Br.
THE PREVALENCE OF ASTHMA WHEEZING IN CHILDREN J. The
MORRISON
Asthma
The prevalence of asthma and wheezing in the previous studies in 1968-9 and 1956-7. period, although the rate of increase had Children of the same racial group were diseases, if born in England than if born in life profoundly influence the prevalence of
Clinic,
J. Dis.
Chest
(1976)
70, 73
AND
SMITH Birmingham
children in Birmingham in 1974-5 was compared with The frequency of asthma increased over the 20-year slowed. Asthma was commoner in boys than in girls. more prone to asthma, and probably to other atopic poor tropical countries. Environmental factors in early asthma in childhood.
INTRODUCTION
The prevalence of asthma in children in Birmingham has been studied on three separate occasions, in 1956-7 (Smith 1961), in 1968-9 (Smith et al. 1971) and in 1974-5. The results in 1968-9 suggested that asthma had increased in children in England and that factors in early life influenced the prevalence, in that children born in poor tropical countries were less likely to have asthma than children of the same race born in England. This may be true not only for asthma but also for other atopic diseases. In Birmingham eczema in Negro children who have asthma is just as common as it is in European children with asthma (Smith 1973) and hay fever is virtually unknown in persons born in tropical countries until they have lived in England for several years, although it probably occurs just as frequently in Negro and Asian children born in England as in European children. The present study was undertaken to see if asthma is still increasing in frequency and to assess differences in incidence between European and immigrant children. Methods The information was collected by school health visitors from parents at the routine school medical examinations. They were asked to enquire about already diagnosed asthma first and then about recurrent attacks of wheezing which had not been called asthma. The definitions used for asthma and wheezing and the methods and staff used in the collection of the information have been similar in the three studies. In 1956-7 there were hardly any children who had themselves been born abroad or whose parents had been born abroad, but by 1968-9 large numbers of immigrant children were included. The schools where the examinations were done were widely scattered over the city so that it is likely that they represent a reasonable cross-section of the population of Birmingham in relation to social class. Previous experience in 1956-7 had shown that recurrent wheezing attacks in children of school age are unlikely to be due to causes other than asthma, although those not called asthma by the family doctor are likely to be less severe and persistent and to carry a better prognosis than those definitely so diagnosed (Smith 1961; Smith et al. 1971). Interpreters were available for communication with Asian parents if necessary. Almost 70%
74
J: Morrison Smith
of the children were aged five and six years or 15 and 16 years. The remainder were children who were absent when their turn came for examination in these age groups. Fewer examinations are now carried out compared with 20 years ago, and coverage of the whole population is difficult owing to staff shortages.
mainly routine school
RESULTS
In the, present study 12 733 children were included and their race and place of birth is shown in Table I. There were 6562 boys, 6171 girls. The sample represents 3.56% of children at school in 1974 but over 12 o/o of those aged five and six years and 15 and 16 years. There was a highly significant (PC 0.005) rise in the prevalence of asthma and wheezing between 19567 and 1968-9 (Table II). The double questioning in relation
Table
I.
Children
Race
included
European Negro Asian Negro Asian Others Total
Table
Year 1956-7 1968-9 1974-5
Total 49 273 20 958 12 733
II.
Active
European 49 273 19 033 10 171
of
Place
in study,
197&S
birth
No.
England England England Abroad Abroad
symptoms
found
Total
(%) 2.3 2.63
10 171 1144 852 219 324 23 12 733
in three
prevalence
Asthma European 2.3 2.73
(%)
studies Asthma and wheezing Total (%) European 1.76 5.4 6.34
(%)
1.76 5.5 6.32
to asthma and wheezing in 1968-9 could have increased the number of positive responses but there was still a significant increase between all asthma and wheezing in 1956-7 and asthma only in 1968-9 (P=O.O5). Between 1968-9 and 1974-5 the increase for asthma was significant (P= 0.05) and for asthma plus wheezing highly significant (P< 0.005). Th ese findings were not altered by the increasing proportion of children or their parents who had been born abroad, from 6.8 y. in 1968-9 to 20 y. in 1974-5. The occurrence of symptoms in relation to race and place of birth in the last two studies is shown in Table III. Asthma and wheezing was apparently more common in Negro children born in England than in either European or Asian children and much more common than in Negro children born abroad, although this difference was less striking in the recent study than in 1968-9. In Asian children this trend is only noted in relation to asthma plus wheezing in 1974-5.
Asthma and Wheezing in Children Table III.
Active symptoms place of birth
related
75
to race and
Asthma and wheezing (%) 1968-9 1974-S European Born in England Negro Born in England Born abroad Asian Born in England Born abroad
5.5
6.32
11.6 1.5
9.09 5.02
3.4 3.4
4.22 2.84
When all children in the main immigrant groups were considered together asthma was found in 2.65 y0 of the 1996 born in England but in only 1.19 y0 of the 671 born abroad (P= 0.05). Asthma plus wheezing was found in 7.01 y0 of those born in England and in 3.13 y0 of those born abroad (PC 0.005). The effect of age and sex on the presence of symptoms was analysed in children in the two age groups which accounted for the majority of those examined (Tables IV, V and VI). Active symptoms were more common in European boys than girls, the difference in asthma being significant at both five and six years (P-c 0.01) and at 15 and 16 years (P< 0.005) and the sex difference in asthma plus wheezing was also significant in both Table IV. Active
symptoms
related to age and sex in Europeans
Both sexes Age 5 and 6 years Total Asthma Asthma and wheezing Age 15 and 16 years Total Asthma Asthma and wheezing Table V. Active
Boys
Girls
3773 2.3% 7.5%
1757 3% 9.39%
1676 1.6% 5.54%
P
THE PREVALENCE OF ASTHMA WHEEZING IN CHILDREN J. The
MORRISON
Asthma
The prevalence of asthma and wheezing in the previous studies in 1968-9 and 1956-7. period, although the rate of increase had Children of the same racial group were diseases, if born in England than if born in life profoundly influence the prevalence of
Clinic,
J. Dis.
Chest
(1976)
70, 73
AND
SMITH Birmingham
children in Birmingham in 1974-5 was compared with The frequency of asthma increased over the 20-year slowed. Asthma was commoner in boys than in girls. more prone to asthma, and probably to other atopic poor tropical countries. Environmental factors in early asthma in childhood.
