Exercise-induced asthma in Nepalese children

Prevalence of bronchial asthma in Indian children

BACKGROUND

The prevalence of childhood bronchial asthma and allergic disease has increased in developed countries. Studies have identified asthma among Indian children. Still, there is paucity of information on the overall prevalence of childhood asthma in India.

OBJECTIVE

To assess time trends and the overall prevalence rate of bronchial asthma among Indian children.

MATERIALS AND METHODS

Literature search for data sources was done through an extensive search in indexed literatures and website-based population survey reports. Fifteen epidemiological studies were identified on the development of asthma in Indian children from 300 potentially relevant articles. A broad criterion to define both allergic and non-allergic descriptions of asthma in Indian children was formed. Moreover, in the absence of universally accepted criteria by reporting of prevalence by researchers, weighted average data was considered during calculations of prevalence rates, irrespective of the criteria for diagnosis. Statistical analyses used were mean and median.

RESULTS

Wide differences in samples, primary outcome variables, lack of consistency in age category, rural-urban variation, criteria for positive diagnosis, and study instruments confounded the outcome variables. The mean prevalence was 7.24 +/- SD 5.42. The median prevalence was 4.75% [with IQR = 2.65 - 12.35%]. Overall weighted mean prevalence was found to be 2.74. Childhood asthma among children 13 - 14 years of age was lower than the younger children (6 - 7 years of age). Urban and male predominance with wide inter-regional variation in prevalence was observed.

CONCLUSIONS

Our findings indicate that the burden of bronchial asthma in Indian children is higher than was previously understood.

Prevalence of bronchial asthma in schoolchildren in Delhi

There is a paucity of information on the prevalence of asthma in children in India. Some evidence suggests that asthma is less common in developing than in the developed countries. The present study was carried out to estimate its current magnitude in children in Delhi. The questionnaire-based study was carried out in two randomly selected schools in Delhi. All the children were eligible. The age range was 4-17 years. The questionnaires were distributed to all the children present (n = 2867) to be answered by either parent. The key questions were related to complaints of recurrent wheezing in the past, in the last 1 year, and also wheezing exclusively induced by exercise or colds. In all, 2609 questionnaires were completed and returned (response rate 91%). There was a slight excess of males (54%). The prevalence of current asthma was 11.6% and past asthma was reported by 4.1% of children, giving a cumulative prevalence of 15.7%. Exclusive exercise-induced asthma was 2.8% and that associated with colds, 2.3%. The current prevalence of all wheezing was thus 16.7% and cumulative prevalence was 20.8%. While there was no sex-related difference in prevalence, wheezers were the highest in the 9-13 year age group. A significant association was found between the prevalence of wheezing and a family history of asthma (odds ratio 3.65) and presence of smokers in the family (odds ratio 1.62). When both the above factors combined, the odds ratio for risk of asthma was 4.58. There was no significant association with any economic class. Only 11% of asthmatics had been labeled so by their physicians. The prevalence of bronchial asthma and wheezing in children in Delhi is quite high and comparable to that reported from several developed countries. A positive family history of asthma and presence of smokers in the family emerged as significant risk factors.

Epidemiology of bronchial hyperresponsiveness

Asthma is a serious health problem, with both mortality and severity increasing in developed countries (55-57). The development of more specific tests to measure the prevalence and incidence of asthma is of paramount importance. Because measurement of BHR is the only practical objective method for assessing the abnormality of the airways in asthma, it is important to continue examining this measurement as a means of detecting asthma and to explore ways of increasing the sensitivity and specificity of the test. At present, it is clear that measurements of BHR in the community cannot be used as a marker of asthma and that the test requires careful interpretation, especially in adult populations. However, it is becoming apparent that moderate and severe levels of BHR (PD20FEV1 less than 0.8 mumol of histamine) are almost always associated with clinically important morbidity, and comparison of this BHR severity in populations may yield more information than comparison of a wider range of severity in which the associated factors are not well-defined. It is important to determine whether this range of severity of BHR is associated with long-term morbidity from asthma, and whether the use of other measurements from the dose-response curve, such as the shape or similarity of curves to different provoking agents, can increase the specificity of the test. It is also important to continue to investigate the risk factors associated with the development and occurrence of BHR so that individuals who are likely to develop BHR can be identified and, in the longer term, preventive measures can be introduced. There have been relatively few studies of the prevalence of BHR in large populations of children and adults in North America. Such studies would provide essential comparative information about apparent regional differences in both the prevalence of and the mortality from asthma.

Prevalence of childhood asthma in Taipei, Taiwan, and other Asian Pacific countries

Two epidemiological surveys of the prevalence of bronchial asthma in schoolchildren in Taipei, Taiwan, were conducted in 1974 and 1985. The same questionnaire and school, and schoolchildren of the same age (7-15 years), were studied in these two surveys. Bronchial asthma was defined as at least three paroxysmal, recurrent attacks of wheezing and dyspnea in the previous 12 months. A total of 23,678 children were studied in 1974 and 147,373 children in 1985. Data from other Asian Pacific countries were also reviewed.

