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Abstract
OBJECTIVES To describe the prevalence of atopic symptoms in children throughout the UK.
METHOD A questionnaire survey of 12–14 year olds throughout England, Wales, Scotland, and the Scottish Islands using the international study of asthma and allergies in childhood (ISAAC) protocol.
RESULTS A total of 27 507 (86%) children took part. Recent rhinoconjunctivitis was reported by 18.2%, with 6.2% reporting symptoms between March and September; 16.4% reported itchy flexural rash in the past 12 months. The prevalence of atopic symptoms was higher in girls and subjects born within the UK. The prevalence of severe wheeze was highest in subjects reporting perennial rhinoconjunctivitis, as opposed to summertime only symptoms. Winter rhinoconjunctivitis was associated with severe wheeze and severe flexural rash. One or more current symptoms were reported by 47.6% of all children and 4% reported all three symptoms.
CONCLUSION In general, geographical variations were small but the prevalence of symptoms was significantly higher in Scotland and northern England. The study demonstrates the importance of atopic diseases both in their own right and in association with asthma.
- international study of asthma and allergies in childhood
- hay fever
- eczema
- epidemiology
- atopic disease
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The prevalence of childhood hay fever shows wide variation throughout the world, ranging from 1.4% to 39.7%.1 The literature suggests that the prevalence of atopy has increased throughout the UK over the past five decades. In terms of eczema, the national British birth cohort study showed a rise in prevalence from 5.1% in 6 year olds born in 1946 to 12.2% for children born in 1970 and assessed at 5 years of age,2 whereas data from the Welsh study of 12 year olds by Burr et alshowed a rise from 5% in 1973 to 16% in 1988.3Similarly, the prevalence of hay fever in the same Welsh study rose from 9% to 15% over the 15 year period, whereas for Scottish children Russell reported a rise over a 25 year period from 3.2% in 1964 to 12.7% in 1994.4 5 Ross and Fleming examined general practice data, which showed that the prevalence of hay fever was maximal in the age group 5–14 years and did not show any significant differences in geographical distribution throughout England or Wales.6
Prevalence studies in different geographical areas are often difficult to compare because of variations in methodology. In addition, the term atopy, meaning a predisposition to develop type I hypersensitivity demonstrated by skin prick testing and assay of IgE, is often used in relation to atopic diseases such as hay fever and eczema. Many of these difficulties have been overcome by the protocol developed for the international study of asthma and allergies in childhood (ISAAC), which standardises both methodology and terminology. The distribution of hay fever and eczema are of interest not only in their own right, but also as an indicator of the pattern of atopy, which contributes to the burden of asthma. The literature demonstrates a strong association between asthma, hay fever, and eczema7; however, the inter-relation between atopy, atopic disease, asthma, and wheeze is somewhat complex. The presence of atopy, particularly if early in onset, predicts the later development of asthma and bronchial hyper-responsiveness, which continues into late childhood.8 9 In addition, bronchial hyper-responsiveness and reduced lung function predict persistence of wheeze and level of bronchial responsiveness in adult life.10 Warner suggests a unifying hypothesis linking atopy, bronchial hyper-responsiveness, and airway inflammation, which together with genetic predisposition and environmental influences produce asthma.11
Atopic diseases in childhood give rise to considerable morbidity and health care costs,12 13 with varying environmental influences being implicated in the rising prevalence. Studies have reported the association of hay fever and eczema with race, social class, and month of birth.14-16 The effect of outdoor or indoor air pollution on these disorders is inconsistent.17 18 The lower prevalence of allergic diseases in Leipzig compared with Munich suggests aetiological factors that are associated with Western lifestyle and living conditions.18
We report the regional variations in the prevalence and treatment of symptoms of hay fever and eczema throughout the UK and their association with sex, birthplace, wheeze, and asthma.
