ABSTRACT
Background and objectives:
Asthma is one among the major health problems found globally with varied prevalence depending upon the geographical location. Several genetic and environmental factors are associated with asthma in children. Our study aims at factors affecting Peak Expiratory Flow Rate (PEFR) in adolescents from Chennai, south India.
Material and Methods:
This observational study was carried out in Chennai schools between July 2019 to Jan 2020 with the sample size of 596 (male 56.4%). Adolescents in the age group of 11 to 14 years were included with Institutional Ethics Committee approval, school permission and consent from the participants. Information about age, gender, history, family history and environmental history was obtained through questionnaire followed by anthropometric measurements. PEFR was measured using Mini Wright peak flow meter. Multiple linear regression analysis was conducted by using SPSS (Statistical Package for the Social Sciences) version 16 with derivation of regression equation for the significant parameters.
Results:
There was a significant correlation of PEFR with age, gender, height, history of nebulization, family history of asthma and environmental smoke (P < 0.05). The other factors like weight, Body Mass Index, chest circumference, physician diagnosed wheeze, history of recurrent respiratory tract infection and pets in the family did not show significant correlation. The correlation coefficient for height was higher than for other anthropometric measurements (r = 0.498).
Conclusions:
Thus, identifying the factors affecting PEFR can provide a basis for targeted prevention efforts in children and adolescents. Prediction formula derived from statistical analysis can be used in diagnosing and following adolescents with asthma from south India.
Keywords: Adolescents, asthma, family history, height, nebulization, PEFR, smoke
Introduction
Asthma is one among the major health problems found globally. The bronchial asthma prevalence in Indian children ranges from 5% to 23% depending upon the geographical location.[1,2] It is found that several genetic and environmental factors are associated with asthma in children. From various studies in the past we know that anthropometric parameters affect the pulmonary function tests in children.[3,4] Our study was conducted in adolescents from Chennai south India focusing on the effects of anthropometry, genetic and environmental factors on the lung function as assessed by the PEFR.
The functional status of the lungs can be measured by Peak Expiratory flow rate (PEFR). This pulmonary function test is a simple and reliable way of assessing the airway obstruction, especially in asthma. It is useful in monitoring the asthma severity and assessing the response to treatment. PEFR values are like the other methods of assessing pulmonary function tests.[5] The symptom score, the FEV1 (Forced Expiratory Volume in one second), FVC (Forced Vital Capacity) and PEFR are all good indicators of response to treatment in asthma.[6]
The mini-Wright peak flow meter is an easy and economical instrument useful for home monitoring in asthmatic children. The baseline PEFR is recorded during asymptomatic period. Then the PEFR is monitored daily to find its variations, which serves as a guide in assessing the asthma severity, treatment response and the need for any additional treatment.
Early recognition of severity of asthma is essential to prevent mortality and it can be conducted by measuring the PEFR. The measured PEFR values from the children will be compared with the normal PEFR values using nomogram or prediction equations, which are derived from large number of children. It has been shown that there are racial and ethnic differences in pulmonary function especially lung volumes. Our study helps in assessing the PEFR and the factors affecting it in south Indian adolescents.
Material and Methods
This is an observational study carried out in the region of Poonamalle, Chennai with the sample size of 596. Adolescents in the age group of 11 to 14 years from various schools in Chennai were included in the study. The prior permission from our Institutional Ethics Committee was obtained. The study was initiated with school authority approval and consent from their parents. Assent was obtained from the adolescents before including them in the study. Study period was from July 2019 to Jan 2020.
Adolescents with history of cardiopulmonary disease, chest wall and spine deformity were excluded from the study. A questionnaire consisting of history and relevant family history, age and gender was administered among the adolescents, who were willing to participate in this study, and it was filled by the parents. The questionnaire had the following components. They were, history of nebulization (Q1), physician diagnosed wheeze (Q2), recurrent respiratory tract infection (more than 3 year) (Q3), history of hospitalization for a respiratory illness (cough/breathlessness) (Q4), family history of asthma (Q5), exposure to smoke/indoor pollution (passive smoking/burning of firewood) (Q6) and history of pets in the family (dog/cat) (Q7) in the past 2 years.
