Prevalence, symptomatology and factors associated with asthma in adolescents aged 13–14 years from rural Sri Lanka: an analytical cross-sectional study

Introduction

Asthma is a chronic inflammatory disease of the airways that affects over 300 million people worldwide and is the most prevalent chronic condition in children.1 2 Asthma manifests in varying degrees of severity ranging from mild to severe. The severe form of asthma accounts for a substantial proportion of the overall disease burden and half of the asthma-related costs.1 The International Study of Asthma and Allergies in Childhood (ISAAC) study revealed a rise in asthma symptoms in various regions globally, including Asia.3 Southeast Asian countries have been identified as having a prevalence of asthma ranging between 29% and 32%.4 Despite the higher prevalence of asthma symptoms in many high-income countries, severe asthma is more prevalent in low-income and middle-income countries.2 The lower prevalence of asthma in developing countries is probably attributable to underdiagnosis than a true low prevalence.5 Insufficient awareness of the symptoms of asthma, even in asthmatics with frequent episodes, poor health-seeking behaviour and inadequate diagnostic facilities for asthma may contribute to the underdiagnosis.6 In the absence of a cure, asthma management is based on achieving optimal control of asthma symptoms and minimising future risk of adverse outcomes.7 Asthma control is defined as the extent to which asthma symptoms have been reduced by treatment. It depends on the availability of appropriate healthcare, adherence to treatment, environmental conditions and socioeconomic factors.8 9 Uncontrolled asthma decreases the quality of life and adversely affects healthcare utilisation.10

Adolescence is a transition period with significant physical, emotional and social changes. Asthma and its management affect adolescents in specific ways different from children and adults.11 Adolescents have to balance their academic demands, relationships and the desire for autonomy within the context of illness management, and adolescents with asthma have a greater risk of having anxiety or depression compared with healthy peers.12

Asthma is one of the most identified illnesses among school students in Sri Lanka and it causes significant school absenteeism.13 Despite the challenges adolescents with asthma face, the epidemiology and the impact of asthma on adolescents are inadequately discussed in the Sri Lankan context. Therefore, this study was conducted to assess the prevalence, associated factors and symptomatology of asthma among 13–14 year-old adolescents from a town in rural Sri Lanka.

Results

The study sample consisted of 1029 participants with 528 (51.3%) boys and 501 (48.7%) girls. The mean age was 13.2 years with 826 (80.3%) aged 13 years and 203 (19.7%) aged 14 years. Most of the study participants (931, 90.5%) were born in Anuradhapura district, Sri Lanka. The prevalence of wheeze ever and current wheeze was 32.6% (n=335) and 23.7% (n=244), respectively (table 1). Dry cough at night and wheezing during playing were reported by 345 (33.5%) and 259 (25.2%) adolescents, respectively. The prevalence of parent-reported physician-diagnosed asthma was 19.0% (n=196; 95% CI 16.7 to 21.6). Severe asthma was reported by 157 (15.3%; 95% CI 13.1 to 17.6) adolescents.

The association of demographic factors, housing conditions, dietary habits and playing habits with severe asthma is shown in table 2. The independent factors associated with severe asthma were sleeping on cloth on the floor (p<0.02, adjusted OR 9.72; 95% CI 1.56 to 60.78) (n=4 out of 6), cooking using sawdust (p=0.04, adjusted OR 8.71; 95% CI 1.10 to 68.69) (n=3 out of 5), eczema (p<0.01; adjusted OR 7.39; 95% CI 3.34 to 16.39) (n=18 out of 33) and allergic rhinitis (p<0.01; adjusted OR 5.50; 95% CI 3.80 to 7.98) (n=91 out of 266). Having a cemented floor in the house (p<0.04; adjusted OR 0.68; 95% CI 0.47 to 0.99) was a protective factor. The most common roofing material used was asbestos sheets in this population (n=752, 74.7%). However, roofing was not associated with severe asthma (p>0.26). The frequent use of incense burners or mosquito coils inside the house was not associated with severe asthma (p>0.46).