Methods
Subjects aged between 12 and 14 throughout England, Wales, and Scotland, including the Shetland Isles, Orkney, and the Western Isles, were invited to complete a questionnaire during the months of March and April in accordance with the ISAAC protocol.19 A sampling frame was prepared of mixed sex, state secondary schools with over 100 pupils in each school year for every county/region in the UK. In addition, randomly sampled districts from four of the six metropolitan counties were included, together with Glasgow, Edinburgh, and eight randomly selected London boroughs. One school was randomly selected from each sampling frame and all children in school years 8–9 (England and Wales) and S2–3 (Scotland), including those aged 12, were surveyed. Details of the method have been described previously,20 and the core questions are presented in appendix . Results were analysed by cross tabulation, using SAS and Clinstat statistical packages.
Ethics approval was obtained from all the relevant local committees throughout the entire UK.
Results
The response rate to the self completed questionnaires was 85.9%. Replies were received from 27 507 subjects, attending 93 secondary schools throughout England, Wales, and Scotland; 49.2% were boys and 50.8% were girls. Subjects were aged between 12 and 14, with respondents being on average 6 months older in Scotland than in England and Wales, as a result of the different school entry system.
Missing values for any one question did not exceed 4%. Therefore, denominators for prevalence vary to a small degree between tables.
PREVALENCE OF LIFETIME ATOPY, REPORTED SYMPTOMS, AND TREATMENT
Eczema
The reported lifetime prevalence of eczema was 22.5% (6189 of 27 507). Of the 16.4% (4524 of 27 507) with an intermittent itchy flexural rash occurring in the past 12 months (answered yes to questions 27 and 28 in appendix ), 49.7% (2248 of 4524) reported a previous label of eczema and 61.2% (2769 of 4524) reported treating the rash. Only 2.2% (606 of 27 507) reported a severe troublesome rash causing sleep disturbance for one night or more each week in the past 12 months, of which 56.3% (341 of 606) reported a label of eczema and 73.9% (448 of 606) had treatment.
Table 1 gives results by geographical area. The prevalence for reported symptoms was not significantly different in England compared with Wales or Scotland. However, within England there are significant differences between quadrants for the prevalence of intermittent and severe itchy flexural rash within the past 12 months (p < 0.05, χ2test of heterogeneity). In contrast, a label of eczema was reported more often in England than in Scotland (odds ratio (OR), 1.16; p < 0.001; 95% confidence interval (CI), 1.07 to 1.25) and in non-metropolitan compared with metropolitan areas (OR, 1.13; p < 0.001; 95% CI, 1.07 to 1.20).
Prevalence of reported current flexural rash symptoms, treatment, and lifetime eczema by geographical area in 12–14 year olds across the UK
Hay fever
Of the total study population, 34.9% (9610 of 27 507) reported hay fever at any time in their life and 37.9% reported rhinitis symptoms in the past 12 months.
The UK prevalence of rhinoconjunctivitis, as defined by nasal symptoms in the past 12 months accompanied by itchy watery eyes (answers yes to questions 20 and 21 in appendix ), was 18.2% (5019 of 27 507). Of the 5019 with rhinoconjunctivitis, 100 (2.0%) omitted the question about which months their symptoms occurred but over one third (37.8%; n = 1902) confirmed that it occurred perennially; a further third (34.1%; n = 1710) reported symptoms only from March to September and a quarter (26.0%; n = 1307) reported symptoms from October to February only.
Of the 18.2% (5019 of 27 507) of subjects with symptoms of rhinoconjunctivitis, 63.1% (3166 of 5019) reported hay fever and 54.2% (2720 of 5019) had received treatment. A total of 21.6% (5943 of 27 507) reported that the rhinitis symptoms interfered with their daily activities only a little, but 1.5% (417 of 27 507) reported a lot of interference.
