Trends in prevalence of symptoms of asthma, hay fever, and eczema in 12-14 year olds in the British Isles, 1995-2002: questionnaire survey

The prevalence of symptoms of asthma, allergic rhinitis, and atopic eczema in children in the United Kingdom ranks among the highest in the world.¹ The evidence from most repeat surveys is that prevalence has increased over the past three decades,² but the most recent of these studies observed that from 1991 to 1998 the increase was confined to milder symptoms of asthma.³ Since the early 1990s the incidence of asthma episodes presenting to general practitioners, and of hospital admissions, has fallen substantially.²

Participants, methods, and results

In 1995, as part of the international study of asthma and allergies in childhood (ISAAC), we surveyed symptoms of atopic disease in England, Scotland, Wales, and the offshore islands of Guernsey, Isle of Man, and Jersey.⁴,⁵ A self completed questionnaire which adhered to the core ISAAC protocol was administered to secondary school children aged 12-14 in school years 8 and 9 (S2 and S3 in Scotland). In 2002 the survey was repeated in Scotland, Wales, and the islands in the same school years, using the same questionnaire and procedures in the same period of the year and, mostly, in the same schools. In England, only the schools in the South East Region were surveyed a second time. The table shows the changes in prevalence over the seven years from 1995 to 2002.

Table 1.

Trends in symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema in 12-14 year olds, British Isles, 1995-2002

	South east England			Scotland*			Wales			Islands*			Total (unweighted average)
	1995	2002	Difference	1995	2002	Difference	1995	2002	Difference	1995	2002	Difference	1995	2002	Difference	% change
No of children with completed questionnaires	4516	4788		4444	4662		2351	2501		3772	3804		15 083	15 755
Participation (%)	(86)	(86)		(85)	(89)		(86)	(85)		(91)	(88)		(87)	(87)
12 month prevalence (%)
Wheeze†	30.9	26.4	−4.5	36.7	27.8	−8.9	33.6	27.5	−6.1	34.4	28.2	−6.2	33.9	27.5	−6.4	−19.0
Four or more attacks	8.6	6.1	−2.5	11.6	6.4	−5.2	9.0	6.2	−2.8	9.7	6.5	−3.2	9.7	6.3	−3.4	−35.2
Disturbance of sleep‡	3.3	2.9	−0.4	4.7	3.7	−1.0	3.7	3.7	0	3.4	3.8	0.4	3.8	3.5	−0.3	−6.6
Speech limiting attacks§	8.3	6.9	−1.4	10.0	6.7	−3.3	9.0	6.3	−2.7	8.5	7.3	−1.2	9.0	6.8	−2.2	−24.0
Rhinoconjunctivitis¶	16.3	14.7	−1.5	20.3	15.0	−5.3	18.5	12.7	−5.8	18.4	18.1	−0.3	18.4	15.1	−3.3	−17.7
Flexural rash**	16.3	10.8	−5.5	16.7	11.7	−5.0	15.3	10.6	−4.7	16.5	12.5	−4.0	16.2	11.4	−4.8	−29.6
Lifetime prevalence
Asthma	19.4	25.0	5.6	21.4	24.5	4.1	21.8	27.1	5.3	19.6	27.0	7.4	20.6	25.9	5.4	26.0
Hay fever	37.2	38.8	1.6	33.2	34.0	0.8	32.6	38.5	5.9	36.0	38.2	2.2	34.8	37.4	2.6	7.6
Eczema	22.0	25.8	3.8	20.6	24.9	3.3	21.1	23.8	2.7	20.5	22.7	2.2	21.1	24.3	3.3	15.4
Admissions for asthma††	16.2	13.2	−3.0	19.4	13.2	−6.2	21.3	16	−5.3				16.8	13.3	−3.4	−20.4

^*Scottish Islands are included in Scottish results.

^†Wheezing or whistling in the chest in the last 12 months.

^‡Disturbance of sleep due to wheezing one or more nights per week.

^§Wheezing “severe enough to limit your speech to only one or two words at a time between breaths.”

^¶Positive response to both questions: “In the past 12 months have you had a problem with a runny or blocked nose when you did not have a cold or the flu?” and “In the past 12 months, has this nose problem been accompanied by itchy-watery eyes?”

^**Positive responses to both questions: “Have you had this itchy rash at any time in the past 12 months?” and “Has this itchy rash at any time affected any of the following places: behind the knees, in front of the ankles, under the buttocks, or around the neck, ears, or eyes?”

^††Ages 10-14, per 10 000, 1995-2000, from hospital episode statistics for England and Wales and Scottish Hospital Inpatient System.

Overall, the prevalence of any wheezing or whistling in the chest in the past 12 months fell from 34% to 28% (19% relative reduction). Even larger proportional falls were observed for frequent attacks (35%) and speech limiting attacks (24%). Large reductions were also observed for symptoms of allergic rhinoconjunctivitis (16%) and atopic eczema (30%). The proportion of children reporting “ever” having had “asthma” or “eczema” increased (26% and 15%), as did the lifetime prevalence of “hay fever” (8%). Trends in the four regions were similar.

The fall in prevalence is consistent with other sources. From 1995 to 2000, hospital admissions for asthma fell by 20.4% in 10-14 year olds in England, Scotland, and Wales combined (see table). From 1995 to 2002, in 10-14 year olds in a sample of 75 English and Welsh practices, visits to a general practitioner for episodes of asthma decreased by 47% (from 38.3 to 20.4 per 1000). Recently released data from the health survey for England shows that from 1997 to 2001, the 12 month prevalence of wheezing in 10-14 year olds, based on parental reporting, fell by 18% (from 17.4% to 14.2%).

Comment

The burden of self reported asthma and other allergic diseases among adolescents has changed substantially for the better in recent years throughout the British Isles. These trends correspond to those seen in the 10-14 year age group in hospital admissions, consultations with general practitioners, and parentally reported symptoms in the health survey for England. Just as we do not know why the prevalence of symptoms of asthma has increased since the 1950s, we do not know why it should now be decreasing. The increased use of effective treatment, especially inhaled steroids, is likely to have been important in reducing the severity of episodes, but this is unlikely to explain the decrease in mild wheeze symptoms, which is more consistent with a fall in the underlying prevalence. The most likely explanation for the paradoxical increase in prevalence of the label of asthma is that it is applied to increasingly milder disease.