After obtaining the information, the anthropometric measurements were taken as per standard guidelines. Weight in kg was measured using an electronic weighing scale (Omron Hn-286) with minimal clothing without shoes and height measured by stadiometer. Chest circumference was measured during deep inspiration below the level of nipple using a non-stretchable measuring tape. A trained female nurse helped in this chest circumference measurement for female adolescents. BMI (Body Mass Index) was calculated using the formula Wt. in kg divided by Ht in mt2 and it was interpreted using revised IAP growth chart 2015.
The PEFR was measured using the Mini-Wright peak flow meter (Clement Clarke). It has a mouthpiece and a cylindrical shape body and a spring–piston within the body of the instrument that can slide freely when the adolescent blows through the mouthpiece. The piston is moved to the front with each blow. The scale is graduated from 60 L/min to 800 L/min. The maximum displacement of the piston is recorded by the indicator in the body of the instrument. The indicator was brought back to the position of zero by the person, who operates it. The instrument is held horizontally during usage and the mouthpiece is detachable.
The procedure was first demonstrated to the participants in groups consisting of 10 members in each group. The pointer was first moved to the bottom of the scale. The instrument was held horizontally with fingers without covering the slot in upright standing position. After taking deep breath slowly through mouth, the mouthpiece was placed with the lips closed around it tightly. The hole of the mouthpiece was not blocked by tongue. Blowing through the mouthpiece was done as fast and hard as possible. After noting down the reading from the instrument, the pointer was moved to the bottom of the scale again for the next blow.
Each participant had two trials first followed by three blows through the instrument. The best reading out of the three blows was considered as the PEFR of the subject. If a large difference between the measured three readings of the participant was found, procedure was taught again avoiding faulty procedure. Disposable mouthpiece was used for each participant during the procedure.
Statistical analysis of the collected data was done using SPSS version 16. The statistical methods used were Student t-test, Pearson’s correlation coefficient and multiple linear regression analysis.
Results
The total study sample was 596 (boys: 56.4%) in the age group of 11 to 14 years. The mean age of the study sample was 12.22 with 1.02 SD. The independent variables (age, weight, BMI, height, and chest circumference) showed equal distribution of mean values in both boys and girls. Table 1 with increase in mean height as age advances. As per the revised IAP growth chart 2015 we classified the adolescents as normal (60.4%), obese/overweight (36.5%) and underweight (3%). The diagnosis of asthma in children is based on history, clinical findings, and investigations like pulmonary function tests. In our study family history of asthma, history of nebulization and physician diagnosed wheeze was present in 14.6%, 24.8%, and 13.4% of participants, respectively.
Table 1.