Table 2 shows the results by geographical area. The prevalence of rhinoconjunctivitis in the past 12 months was significantly higher in Scotland than in England (OR, 1.18; p < 0.001; 95% CI, 1.08 to 1.28). In contrast, subjects in England were more likely to report a previous label of hay fever than subjects in Scotland (OR, 1.11; p < 0.003; 95% CI, 1.03 to 1.19) and be taking treatment for their related rhinitis symptoms (OR, 1.13; p < 0.001; 95% CI, 1.05 to 1.21).
Prevalence of reported current rhinoconjunctivitis symptoms, treatment for rhinitis symptoms, and lifetime hay fever in 12–14 year olds across the UK
AGE, SEX, BIRTH PLACE, AND MONTH OF BIRTH
Symptom prevalences were not significantly different within the narrow age range studied (tables 3 and 4).
Prevalence of reported flexural rash symptoms and treatment in the past 12 months and lifetime eczema: impact of age, sex, birthplace, and wheeze in the past 12 months
Prevalence of reported rhinoconjunctivitis symptoms and treatment in the past 12 months and lifetime hay fever: impact of age, sex, birth in UK, and wheeze in the past 12 months
Girls reported symptoms more often than boys—for example, itchy flexural rash (OR, 1.74; p < 0.001; 95% CI, 1.63 to 1.86) and rhinoconjunctivitis (OR, 1.40; p < 0.001; 95% CI, 1.32 to 1.49). Children born within the UK also reported symptoms more often than children born abroad—for example, itchy flexural rash (OR, 1.23; p = 0.023; 95% CI, 1.02 to 1.48) and rhinoconjunctivitis (OR, 1.20; p = 0.033; 95% CI, 1.01 to 1.43). There was no significant difference in either condition in relation to month of birth (p > 0.05) (data not shown).
ASSOCIATION OF ATOPY WITH WHEEZE SYMPTOMS
Table 5 shows the results for the prevalence of allergic diseases in relation to the season of reporting rhinoconjunctivitis symptoms.
Symptoms of rhinoconjunctivitis in relation to wheeze attacks and itchy flexural rash (percentage of children)
The prevalence of severe wheezing was higher in subjects reporting perennial rhinoconjunctivitis than in those with summer only symptoms (OR, 1.72; p < 0.0001; 95% CI, 1.34 to 2.21) and similarly for the prevalence of severe flexural rash (OR, 2.53; p < 0.0001; 95% CI, 1.84 to 3.48).
In addition, winter rhinoconjunctivitis symptoms alone are predictive of other allergic diseases; that is, severe wheeze (OR, 2.05; p < 0.0001; 95% CI, 1.51 to 2.78) and severe flexural rash (OR, 3.63; p < 0.0001; 95% CI, 2.73 to 4.82).
Figure 1 illustrates the inter-relation between reported current symptoms of flexural rash, rhinoconjunctivitis, and wheeze. Of those reporting current wheezing, 43.3% (3965 of 9155) also had current symptoms of other atopic diseases, leaving 53.7% (4919 of 9155) reporting current wheeze alone. For the 18.2% with rhinoconjunctivitis and 16.4% with an itchy flexural rash, 66.5% (3338 of 5019) and 62.1% (2809 of 4524), respectively, reported symptoms of other atopic diseases.
Prevalence of symptoms of atopic diseases within the past 12 months in 27 507 12–14 year old children across the UK in 1994–5. Overall, 47.6% of the children reported one or more symptoms of wheeze, rhinoconjunctivitis, or flexural rash. One, two, or all three symptoms were reported by 31.2%, 12.4%, and 4.0% of children, respectively. Wheezing was the most commonly reported symptom, affecting 33.3%.
Figure 2 shows the overlap between reported lifetime occurrence of eczema, hay fever, and asthma. In contrast with the symptom Venn diagram, 65.4% (3751 of 5736) of those with asthma reported having another atopic disease, 54.5% (3129 of 5736) reporting hay fever and 34.3% (1968 of 5736) reporting eczema. Of children with asthma, 29.8% (1709 of 5736) had no associated atopic diseases and 4.8% (276 of 5736) had incomplete data on eczema and hay fever.
