Indian Pediatrics 2002; 39: 23-29
Chronic/Recurrent Cough in Rural Children in Ludhiana, Punjab
CHRONIC cough is a common problem encountered by pediatricians and other practitioners dealing with children. Though most coughs are self limiting; chronic/recurrent cough is unlikely to occur in the absence of disease or abnormal physiological functioning(1). Chronic cough has been variously defined in literature but is commonly referred to as a persistence of cough for more than three weeks (2-6).
It must be recognized that children presenting with chronic/recurrent cough may have a wide variety of underlying disorders ranging from minor conditions to life threatening ones. Therefore, a systematic diagnostic approach is needed to determine the most likely underlying pathogenic mechanism; selecting the simplest effective therapy for the underlying process, which may often be only symptomatic therapy, and carefully evaluating the effect of therapy(7).
There are a number of factors responsible for prevalence and age distribution of chronic/recurrent cough. It may vary from place to place since factors may be peculiar to the setup. There is a paucity of data on population based studies on chronic/recurrent cough in Indian children. This prospective study on rural children of Ludhiana was conducted to determine the prevalence, age distribution and common causes of chronic/recurrent cough in children aged between 1-15 years.
Subjects and Methods
This study was carried out during the year 1999 on the pediatric population in the age group of 1-15 years residing in five villages of Dehlon block of Ludhiana which is covered under field area of Rural Health Center Pohir, a branch of Dayanand Medical College and Hospital Ludhiana. These villages are situated about 25 km from the industrial town of Ludhiana. The main source of income in these villages is related to agricultural practices with both men and women being actively involved in the fields. The majority of the population are Sikhs (89%).
Out of 1682 families belonging to the study area, 40 had migrated to cities for work. From the 1642 resident families, all infants were excluded leaving a total number of 2275 children for screening carried by house to house survey to identify children in the age group of 1-15 years with chronic/recurrent cough which formed the study group. Chronic cough was defined as cough lasting for more than three weeks. Recurrent cough was defined as cough lasting for more than 10 days duration with 4 or more episodes in a year(2-6).
The clinical and epidemiological informa-tion from the children in the study group was obtained using a questionnaire which included prevalidated criteria for diagnosis of bronchial asthma (modified American Thoracic Society Criteria)(8,9) and Post Nasal Drip Syndrome (PNDS)(10,11). Special emphasis was laid on allergic symp-toms (skin lesions, conjunctivitis, rhinitis, etc.), occupation and absenteeism from school/work. Prescription slips and other documents carried by parents were thoroughly screened for details of previous investigations done, treatment received and any hospital admission. Family history of atopy, tuberculosis, smoking and asthma in any family member was recorded. The socio-economic status of the family was judged by the Modified Udai Pareek Scale (MUP) for rural area(12). MUP score covered caste, occupation and education of family head, mother’s education, family type (joint/nuclear), family size, house ownership, type of house (pucca, kutcha, mixed), number of rooms, drinking water facility. The socio-economic status was graded according to the MUP score as: (i) £15 – low; (ii) 16-28 – middle; and (iii) >28 – high. Variables like number of pets in the house, overcrowding and cooking fuel used were noted. Overcrowding was expressed by number of persons per room. The following standards were utilized for defining overcrowding, taking adults and children above 10 years as one person unit and children between 1-10 years as half person unit(13): 1 room = 2 person units; 2 rooms = 3 person units; 3 rooms = 5 person units; 4 rooms = 7½ person units; 5 or more rooms = 10 person units (additional 2 for each further room).
A detailed examination was carried out on all the cases with chronic/recurrent cough as identified by the stated definition. Records were made of weight, nutritional status, respiratory rate, clubbing, cyanosis, postnasal drip, other physical signs and systemic examination especially respiratory system. This was followed by various investigations which included complete blood count, Mantoux test, chest X-ray in all children and stool microscopy and X-ray para nasal sinus (PNS) in children with symptoms suggestive of allergy and sinusitis, respectively. Peak Expiratory Flow Rate (PEFR) measurement with Standard Mini Wright peak flow meter was done in children above 5 years of age with chronic/recurrent cough. Cases were followed till underlying etiology was established by clinical and laboratory parameters.