Demographic profile with mean values of anthropometric measurements
| S. no | Anthropometry | Total=596 | Boys=336 (56.4%) | Girls=260 (43.6%) | |||
|---|---|---|---|---|---|---|---|
|
|
|
|
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| Mean | SD | Mean | SD | Mean | SD | ||
| 1 | Age in years | 12.22 | ±1.02 | 12.18 | ±1.2 | 12.27 | ±1.01 |
| 2 | Weight in kg | 42.71 | ±11.22 | 42.53 | ±11.4 | 42.95 | ±11.01 |
| 3 | Height in m2 | 1.49 | ±0.08 | 1.49 | ±0.09 | 1.48 | ±0.08 |
| 4 | Chest circumference in cm | 75.55 | ±8.66 | 75.85 | ±8.86 | 75.18 | ±8.39 |
| 5 | BMI | 19.10 | ±3.92 | 18.90 | ±3.81 | 19.36 | ±4.05 |
|
| |||||||
| Age in years | n % | Mean weight in kg | Mean Ht in m2 | Mean CC in cms | |||
|
|
|
|
|||||
| Boys | Girls | Boys | Girls | Boys | Girls | ||
|
| |||||||
| 11 | 179 (30) | 38.89 | 38.67 | 1.43 | 1.44 | 73.09 | 71.48 |
| 12 | 189 (31.7) | 40.73 | 41.12 | 1.48 | 1.47 | 75.49 | 75.28 |
| 13 | 148 (24.8) | 45.55 | 44.98 | 1.53 | 1.51 | 77.68 | 76.08 |
| 14 | 80 (13.4) | 50.35 | 51.83 | 1.60 | 1.56 | 80.09 | 80.67 |
CC=Chest circumference, Ht=Height, SD=Standard deviation
The mean PEFR value increases significantly with age (P < 0.05). Also, there is a significant difference in PEFR values between boys and girls by independent t test (P 0.003), boys having more PEFR values than girls. The subgroup analysis in each age group showed similar difference among boys and girls between 12 to 14 years and it was significant. The difference was not significant in 11 years age group [Table 2].
Table 2.
Mean PEFR with age and gender
| n=596 (%) | Mean PEFR L/mt | SD | P | |
|---|---|---|---|---|
| Age | ||||
| 11 years | 179 (30) | 238.05 | ±46.862 | <0.05 |
| 12 years | 189 (31.7) | 256.17 | ±49.020 | |
| 13 years | 148 (24.8) | 289.99 | ±53.894 | |
| 14 years | 80 (13.4) | 290.84 | ±53.918 | |
| Gender | ||||
| Male | 336 (56.4) | 269.68 | ±58.131 | 0.003 |
| Female | 260 (43.6) | 256.15 | ±49.322 | |
| Total | 100% | 263.78 | ±54.833 | |
| Subgroup | ||||
| 11 years male | 106 (31.6) | 240.01 | ±48.313 | 0.502 |
| 11 years female | 73 (28.1) | 235.21 | ±44.841 | |
| 12 years male | 108 (32.1) | 263.07 | ±52.497 | 0.025 |
| 12 years female | 81 (31.2) | 246.98 | ±42.556 | |
| 13 years male | 78 (23.2) | 300.77 | ±56.033 | 0.010 |
| 13 years female | 70 (26.9) | 277.97 | ±49.054 | |
| 14 years male | 44 (13.1) | 302.27 | ±55.021 | 0.035 |
| 14 years female | 36 (13.8) | 276.86 | ±49.774 |
PEFR=Peak expiratory Flow Rate
High linear positive correlation with PEFR was found for height followed by age and gender in our study. The coefficient of correlation was 0.498 between height and PEFR in both boys and girls, which is higher than the values in other parameters like age (r = 0.385), weight (r = 0.318) and chest circumference (r = 0.267).
The regression analysis of the various parameters including the questionnaires showed significance for age, gender, height, history of nebulization (Q1), family history of asthma (Q5) and exposure to smoke/indoor pollution (Q6). [Table 3] The other factors like weight, BMI, chest circumference, physician diagnosed wheeze, history of recurrent respiratory tract infection and pets in the family did not show any significant correlation. We derived the regression equation for the significant parameters.
Table 3.
