|Year : 2015 | Volume
| Issue : 2 | Page : 104-108
A study of the prevalence and risk factors of asthma in urban schools of Ludhiana, Punjab
Kamaldeep Arora1, Rashmi Ranjan Das2, Puneet A Pooni1, Rashi Rustagi1, Daljit Singh1
1 Department of Pediatrics, Dayanand Medical College and Hospital, Ludhiana, Punjab, India
2 Department of Pediatrics, All India Institute of Medical Sciences, Bhubaneswar, Odisha, India
|Date of Web Publication||17-Jan-2016|
Rashmi Ranjan Das
Department of Pediatrics, All India Institute of Medical Sciences, Bhubaneswar - 751 019, Odisha
Source of Support: None, Conflict of Interest: None
Background: Asthma is the most common chronic childhood disease being increasingly diagnosed in recent years. A review estimating the prevalence of bronchial asthma in the Indian children concluded the burden to be high than previously understood. There is paucity of data from Punjab, and no study from Ludhiana has estimated the true prevalence of asthma in urban area.
Objective: To determine the prevalence and risk factors for childhood asthma using questionnaires and pulmonary function tests.
Material and Methods: This was a questionnaire based cross-sectional study over a period of 1.5 year in the age group of 5-15 years studying in three schools of urban Ludhiana. The data were analyzed b STATA Software (version 16, college station Tx, USA). P < 0.05 was considered as significant.
Results: The retrieval of questionnaire I was possible in 80% of the 2500 distributed. The prevalence of asthma was calculated as 7.5% (95% confidence interval, 5.2-10.5). The mean age of the children with asthma was 8.67 2.62 years. The most common symptoms reported by the cases were wheezing and seasonal allergy. No predilection for sex, socioeconomic status, and pet at home was noted. The family history of asthma and allergy, family history of smoking were emerged as significant risk factors.
Conclusions: The prevalence of asthma in the urban schools of Ludhiana was found to be 7.5% which was much higher than previously reported. Age groups 5-8 years were commonly affected. Family history of asthma or allergy, and smoking history were found to be significant risk factors for development of asthma.
Keywords: Allergy, cross-sectional study, peak expiratory flow, questionnaire, risk factors
|How to cite this article:|
Arora K, Das RR, Pooni PA, Rustagi R, Singh D. A study of the prevalence and risk factors of asthma in urban schools of Ludhiana, Punjab. Indian J Health Sci Biomed Res 2015;8:104-8
|How to cite this URL:|
Arora K, Das RR, Pooni PA, Rustagi R, Singh D. A study of the prevalence and risk factors of asthma in urban schools of Ludhiana, Punjab. Indian J Health Sci Biomed Res [serial online] 2015 [cited 2018 Oct 15];8:104-8. Available from: http://www.ijournalhs.org/text.asp?2015/8/2/104/174237
| Introduction|| |
The median prevalence of bronchial asthma in Indian children is estimated to be about 4.75% of the pediatric population.  Most children develop asthma before the age of 8 years, and half of them before 3 years of age. A study in Bengaluru has shown a 3-fold increase in the prevalence of asthma in last 15 years.  In the survey on Delhi school children aged 4-17 years, 11% of asthmatics had been labeled so by their physicians, a positive family history of asthma and presence of smokers in the family emerged as significant risk factors, and no sex related difference in prevalence.  Studies have reported that patients may have markedly abnormal lung functions despite self-reports of freedom from symptoms.  In the study by Pokharel et al., factors associated with the presence of symptoms of asthma were passive smoking, pets at home, and absence of windows in living rooms; whereas family history of asthma, history of worm infestation, fuel used for cooking, location of kitchen, and food allergy did not attain statistical significance.  In the study by Gupta et al., more students with asthma had either parents or other family members smoking at home as compared to nonasthmatics.  In another large cross-sectional study, following findings emerged 15.5% had asthma like symptoms (ALS), 7.8% were labeled, and 82.2% were unlabeled asthmatics, wheezing and shortness of breath were independent diagnostic factors.  Among ALS children, 18.5% showed obstructive flow pattern in the spirometry test (labeled, 24%; unlabeled, 17.4%). In a study measuring peak expiratory flow rate (PEFR) in children with asthma, 65% were mild, 27.5% were moderate, and 7.5% were severe asthmatics.  The increase in PEFR after bronchodilator was directly proportional to the degree of clinical severity of the disease. Still asthma in children is underdiagnosed, and as per a recent report, the prevalence of undiagnosed asthma among children in low income countries is 12-15%. 