THE RESULTS

1) The questionnaire was able to differentiate asthmatics from nonasthmatics on the basis of differences in methacholine challenge, intracutaneous skin testing, total eosinophil count, total serum IgE, and RAST between the two groups. 2) The prevalence of childhood asthma increased from 1.30% in 1974 to 5.07% in 1985, with boys dominating in both studies. 3) The increase in asthma prevalence could not be explained by air pollution or exposure to new allergens. 4) The prevalence of childhood asthma in the Asian Pacific countries are generally comparable to those of Western countries, and the present study and studies from Japan and New Guinea showed an increasing tendency. Thus childhood asthma is a major problem in the Asian Pacific countries as well as in Western countries.

Prevalence rates of asthma in developing countries and their comparison with those in Europe and North America

Prevalence rates for asthma in various parts of the world are different and this cannot be entirely explained by differences in methodology. Low prevalence rates are found in third world countries, particularly marked for children. The reasons for these differences are obscure but are largely environmental. Some suggestions are made herein about their nature.

Exercise and the asthmatic

Physical exercise is not hazardous to asthmatics. Some asthmatics may benefit from physical training, and almost all asthmatics can perform any kind of physical exercise. Free running was earlier thought to induce more asthma than swimming, for example; however, when ventilation is identical during running and swimming, the exercise-induced asthma will also be the same. Hyperventilation alone is as good as physical exercise to induce exercise-induced asthma. If the physical exercise provokes an asthmatic attack, this is most often easily reversed by inhaled beta 2-agonists. Pretreatment of exercise-induced asthma is most efficient by inhaled beta 2-agonist; orally dosed beta 2-agonist is not as efficient as inhaled beta 2-agonist in the pretreatment of exercise-induced asthma. Inhaled sodium cromoglycate diminishes exercise-induced asthma, and the effect seems to be better in children than in adults. Inhaled steroids have no immediate effect on exercise-induced asthma, but long term treatment with steroids diminishes exercise-induced asthma. The pathogenesis of exercise-induced asthma remains obscure. If the water content is low in the inhaled air, e.g. in cold air, the changes in ventilatory capacity following exercise. will be greater than when the exercise is performed while inhaling hot air with high humidity. Almost all asthmatics present changes in the ventilatory capacity following exercise. Seasonal changes in exercise-induced asthma are only present in asthmatics with seasonal allergies, e.g. pollen allergy. No diurnal variation is found in exercise-induced asthma. Asthmatics can do any form of physical exercise. Almost all asthmatics can prevent major changes in ventilatory capacity by pretreatment of exercise-induced asthma or be treated for exercise-induced asthma during the physical activity so that they will not suffer from asthma while performing physical exercise. Asthmatics who have been successfully treated for exercise-induced asthma can do physical exercise at the same level as non-asthmatics. Asthmatic children in particular should be encouraged to perform any sport they like, as the physiological and psychological effects may be beneficial to them. It is concluded that almost all asthmatics have exercise-induced asthma, and that physical training may be beneficial. Exercise-induced asthma is best treated and pretreated by inhalation of beta 2-agonists.

Immediate hypersensitivity, IgE and asthma

Twenty-one asthmatic and twenty-two non-asthmatic children and nine asthmatic adults from two different rural areas of Tanzania, and eight asthmatic children from Dar-es-Salaam were surveyed by questionnaires, skin testing and the measurement of serum IgE. Asthma was significantly commoner in female rural children (four males, fifteen females). The rural asthmatic children apparently had less skin reactivity (in seven of nine tests) and lower specific (in two of four tests) and total serum IgE than age-, sex- and village-matched controls. This pattern of asthma in rural children in the tropics represents a different type of asthma from that found in temperate zones. In contrast, the adult rural asthmatics and the urban children seemed to have the pattern of increased skin reactivity and serum IgE found in asthmatic patients from temperate climates.

The prevalence of immediate positive skin tests in Nepalese children

Two hundred and ninety-three normal schoolchildren between 5 and 15 years old living in the hills of Eastern Nepal were tested by the skin prick method for sensitivity to six allergens: Dermatophagoides pteronyssinus, Aspergillus fumigatus. Cladosporium herbarum, Penicillium notatum, mixed pollens and mixed threshings. These children were also questioned and examined for symptoms and signs relating to allergic disease. Of the children, 20% were skin-prick positive to at least one of the allergens, and 20% had symptoms of allergic disease, but there was no relationship between the symptoms and the prick test results. No relationship was found between the prick test results and any of the following: the length of time a child was breast-fed; the age of the child and his month of birth. Of the boys, 19% admitted to smoking cigarettes, as did 11% of the girls.