Prevalence of allergic rhinitis among adolescents from Distrito Federal, Brazil: comparison between ISAAC phases I and III

Abstracts

OBJETIVOS: Determinar a prevalência de rinite alérgica em um grupo aleatório de escolares de Brasília (DF), com idade entre 13-14 anos; avaliar suas tendências ao longo de 6 anos e comparar as taxas de prevalência entre diferentes grupos socioeconômicos. MÉTODOS: Dois estudos de corte transversal foram realizados com intervalo de 6 anos, usando o questionário escrito do protocolo ISAAC (fases I e III). Nesta pesquisa, 39 escolas foram escolhidas aleatoriamente, em oito regiões administrativas de Brasília, e divididas em três grupos, segundo as condições socioeconômicas da população. RESULTADOS: Foram obtidos 3.009 questionários, sendo 53,5% do sexo feminino e 80% de alunos de escolas públicas. As prevalências de rinite diagnosticada, rinite recente e rinite alérgica foram 20, 29,3 e 12,2%, respectivamente. A prevalência de rinite foi maior nas escolas privadas do que nas escolas públicas (17,8 versus 14,1%) e predominou no sexo feminino. Também foi maior nas populações de melhor nível socioeconômico (23,5 versus 12,2%). Comparando com dados de 1996, houve aumento significativo da prevalência de rinite diagnosticada (12,7 versus 20%, p = 0,001), aumento que ocorreu em todos os níveis socioeconômicos. CONCLUSÃO: Um grande número de crianças de 13 e 14 anos de idade do Distrito Federal está apresentando os sintomas relacionados à rinite, a maioria dos quais representa rinite alérgica. Em um período de 6 anos, a prevalência de rinite alérgica aumentou de maneira significativa, predominando no sexo feminino, e foi maior em crianças de escolas privadas e de nível socioeconômico mais elevado.

Rinite alérgica perene; prevalência; adolescente; análise socioeconômica

ORIGINAL ARTICLE

Prevalence of allergic rhinitis among adolescents from Distrito Federal, Brazil: comparison between ISAAC phases I and III

Wellington G. Borges^I; Dennis Alexander R. Burns^I; Maria Luísa B. M. Felizola^II; Bruno A. Oliveira^III; Cejana S. Hamu^III; Vanessa C. Freitas^III

^IPediatra e alergista/imunologista, Hospital de Base do Distrito Federal, DF, Brasil

^IIMestre. Professora, Fundação de Ensino e Pesquisa em Ciências da Saúde (FEPECS), Distrito Federal, DF, Brasil

^IIIAcadêmico de Medicina, FEPECS, Distrito Federal, DF, Brasil

^{Correspondence}

ABSTRACT

OBJECTIVES: To determine the prevalence of allergic rhinitis in a random group of schoolchildren aged 13 to 14 years in Brasilia, Brazil, to evaluate tendencies over 6 years and to compare prevalence rates among different socioeconomic groups.

METHODS: Two cross-sectional studies were undertaken 6 years apart, using the ISAAC (phases I and III) written questionnaire. Thirty-nine schools were chosen at random from eight administrative regions in Brasilia, and were classified into three groups according to the socioeconomic conditions of the population.

RESULTS: A total of 3,009 questionnaires were collected. Of these 53.5% related to female children and 80% to students from public schools. Prevalence rates for diagnosed rhinitis, recent rhinitis and allergic rhinitis were 20, 29.3 and 12.2%, respectively. Rhinitis was more prevalent in private schools than in public ones (17.8 versus 14.1%) and sufferers were predominantly female. Prevalence rates were also higher among populations with higher socioeconomic status (23.5 versus 12.2%). Comparison with the 1996 data revealed significant increases in the prevalence of diagnosed rhinitis (12.7 versus 20%, p = 0.001). These increases were observed at all socioeconomic levels.

CONCLUSION: A large number of 13 and 14-year-old children resident in the Distrito Federal exhibit symptoms indicative of rhinitis and the majority of them have allergic rhinitis.

Over a six-year period the prevalence of allergic rhinitis increased significantly, predominantly affecting females and with greater prevalence among students at private school and from families with higher socioeconomic status.

Key words: Perennial allergic rhinitis, prevalence, adolescent, analysis socioeconomic.

Introduction

Allergic rhinitis is described as one of the most common chronic diseases of childhood and, according to research undertaken in 155 cities in countries in Africa, North and South America, Asia, Australia and Europe, involving 463,80¹ 13 and 14-year-old children,1 exhibits substantial variability in prevalence rates, ranging from 1.4 to 39.7%. Furthermore, there are countless reports of rhinitis prevalence rates increasing over recent years.^2-5

Allergic rhinitis, with its intimate association with asthma, is a public health problem in many countries, leading to the need for continuous monitoring of its tendencies.