The World Health Organization in a joint workshop along with the National Heart, Lung, and Blood Institute, USA, recently reported that asthma still remains underdiagnosed and untreated throughout the world.  This is unfortunate and paradoxical because it is possible today to treat almost all asthmatics so effectively that they are hardly conscious of the disease and are able to lead a normal life at home, work, or the sports field.  A previous study from rural Ludhiana found the prevalence of asthma to be 0.7% only.  The present study was undertaken to measure the prevalence and risk factors for asthma in urban school children in Ludhiana.
| Material and Methods|| |
This cross-sectional study was conducted over a period of 1.5 years. The total children population of urban Ludhiana in the age group of 5 and 15 years is 3,63,086.  An initial study conducted in the rural area of Ludhiana found the prevalence of asthma in as 0.7%.  A fixed sample size of 2500 was taken for urban school children, between 5 and 15 years of age. This sample size was sufficient to detect a minimum prevalence of wheeze or asthma of 2% with a precision of 2% for a confidence level of 95%. The schools were surveyed serially after being arranged in an ascending order (as per the number of students) and the study was terminated when desired sample size was achieved. All of the children on rolls of a particular school in grade 1 and higher were included for the study. In this way, three schools, widely distributed within the municipal limits of urban Ludhiana were selected.
Initially, a questionnaire (questionnaire I, eight items in English language), based on the Indian Academy of Pediatrics (IAP) National Guidelines 2003, was handed over to the children/parents after getting written informed consent. Permission from the school principal was taken before the start of the study. Gurmukhi translation was also provided. The instructions were given regarding filling of questionnaires, and to bring the filled questionnaires after 2-3 days. The deficiencies in the questionnaires were rectified on the day of return after discussion with the children/parents. Any subject whose marks are one or more positive response (s) to the questionnaire I was selected for further evaluation, and was given questionnaire II to assess various risk factors. Age, sex, socioeconomic status (modified Kuppuswamy's socioeconomic status scale), pet at home, family history of allergy and asthma, history regarding wheezing at rest, on exercise and at night, any seasonal variation, family history of smoking, baseline, as well as postexercise challenge PEFR, were all recorded.
General physical and systemic examination was done. Those selected subjects, who were not found to have asthma based on clinical diagnosis, underwent pulmonary function test. PEFR was measured by Mini-Wright peak flow meter in standing position. Best of three measurements was taken. Postexercise PEFR was obtained at baseline and then postexercise (6 min free running test). Bronchial hyperresponsiveness was defined as a drop in PEFR of ≥15% postexercise, and was used for analysis. Prevalence of bronchial asthma among the urban school children was calculated, based on clinical evaluation and results of PEFR test. Institutional ethics committee approval was obtained for the study.
The collected data were tabulated and analyzed by using the statistical package, STATA software (version 9, College station, Texas, USA). Data were entered in customized Epi Info program provided by ISAAC International data center. The prevalence of asthma was calculated for the total population and for specific age groups, by dividing the number of cases found by the size of the population. Odds ratio (OR) with 95% confidence interval (CI) was calculated to assess the univariate association of individual risk factors. Chi-square tests of significance were carried out to test the differences between proportions. To determine the independent effect of various risk factors, multiple logistic regression analysis was performed and adjusted OR with their 95% CI is reported. P < 0.05 was considered as significant.
| Results|| |
The retrieval of questionnaire I was possible in 80% of 2500 distributed. Out of these, 250 responded positively to any of the symptoms suggestive of bronchial asthma or bronchial hyperresponsiveness and were taken up for further testing. Based on the clinical examination and PEFR (baseline and postexercise) testing, 150 were diagnosed as asthma. So, the prevalence of asthma among the urban school children in the present study was calculated as 7.5% (95% CI 5.2-10.5). Again, these 150 cases were provided with questionnaire II, and responses obtained and compared. [Figure 1]shows the overall prevalence of symptoms and severity of asthma in the study population. The most common symptoms reported by the cases were: Wheezing with respiratory infection (cold/flu), nocturnal cough, and exercise-induced wheeze.
|Figure 1: The overall prevalence of symptoms and severity of asthma in the study population|
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The mean age of the children with asthma was 8.67 ± 2.62 years. Agewise distributions of the cases showed asthma to be more prevalent in 5-8 years age group (P = 0.001) compared to 9-12 years or 13-15 years age groups [Table 1]. The family history of asthma and allergy was found to be a risk factor for asthma. The prevalence of asthma was almost 1.5 times (8.8%) among children with a family history of asthma compared to that of those without a family history of asthma (5.9%). This association was found to be statistically significant (P = 0.002) [Table 2]. The M: F ratio was 1.42:1. Males (9.2%) had higher asthma prevalence than the females (5.8%). This difference was not statistically significant (P = 0.78), indicating that increased prevalence of asthma in males was just a chance observation.
|Table 2: Prevalence of asthma as per family history of asthma and allergy|
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Regarding the socioeconomic status, 65% were from upper and 35% from lower socioeconomic status. The prevalence of asthma was lowest in children from middle socioeconomic class (8.6%) and highest among those from high socioeconomic class (14.4%). Among children belonging to a low socioeconomic class, the prevalence was 5.4%. This was not statistically significant. Family history of smoking was present in 10.4% among those with asthma compared to 4.7% without asthma, which was statistically significant (P = 0.012).
