportion of the peditric ptients who hd not experienced sthm ttck for one or two yers ws significntly lower in the rurl re thn in the suburbn nd urbn res; menwhile, from the urbn re to the suburbn nd rurl res, the percentge of sthm excerbtion grdully incresed, wheres tht of sthm relief declined. Although nerly 90% of the peditric ptients in ll these three res hd used ntibiotics, the usge rte of ntibiotics ws significntly higher in the rurl re thn in the suburbn nd urbn res; menwhile, the

7 166 Li et l. Asthm in children in urbn nd rurl res use of inhled hormones inhled steroids nd leukotriene modifiers showed declining trend from the urbn re to the suburbn nd rurl res. Notbly, in recent yers efforts hve been mde by vrious professionl nd cdemic groups to dvocte the GINA protocol mong peditricins, which hs gretly improved the understnding nd mngement of sthm in the mjority of hospitls in the urbn re. However, due to the unequl distribution of medicl resources, the outdted fcilities, poorly trined medicl stff, nd limited helth cre investments in the rurl re hs restricted the medicl stff s ccess to new knowledge nd new techniques. On the other hnd, the residents in the rurl res often hve low income nd lck sufficient wreness nd knowledge bout their children s disese. Mny children in the rurl re only receive ntibiotics or symptomtic tretment during the sthm ttcks, nd will not use ny drug once the symptoms re controlled. As result, significnt proportion of sthmtic children living in the rurl res re not properly mnged. In summry, our current study provided solid evidences for the helth uthorities nd my guide future-decision mking on disese control, prioritized investments in helth cre in rurl re, nd pproprite prevention nd control of childhood sthm. Acknowledgements We re grteful for the trining fund provided by the Bureu of Chronic Diseses, Ministry of Helth s well s the schemtic, technicl, nd finncil supports from the Prevention, Tretment nd Eduction Center for Asthm, Cpitl Institute of Peditrics nd the Institute of Environment nd Helth Relted Product Sfety, Chinese Center for Disese Control nd Prevention. Also, we grtefully cknowledges the prticiption of Dehou Xue, Lin Chen, Deyun Li, nd Hnmin Liu from West Chin Second Hospitl of Sichun University, Xiofn Liu nd others from Chengdu University of trditionl Chinese Medicine, nd Cilin Wng nd others from Chengdu Women s nd Children s Centrl Hospitl in dt collection. Specil thnks re lso due to Qing Wng from Chin CDC for his inputs to dt review nd entry nd Wei Tin from Institute of Medicl Informtion, Sichun Provincil People s Hospitl for his id in dt nlysis. Footnote Conflicts of Interest: The uthors hve no conflicts of interest to declre. References 1. Chen YZ, Ntionl Coopertion Group On Childhood Asthm. A ntionwide survey in Chin on prevlence of sthm in urbn children. Zhonghu Er Ke Z Zhi 2003;41: Ntionl Coopertion Group on Peditric Asthm. Survey on sthm prevlence mong 900, yer-old children in Chin. Chin J Tuberc Respir Dis 1993;16: Subspecilty Group of Respirtory Diseses Society of Peditrics; Chinese Medicl Assocition; Chinese Journl of Peditrics Editoril Bord. Guideline for the dignosis nd optiml mngement of sthm in children. Zhonghu Er Ke Z Zhi 2008;46: Li M, Wng CL, Liu XF, et l. Epidemiologicl Survey on Childhood Asthm in Chengdu. Journl of Preventive Medicine Informtion 2002;18: Bo J, Zho J, Shen KL, et l. Prevlence of Childhood Asthm in Beijing, Chongqing, nd Gungzhou. Chinese Journl of Allergy & Clinicl Immunology 2010;4: McConnell R, Berhne K, Yo L, et l. Trffic, susceptibility, nd childhood sthm. Environ Helth Perspect 2006;114: Riedler J, Brun-Fhrländer C, Eder W, et l. Exposure to frming in erly life nd development of sthm nd llergy: cross-sectionl survey. Lncet 2001;358: Seiskri T, Kondrshov A, Viskri H, et l. Allergic sensitiztion nd microbil lod-- comprison between Finlnd nd Russin Kreli. Clin Exp Immunol 2007;148: Hung S, Wng JH, Hung SK, et l. Survey on the correltion fctors of the pthogenesis of sthm in children in Gungzhou community. The Journl of Prcticl Medicine 2010;26: Li L, Liu JM, Chen Q, et l. Epidemiologicl survey on sthm mong 0-14-yer-old children in the downtown of Nnchng. Jingxi Medicl Journl 2011;46: Cite this rticle s: Li M, Zhng Q, Shi WJ, Li L, Li Y, Png Y, Yo B, Jing H. Epidemiologicl survey nd nlysis of sthm in children ged 0-14 yers old in urbn nd rurl res of Chengdu region.. doi: /j.issn