INTRODUCTION
The prevalence of asthma in children in Birmingham has been studied on three separate occasions, in 1956-7 (Smith 1961), in 1968-9 (Smith et al. 1971) and in 1974-5. The results in 1968-9 suggested that asthma had increased in children in England and that factors in early life influenced the prevalence, in that children born in poor tropical countries were less likely to have asthma than children of the same race born in England. This may be true not only for asthma but also for other atopic diseases. In Birmingham eczema in Negro children who have asthma is just as common as it is in European children with asthma (Smith 1973) and hay fever is virtually unknown in persons born in tropical countries until they have lived in England for several years, although it probably occurs just as frequently in Negro and Asian children born in England as in European children. The present study was undertaken to see if asthma is still increasing in frequency and to assess differences in incidence between European and immigrant children. Methods The information was collected by school health visitors from parents at the routine school medical examinations. They were asked to enquire about already diagnosed asthma first and then about recurrent attacks of wheezing which had not been called asthma. The definitions used for asthma and wheezing and the methods and staff used in the collection of the information have been similar in the three studies. In 1956-7 there were hardly any children who had themselves been born abroad or whose parents had been born abroad, but by 1968-9 large numbers of immigrant children were included. The schools where the examinations were done were widely scattered over the city so that it is likely that they represent a reasonable cross-section of the population of Birmingham in relation to social class. Previous experience in 1956-7 had shown that recurrent wheezing attacks in children of school age are unlikely to be due to causes other than asthma, although those not called asthma by the family doctor are likely to be less severe and persistent and to carry a better prognosis than those definitely so diagnosed (Smith 1961; Smith et al. 1971). Interpreters were available for communication with Asian parents if necessary. Almost 70%
74
J: Morrison Smith
of the children were aged five and six years or 15 and 16 years. The remainder were children who were absent when their turn came for examination in these age groups. Fewer examinations are now carried out compared with 20 years ago, and coverage of the whole population is difficult owing to staff shortages.
mainly routine school
RESULTS
In the, present study 12 733 children were included and their race and place of birth is shown in Table I. There were 6562 boys, 6171 girls. The sample represents 3.56% of children at school in 1974 but over 12 o/o of those aged five and six years and 15 and 16 years. There was a highly significant (PC 0.005) rise in the prevalence of asthma and wheezing between 19567 and 1968-9 (Table II). The double questioning in relation
Table
I.
Children
Race
included
European Negro Asian Negro Asian Others Total
Table
Year 1956-7 1968-9 1974-5
Total 49 273 20 958 12 733
II.
Active
European 49 273 19 033 10 171
of
Place
in study,
197&S
birth
No.
England England England Abroad Abroad
symptoms
found
Total
(%) 2.3 2.63
10 171 1144 852 219 324 23 12 733
in three
prevalence
Asthma European 2.3 2.73
(%)
studies Asthma and wheezing Total (%) European 1.76 5.4 6.34
(%)
1.76 5.5 6.32
to asthma and wheezing in 1968-9 could have increased the number of positive responses but there was still a significant increase between all asthma and wheezing in 1956-7 and asthma only in 1968-9 (P=O.O5). Between 1968-9 and 1974-5 the increase for asthma was significant (P= 0.05) and for asthma plus wheezing highly significant (P< 0.005). Th ese findings were not altered by the increasing proportion of children or their parents who had been born abroad, from 6.8 y. in 1968-9 to 20 y. in 1974-5. The occurrence of symptoms in relation to race and place of birth in the last two studies is shown in Table III. Asthma and wheezing was apparently more common in Negro children born in England than in either European or Asian children and much more common than in Negro children born abroad, although this difference was less striking in the recent study than in 1968-9. In Asian children this trend is only noted in relation to asthma plus wheezing in 1974-5.
Asthma and Wheezing in Children Table III.
Active symptoms place of birth
related
75
to race and
Asthma and wheezing (%) 1968-9 1974-S European Born in England Negro Born in England Born abroad Asian Born in England Born abroad
5.5
6.32
11.6 1.5
9.09 5.02
3.4 3.4
4.22 2.84
When all children in the main immigrant groups were considered together asthma was found in 2.65 y0 of the 1996 born in England but in only 1.19 y0 of the 671 born abroad (P= 0.05). Asthma plus wheezing was found in 7.01 y0 of those born in England and in 3.13 y0 of those born abroad (PC 0.005). The effect of age and sex on the presence of symptoms was analysed in children in the two age groups which accounted for the majority of those examined (Tables IV, V and VI). Active symptoms were more common in European boys than girls, the difference in asthma being significant at both five and six years (P-c 0.01) and at 15 and 16 years (P< 0.005) and the sex difference in asthma plus wheezing was also significant in both Table IV. Active
symptoms
related to age and sex in Europeans
Both sexes Age 5 and 6 years Total Asthma Asthma and wheezing Age 15 and 16 years Total Asthma Asthma and wheezing Table V. Active
Boys
Girls
3773 2.3% 7.5%
1757 3% 9.39%
1676 1.6% 5.54%
P