Asthma was diagnosed based on clinical symptomatology using modified American Thoracic Society (ATS) criteria. Presence of at least three of the following symptoms in the past twelve months was taken as bronchial asthma: (a) persistent cough, (b) wheeze with cold, (c) wheeze apart from colds and (d) dyspnea with wheeze(8,9). PNDS was considered when (i) patients described the sensation of having something drip down into their throats, frequent nasal discharge, and/or the need to frequently clear their throats, or (ii) physical examination of the nasopharynx or the oropharynx revealed mucoid or mucopurulent secretions and/or a cobblestone appearance of the mucosa(10,11,14).
Facilities for endoscopy, 24 hour pH monitoring, immunoglobulin levels, sweat chloride test, bronchoprovocation tests, special microbiological tests, bronchoscopy and CT chest were not available.
Five hundred children in the study population were chosen as control group by fixed random distribution. Variables asso-ciated with chronic/recurrent cough were noted in the control group for comparison with the positive cases.
Data was analyzed statistically using Z test and chi square test. Potential risk factors for chronic/recurrent cough were tested as predictors of symptom occurrence in a multiple logistic regression analysis.
A total of 2275 children between 1-15 years were screened for chronic/recurrent cough. There were 1253 boys and 1022 girls with male-female ratio of 1.2:1. Twenty four out of 2275 children were diagnosed with chronic/recurrent cough thereby showing the prevalence rate of 1.06%. The maximum number of cases in the present study were seen in the age group of 5 to 10 years with mean age of 7.8 ± 3.1 years. Out of 24 children, there were 14 males (58.3%) and 10 females (41.7%). Seventeen (70.8%) patients with chronic/recurrent cough had onset £5 year as compared to 7 (29.2%) children with onset of cough after the age of 5 years (p <0.01). Mean age of onset was 7.29 ± 5.61 years.
The most common cause was bronchial asthma diagnosed in 16 patients (66.7%) followed by PNDS seen in 6 cases (25%). Postnasal drip syndrome included five patients with allergic rhinitis and one child with chronic sinusitis. Upper respiratory tract infection (URI) contributed the third cause of recurrent cough and was observed in two cases amounting to 8.3% of the total subjects (Table I).
Family history of allergy/asthma was noted in 11 (45.8%) children with chronic/recurrent cough as compared to 52 (10.4%) in the control group. Out of 16 patients diag-nosed with asthma, family history of asthma was observed in 7 children (43.8%). These differences were statistically significant (p <0.01). Family history of smoking was recorded in 16.7% of cases as compared to 6.4% in the control cases (Table II). The result was statistically significant (p = 0.05).
Table II__Association with Family History of Allergy/Asthma, Smoking and Environmental Factors
Peak expiratory flow rate (PEFR) recording was done on 18 children ( >5 years) with chronic/recurrent cough out of which 14 (77.8%) demonstrated changes suggestive of airway obstruction (PEFR less than 80% of predicted value as per percentile charts of normal PEFR values for boys and girls according to age)(15-17). PEFR <60% was observed in one child, 60-70% in ten cases and 70-80% in three patients, respectively. Stool microscopy was performed on eight cases with allergic symptoms and results were normal in all the patients.
Overcrowding was noted in 58.3% of the cases as compared to 44.8% in the control group (p>0.10). Pets were found in 3 houses (12.5%) among cases in contrast to 9% in control group (p>0.10). Smoke producing fuels (wood, cowdung, kerosene, etc.) were used as cooking medium by 17 (70.8%) families among children with chronic/recurrent cough in comparison to 310 (62%) in the control group (p >0.10) (Table II).
School absenteeism was observed in 70% patients with chronic/recurrent cough. Mean loss of school days over one year was 17.5 ± 9.37 days. Out of 15 (62.5%) patients who had earlier received treatment for chronic/recurrent cough, only 9 (37.5%) were seen by a qualified doctor. No child had been hospitalized for cough.