The ISAAC (International Study of Asthma and Allergies in Childhood) project was created with the objective of assessing the prevalence and evolution of asthma and allergic diseases (rhinoconjunctivitis and atopic dermatitis), by means of a standardized written questionnaire that has been translated and validated for many languages, including Portuguese.⁶ The protocol has already been employed in 56 countries, and eight cities in Brazil were studied during phase I.⁷ The objective of phase III is to evaluate the tendencies of these pathologies.⁸

The phase I questionnaire was applied in the Distrito Federal in 1996.⁹ Our objectives were to employ identical methodology to the previous study to investigate the current prevalence of allergic rhinitis in 13 and 14-year-old children resident in several different administrative regions in Brasilia (DF), to research the disease's tendencies, comparing the current data with the 1996 results and to assess the relationship between rhinitis prevalence and the socioeconomic conditions of the population studied.

The availability of these data may provide an instrument of aid to the creation of new strategies for rhinitis management.

Methods

The populations resident in Brasilia exhibit very specific characteristics. Different populations are very well defined from a socioeconomic perspective and there is a distribution pattern encompassing nearby administrative regions.

Eight of the 19 administrative regions of the Distrito Federal were randomly chosen to take part in the study. Each region was classified into one of three groups by socioeconomic status. The sample was selected by proportional distribution according to the number of students in each group. Towns were chosen by lots:⁹

Group I: n = 919 (30.5%) - Plano Piloto and Guará - highest socioeconomic status, with 82% of family incomes more than five times the minimum wage and 69% of schoolchildren at private school.

Group II: n = 1,664 (55.3%) - Taguatinga, Ceilândia, Sobradinho and Núcleo Bandeirante - intermediate socioeconomic status, with 65% of family incomes of five times the minimum wage and 17% of students attending private school.

Group III: n = 426 (14.1%) - Samambaia and São Sebastião - low socioeconomic, with 60% of family incomes less than twice the minimum wage and just 0.4% attending private school.

Data were collected during the period from July to October 2002. During phase I, data were collected throughout 1996.⁹ The standardized ISAAC questionnaire (phase III) was employed. This has been adequately described in other publications.^10,11 Thirty-nine schools were randomly selected, in common with the 1996 study (phase I).⁹ Information on their characteristics and locations were obtained from the Distrito Federal Education Department.

The prevalence of diagnosed or reported allergic rhinitis was determined based on answers to the question, "have you ever had hayfever?" The question, "In the past 12 months, have you had a problem with sneezing, or a runny, or blocked nose?" identified those adolescents suffering from rhinitis at the time of data collection, and, in conjunction with the question, "has this nose problem been accompanied by itchy-watery eyes", identified allergic rhinitis. The severity of symptoms was assessed based on answers to the question "how much did this nose problem interfere with your daily activities?" (Figure 1).

Data analysis

Data were input to a data analysis program (Epi-Info 2002) provided by ISAAC, and compared with the data from phase I,⁹ which were obtained using identical sampling and methodology.

The statistical significance of differences between the two datasets and between different socioeconomic groups was tested by applying the chi-square test. Results were considered significant at p < 0.05.

Results

Questionnaires were completed by 3,131 children aged 13 or 14 years (53.5% were female), in the classroom under the supervision of a member of the research team.

One hundred and twenty-two of the questionnaires had to be discarded, but 3,009 (96.1%) had been correctly completed. Eighty percent of the valid questionnaires came from public schools.

The proportions of affirmative answers to each of the questions are listed in Table 1.

The prevalence of nasal symptoms ("Have you ever had a problem with sneezing, or a runny, or blocked nose?") was very high in this population (42.7%), while 29.3% reported suffering symptoms during the previous 12 months (current rhinitis sufferers). When only individuals who had ocular symptoms concomitantly are selected, this prevalence drops to 12.3% (allergic rhinitis).

Nasal symptoms were intense enough to interfere with the day-to-day activities of just 4.3 % of adolescents. Another 16.8% reported that they were not badly affected by their symptoms. An even larger number of children had nasal symptoms that did not interfere with their lives (22.7%).

Monthly variation followed a perennial pattern, with peaks during June, July and August, which are winter months in Brazil (Figure 2).

The prevalence of diagnosed rhinitis ("have you ever had hayfever") was 20%, being significantly higher among females (12.3% compared with 7.8% of males, p < 0.001, M/F ratio = 0.63). The prevalence of current rhinitis was significantly higher than diagnosed rhinitis (29.3 against 20%, p < 0.001).

Compared with the 1996 research data, a significant increase was observed in the prevalence rates of diagnosed rhinitis (from 12.7 to 20%, p = 0.001), without significant alteration in the prevalence of current rhinitis (30.2 to 29.3%, p = 0.46). Furthermore, a significantly greater number of children reported that their activities were not disturbed by their nasal problems (from 12.4 to 22.7%, p = 0.001). In contrast, the number of individuals reporting moderate worsening of symptoms increased (from 1.6 to 3.2%, p = 0.001, Table 1).

Significant alterations were observed to other items investigated by the two studies. There was a significant increase in the prevalence of symptoms during June, July and August, but there were not reductions during February, November or December (p < 0.05).