The ACT was completed by 97 (61.8%) severe asthmatics (table 3). The mean asthma control score was 20.5 (±3.3), ranging from 13 to 25 (figure 1). Poor control of asthma symptoms was detected in 29 (29.9%) adolescents. Comorbid allergic rhinitis was associated with poor control of asthma symptoms (p<0.01; unadjusted OR 5.40; 95% CI 1.84 to 15.82). Other evaluated demographic, housing, domestic, activity and dietary factors were not significantly associated with poor control of asthma symptoms (p>0.05).

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Discussion

This study found that almost one out of the four adolescents aged 13–14 years in the Anuradhapura municipal council area (23.7%) had current wheeze, and 15.3% had severe asthma. Severe asthma was independently associated with allergic rhinitis, eczema, cooking using sawdust as fuel and sleeping on a cloth instead of a mattress. Living in a house with a cemented floor was a protective factor. Poor asthma control was found in 29.9% of severe asthmatics with an independent association with comorbid allergic rhinitis.

The current wheeze prevalence reported in Kandy (15.3%) and Anuradhapura (14.9%) districts among 13–14 year-old adolescents was significantly lower (p<0.01) than the current study.19 The current study was conducted in schools located in the municipal council area which may be reflected in the higher prevalence of current wheeze. However, the prevalence of current wheeze and current asthma in the Gampaha district—the second most populous district in Sri Lanka consisting of highly urbanised, moderately urbanised and rural sections—were significantly lower than the present study (16.7% (p<0.001) and 10.7% (p=0.049), respectively).9 This significantly higher prevalence warrants further exploration of contributory factors. The Global Asthma Network Phase I study conducted in the urban areas of India including 25 887 adolescents aged 13–14 years reported a significantly lower prevalence of current wheeze (3.63%, p<0.001) and severe asthma prevalence (1.60%, p<0.001).20 Similarly, the self-reported physician-diagnosed asthma prevalence in the present study is significantly higher compared with the previously known prevalence in the Gampaha district (14.5%, p=0.002) and urban centres in India (2.32%, p<0.001). According to phase III of the ISAAC study conducted among 13–14 year-old adolescents, the global, Indian subcontinent and Sri Lankan prevalence of current wheeze were detected to be 13.7%, 6.4% and 23.0%, respectively.21 22 The 23.7% prevalence of current wheeze noted in this study was comparable with the national reports of the ISAAC study.

The well-known independent association of asthma with allergic rhinitis and eczema was also observed in this study. The other independently associated factors were cooking using sawdust as a fuel and sleeping on a cloth on the floor. There is ample evidence demonstrating the occupational hazard of exposure to sawdust.23 Therefore, adolescents exposed to sawdust used as a cooking fuel are more likely to develop severe asthma. The number of adolescents from households using sawdust for cooking is limited in the current study. This association should be further investigated in communities where using sawdust as a cooking fuel is a common practice. The association of sleeping on a cloth on the floor with allergic rhinitis was observed in preschool children from the Anuradhapura district.24 Sleeping on the floor increases the risk of exposure to dust and house dust mites, a known risk factor for asthma.25 However, the confounding effect of factors associated with poor economic conditions cannot be excluded. Having cemented flooring was a protective factor against severe asthma, probably attributable to the easily cleanable nature preventing dust accumulation.26

ACT is a widely used tool to assess asthma control and poor control of asthma was found in almost one-third of the adolescents with severe asthma (29.9%). A study conducted in Italy showed that 23.2% of asthmatic children and adolescents had uncontrolled asthma.27 The poor control of symptoms highlights the need to provide tailored care to adolescents with severe asthma to improve their symptom control and quality of life, especially in children with comorbid allergic rhinitis.7 Current guidelines advocate achieving well-controlled asthma to have less frequent and less severe exacerbations, minimal use of rescue therapy and a better quality of life.

Conclusion

This study showed that almost one out of the four adolescents (23.7%) in this population had current wheeze, and 15.3% had severe asthma. Severe asthma was independently associated with allergic rhinitis, eczema, cooking using sawdust as fuel and sleeping on a cloth instead of a mattress. Living in a house with a cemented floor was a protective factor. Poor asthma control was found in 29.9% of severe asthmatics with an independent association with comorbid allergic rhinitis.