Lifetime prevalence of reported atopic diseases in 27 507 12–14 year old children across the UK in 1994–5. Overall, 53.96% of the children reported ever having one or more of the atopic diseases. Of these, 34.4%, 14.6%, and 4.9% report ever having one, two, or all three of the atopic diseases, respectively. In contrast to current symptoms, hay fever is the most common lifetime atopic disease in the UK, reported by 34.9%, followed by eczema (22.5%) and then asthma (20.9%).
Tables 4 and 5 illustrate the significantly higher reporting of symptoms and treatment of atopic disorders in wheezers compared with non-wheezers.
Discussion
LIFETIME PREVALENCE, SYMPTOMS, AND TREATMENT
Our results for reported eczema and hay fever are higher than previously reported studies in the UK, Wales, and Scotland,3 4 21 but interpretation should be cautious when comparing parent reported study results with pupil completed questionnaires. The general nature of the questions may also be a contributory factor, and objective testing was not included to differentiate between allergic and viral components of rhinitis. However, the questionnaire has been validated previously, with the combination of itchy eyes in addition to nasal symptoms being found to be most closely related to objective indicators of allergic sensitisation.22 The UK prevalence of eczema and hay fever symptoms was less than the number reporting recent treatment, suggesting that, as expected, many children were receiving medication for non-eczematous rashes and non-allergic nasal symptoms, such as colds. Season of response has been shown to bias rhinitis but not eczema or most asthma symptom questions. Stewart et al reported the highest rhinitis prevalence in surveys carried out in the spring/early summer, with the lowest figures during winter surveys.23 Our study was carried out in March/April, before the start of the pollen season, as recommended in the ISAAC protocol.
Oranje states that eczema is a term often used incorrectly.24 Therefore, it is important in epidemiological studies to define the terminology used in questionnaires. Hence, we have described symptoms as well as reported diagnosis.
GEOGRAPHICAL VARIATIONS
The study by Åberg et al showed a higher prevalence of asthma in children living in the colder north of Sweden than in the rest of the country.25 Our results showed a higher prevalence of symptoms in the north compared with the south of the UK, with the March temperatures for the study period in 1995 being 7.1°C in south west England, Torquay, compared with 4.3°C in Inverness and 2.9°C in Shetland.26
Given the association between atopy and wheeze, our results are also consistent with the previous ISAAC UK paper that reported a higher prevalence of wheeze symptoms in Scotland than in England and Wales.20
The reverse differences in figures between Scotland and England for reported symptoms of hay fever and recent treatment of nasal symptoms may be a reflection of socioeconomic factors and differing medical practices. We are not aware of how many children actually saw a doctor or who self diagnosed and treated themselves. Some differences may be the result of chance, in view of the number of parameters analysed.
SEX, AGE, PLACE OF BIRTH, SOCIAL CLASS, AND MONTH OF BIRTH
Although previous studies show a higher incidence of atopy in boys compared with girls aged 12, Anderson suggests that by 16 years the sex ratio reverses.27 Our data suggest that this reverse ratio may be present as early as 12–14 years of age. The Swedish study of 14 year olds by Norrman et al showed that the most important risk factors for asthma were being a girl and having atopy,28 a view supported by these data.
Morrison Smith’s study of Birmingham schoolchildren showed that those born outside the UK had significantly lower prevalence of asthma and wheezing than those born in England, whereas Hurryet al found that children born in Australia had a higher prevalence of atopy than foreign born children, suggesting that environmental factors in early life have an important role in understanding atopy.29 30 Our results are consistent with this view.
Morrison Smith and Springett showed no seasonal variation in the month of birth for pollen sensitive subjects although, as a group, children with asthma showed a difference in month of birth pattern from the general population.31 Anderson reviewed several population studies that examined the relation between respiratory symptoms, eczema, hay fever, and month of birth and concluded that the findings were inconsistent.32 Our results also showed no association between itchy rash, rhinoconjunctivitis, and month of birth.