On univariate analysis, the factors found to be statistically significant were age groups, family history of asthma, and smoking. Multiple logistic regression analysis showed that in the age group of 5-8 years, a history of asthma in the family and family history of smoking are independently associated with asthma in the study population [Table 3].
|Table 3: Risk factors for current asthma from multiple logistic regression analysis|
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| Discussion|| |
The prevalence of asthma among the urban school children in the present study was calculated as 7.5%. This was in accordance with many previously conducted studies. The prevalence was highest in the age group of 5-8 years. This is in accordance to a study in rural children in Ludhiana district in which the prevalence was highest in the age groups of 5-10 years.  But, we studied wider age groups of 5-15 years, which has not been reported in earlier studies. The M: F ratio for asthma in present study was 1.42:1. The male predominance in the study population was in accordance to a similar study on rural children with chronic/recurrent cough, in which the M: F ratio was 1.4:1.  However, in one study including children of 6-15 years age from the rural population has shown females to be affected more commonly than males (M: F ratio = 0.92:1).  In a survey in Delhi, including school children aged 4-17 years, no sex-related difference in the prevalence of bronchial asthma, was found.  In another study conducted in the city of Bengaluru, prior to puberty the M: F ratio was 3:2, in adolescence this difference got equalized, whereas in adults a female predominance was noted. [13-15]
We also studied socioeconomic status to find out any relationship with the development of asthma. Modified Kuppuswamy index was index for classifying the children into various socioeconomic groups.  Among all the asthma cases, 65% were from upper and 35% from lower socioeconomic status, which was also statistically nonsignificant. In an earlier study, the majority of patients with chronic/recurrent cough belonged to middle socioeconomic class.  In contrary to this, another study found an increased prevalence of asthma in low socioeconomic status.  This could be due to the different socioeconomic scale used in their study and also due to a different selection of the population. As our study was conducted on children in schools of urban Ludhiana, majority of children in school belonged to the higher socioeconomic group. Other studies have found no association between asthma and social class. [18-20]
The family history of bronchial asthma was present in 14.7% cases. Most of the cases had history of asthma in father (9.8%). The prevalence of asthma was almost 1.5 times among children with a family history of asthma compared to that of those without a family history, and is in accordance with previous reports. One study has reported a family history of asthma in 45% of patients with asthma and in 46% of patients with cough variant asthma.  In another study, observed family history of asthma in 42% of asthmatic subjects but in only 10% of nonasthmatics.  In the Delhi survey, the authors reported a strong association between family history of atopic disorders and prevalence of asthma. 
Family history of smoking was present in 10.4% among those with asthma compared to 4.7% without asthma, which was statistically significant. Again, this is in accordance with earlier studies which have shown a strong association of respiratory symptoms with passive smoking. One study noted family history of smoking in 44%,  and another reported it in 23% of cases.  The Delhi survey reported an increased risk for the occurrence of asthma in children having smokers in the family, the risk being 1.6 times more than in children not having smokers in the family. 
The most common symptoms reported by the cases were: Wheezing with respiratory infection (cold/flu) (7.5%), nocturnal cough (6.5%), and exercise-induced wheeze (4.6%). Many epidemiological studies have relied on reported symptoms such as wheeze or episode of dyspnea to identify asthma. [24-27] In the present study, we used the IAP National Guidelines (2003) for the diagnosis of asthma.  Bronchial hyper responsiveness was detected by exercise challenge in our study. Chemical challenges reportedly have more sensitivity but a very low specificity. ,,
A previous study form carried out during the year 1999 in the age group of 1-15 years residing in five villages of Ludhiana found the prevalence of bronchial asthma to be 0.7%.  The primary objective of the study was to study the prevalence of chronic/recurrent cough in children based on a questionnaire. Contrary to this, we primarily studied the prevalence and risk factors of asthma in the urban Ludhiana. This might explain the discrepancy noted in the prevalence. Moreover, present study was conducted almost 8 years after the previous study, which might also show increase in prevalence of asthma as shown in other studies.
Few limitations of the study include the following. Methodologically, 80% responded for screening questionnaire, those did not respond; are likely to be nonasthmatic that probably makes the computed prevalence at a higher side. We could not combine any laboratory test (e.g., skin prick test) to found the proportions of children having underlying atopy.
| Conclusion|| |
The prevalence of asthma in the urban schools of Ludhiana was found to be 7.5%, which was much higher than previously reported. Age groups 5-8 years were commonly affected. Family history of asthma or allergy, and smoking history were found to be significant risk factors for the development of asthma.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]