Using multiple logistic regression analysis, age of onset £5 years (p <0.01), family history of allergy/asthma (p <0.05) and family history of smoking (p <0.01) were found to be associated with an increased risk of chronic/recurrent cough in children (Table III).
Earlier studies on chronic cough in children have reported prevalence between 4.8 – 6.8% in community based surveys in the West(18-20) and 8 to 31.8% in hospital based studies(5,21). The wide difference in prevalence rates may be due to variations in methodology, distribution of risk factors and population surveyed. In the present study of 2275 rural children aged 1 to 15 years belonging to five villages in Ludhiana, district of Punjab, the prevalence of chronic/recurrent cough was 1.06%. The low prevalence in our study could be due to low levels of air pollution in vicinity of study area, low percentage of family history of smoking (majority of population being Sikhs) and relatively better socio-economic status of Punjabis as compared to other areas.
In the previous studies, asthma is mentioned as the most common cause of chronic cough(1,5,21,22). Fifteen children with chronic cough have been described earlier(23), who exhibited changes in pulmo-nary function testing on exercise similar to changes noted in children with mild exercise induced bronchospasm. All subjects responded significantly to theophylline therapy. This study concluded that chronic cough in some children may be a manifestation of air way hyper reactivity(23) Other studies had documented similar findings(24,25). Holinger et al. in their study of 72 patients with chronic cough documented cough variant asthma to be the most common cause(1). Bernztein et al. also found cough variant asthma in 52% cases(22). Other workers have also identified asthma as the most common underlying etiology, occurring in 59% and 85% of their patients, respect-ively(5,21). In the present study, 66.7% of patients with chronic/recurrent cough were having asthma as the underlying etiology.
Although, studies (1,22,26,27) on chronic cough have shown cough variant asthma as the most common type of asthma, we had no case in the present study. All sixteen patients reported episodic or chronic dyspnea and/or wheezing besides cough suggesting that cough predominant asthma is more common.
Holinger et al. (23%)(1), Bernztein et al. (6%)(22), Callahan et al. (13.7%)(5) and Paramesh et al.(7.6%)(21) have reported post nasal drip syndrome as the second commonest cause of persistent cough. The present study also shows post nasal drip syndrome (25%) as the second commonest cause. There are a variety of causes for the postnasal drip syndrome which include allergic, perennial non-allergic, postinfectious, vasomotor rhinitis, sinusitis and environmental irritants (10,11,14,28). Our patients with PNDS included five children with allergic rhinitis and one with chronic sinusitis.
In our study of chronic/recurrent cough, family history of allergy/asthma was noted in 45.8% as compared to 10.4% in the control group (p <0.01). A significant association between history of asthma or hay fever in either parent and chronic cough was also noted earlier(19,20,26).
A family history of smoking was observed in 16.7% of the children with chronic/recurrent cough and 6.4% of the control group. This is in contrast to the earlier(19) finding where family history of smoking was noted in 44% of children with persistent nocturnal cough and 56% of children in asymptomatic group. The lower percentage of family history of smoking in our study is attributable to religious practices in the region with majority of Sikhs being nonsmokers. The association between family history of smoking and chronic/recurrent cough was found to be significant (p = 0.05). This is in concordance with earlier observations where a significant association was documented between household smokers and persistent cough(29). However, other workers found no significant association between parental cigarette smoking and chronic cough(18,20).
Majority of children with chronic/recurrent cough (83.3%) in our study belonged to middle socio-economic class (according to MUP score for rural popula-tion). This distribution was in conformity with that in the control population.
Contributors: DS was the project coordinator and chief investigator. He is responsible for the study design, analysis and interpretation of the data. He will act as the guarantor for the article. VA was responsible for conducting physical examination and identification/categorization of cases and participated in data collection, recording and data analysis. PS conducted the literature search, guided the preparation of the manuscript and was also responsible for the critical review of the manuscript.
Competing interests: None stated.