ASSOCIATION OF ATOPIC DISEASES WITH WHEEZY SYMPTOMS AND ASTHMA
Our study clearly demonstrates the inter-relation between wheeze and atopic disease. Remes reported rhinitis in 56% of children with asthma, and atopic dermatitis in 58% of children with asthma,33 which is consistent with our results for reported diagnosis of hay fever, but higher than our results in other respects. The importance of this relation was demonstrated by Kokkonen and Linna, who showed that atopic dermatitis and frequent wheezing at school age were significant risk factors for severe asthma outcome as a young adult.34 In a follow up study, Linnaet al showed that asthma and wheeze developed more often in those with perennial rhinitis than in subjects with seasonal allergic symptoms,35 which is consistent with our data. It is also interesting to note that we report an association between winter rhinoconjunctivitis symptoms and frequent wheeze or severe eczema, even among children with no summertime rhinoconjunctivitis. This suggests that the ISAAC questions relating to nose problems in the absence of a cold or influenza have some validity as indicators of allergic rhinitis, rather than infectious rhinitis, particularly when used (as in our study) in combination with reports of itchy eyes.
In view of the prognostic implications, the high percentage of adolescents reporting one or more atopic diseases, together with the high percentage of non-atopic wheezers, clearly demonstrates the importance of atopy both from an epidemiological and a clinical viewpoint. Further exploration is required to establish a possible clinical and aetiological differentiation between atopic and non-atopic wheezers and subjects with asthma.
CONCLUSION
The results demonstrate a high prevalence of atopic conditions throughout the UK. Nearly half the childhood population studied was affected by symptoms in some way and nearly one fifth reported more than one diagnosis. This highlights the importance of atopic diseases in children, both in their own right and in association with wheezy illness and asthma.
Acknowledgments
We thank the National Asthma Campaign for funding; the Departments of Education in England, Wales, and Scotland for providing data on schools; the directors of public health for confirming details of local ethics committees; ethics committees for approving the study protocol; the field workers who assisted with data collection and coding; and the head teachers, teachers, and pupils at the 93 schools.
NOSE
The following questions are about nose problems which occur when you DO NOT have a cold or the flu.
19. Have youever had a problem with sneezing, or a runny, or blocked nose when you DID NOT have a cold or the flu? Yes/No
If you answered “No” please skip to question 24
20. In the last 12 months, have you had a problem with sneezing, or a runny, or blocked nose when you DID NOT have a cold or the flu? Yes/No
If you answered “No” please skip to question 24
21. In the last 12 months, has this nose problem been accompanied by itchy-watery eyes? Yes/No
22. In which of thelast 12 months did this nose problem occur?
(Please tick any months which apply)
January; February; March; April; May; June; July; August; September; October; November; December
23. In the last 12 months, how much did this nose problem interfere with your daily activities?
Not at all A little A moderate amount A lot
24. Have youever had hay fever? Yes/No
25. In the last 12 months, have you taken any treatment (medicines or sprays) for a runny or blocked nose problem or hay fever? Yes/No
SKIN
These questions are about skin conditions:
26. Have youever had an itchy rash which was coming and going for at least six months? Yes/No
If you have answered “No” please skip to question 31
27. Have you hadthis itchy rash at any time in the last 12 months? Yes/No
If you have answered “No” please skip to question 31
28. Has thisitchy rash at any time affected any of the following places:
the folds of the elbows, behind the knees, in front of the ankles, under the buttocks, or around the neck, ears or eyes? Yes/No
29. Has thisrash cleared completely at any time during the last 12 months? Yes/No
30. In the last 12 months, how often, on average, have you been kept awake at night by this itchy rash?
Never in the last 12 months; Less than one night per week; One or more nights per week
31. Have youever had eczema? Yes/No
32. In the past 12 months, have you taken any treatment (medicines, creams, ointments) for an itchy rash or eczema? Yes/No