When analyzed from a socioeconomic perspective, the prevalence of diagnosed rhinitis was higher among groups with greater purchasing power (G1 > G2 > G3), and these differences were significant for G1 versus G2 (p = 0.045), G1 versus G3 (p = 0.001) and G2 versus G3 (p = 0.002). The prevalence of current rhinitis was also higher in the groups with higher socioeconomic status (G1 > G2 > G3), and differences were significant for G1 versus G2 (p = 0.03) and G2 versus G3 (p = 0.005), but not for G1 versus G3 (p = 0.101, Table 2).

There are indications that the severity of symptoms had reduced in all groups. Conjunctivitis was reported in a similar manner by all three groups (Table 2).

When we compared the phase I to the phase III data we observed that there had been a significant increase in the prevalence of reported rhinitis at all socioeconomic levels. However, analyses of the current prevalence rates of rhinitis and conjunctivitis revealed that no variation had occurred (Table 3).

The prevalence of diagnosed rhinitis was significantly higher in private than in public schools (26.8 versus 18.4%, p = 0.001). Diagnosed rhinitis was reported in association with asthma by 27.7% of the children, while 23.5% reported an association with eczema. The occurrence of all three pathologies (asthma, allergic rhinitis and eczema) simultaneously was reported by just 8.8% of the children. In contrast, just 11.1% of those who did not have rhinitis reported asthma. Current rhinitis was reported by 79.9% of the children with ocular symptoms.

Discussion

Employing the ISAAC protocol we have demonstrated that the prevalence of rhinitis in 13 and 14-year-old children in Brasilia has increased significantly over a six-year period. We have also demonstrated that populations with higher socioeconomic status suffer more from this disease.

For several years the ISAAC questionnaire has been used all over the world and has proven itself useful for assessing the prevalence and morbidity of asthma and allergic diseases. It is an easy-to-apply questionnaire that can be completed quickly without interfering with school activities.

The first study carried out in Latin America using this protocol, (phase I) took place in São Paulo, and after that six research projects were run in other Brazilian cities, investigating a total of 20,587 adolescents aged 13-14 years. According to the authors, the mean prevalence of diagnosed rhinitis was 34.2%, and the mean prevalence of allergic rhinitis was 18%.¹²

According to many research projects applying the phase III ISAAC protocol, the prevalence of allergic rhinitis has been increasing in some countries.^2-5 In Brazil the mean prevalence of rhinitis was 16.8%.¹³ No changes were detected in Porto Alegre, Salvador or São Paulo, but increases were observed in Curitiba and Recife. Our phase III research in the Distrito Federal has shown that the prevalence rates of diagnosed rhinitis (20%) and of current rhinitis (29.3%) were both above the national average, and a significant increase was recorded over the six-year period, following the global tendency.

In common with other studies undertaken in South Africa¹⁴ and in Brazil,¹⁵ we found that the prevalence of allergic rhinitis was higher among patients living under better socioeconomic conditions. Our data are in agreement with data obtained in epidemiological studies of asthma, such as that carried out by Britto et al. in Recife, reporting a higher prevalence of asthma in private schools and among children whose parents had spent longer in education.¹⁶

One concern when a research project is based on the answers given to written questionnaires is the ability of the population studied to understand the questions and to provide adequate responses. This is one possible explanation for the prevalence of diagnosed rhinitis being significantly higher at private schools and in the socioeconomic groups with higher status. In addition to cultural factors, the fact that financially more privileged groups have easier access to healthcare services may be responsible for this elevated prevalence.

The severity of rhinitis appears to have reduced since 1996, to the extent that a larger number of adolescents reported that their activities were not disturbed by their nasal symptoms. This could be due to the fact that treatment is increasingly common in our region, although this factor was not investigated by our research. In common with what we observed in phase I, the three different socioeconomic groups had similar levels of rhinitis severity. Furthermore, deterioration was observed in one of the items of rhinitis severity (moderate interference with activities) for the two highest socioeconomic status groups, in contrast with the elevated number of children who reported lesser severity.

A higher prevalence was observed for current rhinitis (sneezing, or a runny, or blocked noses in the past 12 months) than of diagnosed rhinitis (have you ever had hayfever?). We believe that underdiagnosis is the cause of the predominance of current rhinitis, as has been mentioned in the case of asthma.^17,18

We observed a predominance of females among the children with rhinitis, which is in agreement with other publications.^19,20

The seasonal variation of allergic rhinitis with increased prevalence during the winter has also been reported.^21,22

The high prevalence of rhinitis among children with ocular symptoms confirms the intimate relationship between rhinitis and allergic conjunctivitis.

In conclusion, the application of identical methodology by two different research teams to similar populations at an interval of 6 years, together with the representative samples, allows us to believe that we have evaluated the tendencies of allergic rhinitis prevalence rates, with a high degree of reliability, among 13 and 14-year-old schoolchildren in the Distrito Federal.

The data indicate a significant increase in the prevalence of allergic rhinitis. Furthermore, we found that its morbidity was greater among groups living under more favorable economic conditions and also among females.

References

Manuscript received Aug 29 2005, accepted for publication Jan 04 2006.

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Publication Dates

• Publication in this collection
  12 June 2006
• Date of issue
  Apr 2006

History

• Accepted
  04 Jan 2006
• Received
  29 Aug 2005