Multiple linear regression analysis of PEFR with the variables
| Variables | t | Beta standardized coefficient | P |
|---|---|---|---|
| Age | 4.231 | 0.176 | 0.000 |
| Gender | 3.985 | 0.133 | 0.000 |
| Weight | −1.012 | −0.011 | 0.191 |
| Height | 9.732 | 0.365 | 0.000 |
| Chest circumference | 1.353 | 0.074 | 0.696 |
| BMI | −1.830 | −0.106 | 0.250 |
| History of nebulization (Q1) | −6.059 | −0.207 | 0.000 |
| Physician diagnosed wheeze (Q2) | −0.031 | 0.008 | 0.975 |
| Recurrent respiratory tract infection (Q3) | −0.402 | −0.011 | 0.688 |
| Hospitalization for a respiratory illness (Q4) | −0.761 | −0.025 | 0.447 |
| Family history of asthma (Q5) | −3.371 | −0.117 | 0.001 |
| Exposure to smoke/indoor pollution (Q6) | −2.648 | −0.083 | 0.008 |
| History of pets in the family (Q7) | −0.834 | −0.027 | 0.408 |
Regression equation
PEFR= −215 + 9.2(age) +14.681(gender)* +2.498(Ht) −26.874 (Q1)** −18.469(Q5)** −18.618 (Q6)**
*male = 1, female = 0
**yes = 1, no = 0
Discussion
In our study we had a significant linear correlation of PEFR with age, gender and height with height having the highest correlation. The PEFR increases progressively with age. The various studies done in South Indian children showed significant positive correlation with height as seen in our study.[7,8] The Nigerian study has shown similar findings with positive correlation of PEFR with age and height and the PEFR was higher in boys than girls.[9] The studies done in north India showed similar findings.[10]
The subgroup analysis performed in our study showed significant difference in PEFR between adolescent boys and girls in the age group of 12 to 14 years. In a study done in healthy Nepalese children, adolescent males had higher PEFR values compared to females.[11] It is noted that before puberty, PEFR is almost same in both boys and girls but after puberty the value is found to be higher in boys than girls due to the difference in muscle mass.
The study done by Schwartz et al.[12] in children to know the respiratory effect of tobacco smoke showed decline in PEFR in children exposed to tobacco smoke. Our study has shown the effect of environmental pollution on the pulmonary function with significant decrease in PEFR. In a study done in north India, a strong association was found between the poor lung function and outdoor air pollutants.[13] The significant effect of firewood and passive smoking on peak expiratory flow rate correlates well with other studies.[14,15,16]
The association between family history of asthma and decrease in PEFR was found significant in our study. In their study, Mehta et al. and Burke et al.[17,18] found that family history of asthma was significantly associated with lower PEFR. Asthma runs in families not only due to the same genetic makeup but also the same environmental factors, playing an important role in asthma etiology.
In one study less allergic manifestations in the form of asthma, allergic rhinitis or eczema was seen in children exposed to dogs and cats in the first year of life.[19] In another study, allergy to laboratory animal allergens was found in Poland.[20] Our study did not show any significant correlation of PEFR with pet animals in the family.
The correlation of PEFR with age, gender, height, history of nebulization, environmental smoke exposure and family history of asthma is significant in our study. These factors need to considered, while assessing the PEFR in children and adolescents. Thus, identifying the factors affecting PEFR can provide a basis for targeted prevention efforts in adolescents. Prediction formulas derived from statistical analysis can be used in diagnosing and following adolescents with asthma from south India.
Author’s contributions
GK: Data collection, data analysis, study design, literature search, and manuscript writing. SP: Study design, literature search, manuscript writing, critical revision and interpretation. GT: Data analysis, critical revision and interpretation. All authors approved the final draft.
Ethical clearance
a. Status – obtained
a. Name of the Ethics Committee – Institutional Ethics Committee, Sri Ramachandra Institute of Higher Education and Research
b. Date and number –30/12/2017 CSP-MED/17/SEP/38/116
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
References
- 1.Pal R, Dahal S, Pal S. Prevalence of bronchial asthma in Indian children. Indian J Community Medicine. 2009;34:310–6. doi: 10.4103/0970-0218.58389. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Jain A, Vinod Bhat H, Acharya D. Prevalence of bronchial asthma in rural Indian children: A cross-sectional study from South India. Indian J Pediatrics. 2010;77:31–5. doi: 10.1007/s12098-009-0308-6. [DOI] [PubMed] [Google Scholar]
- 3.Raju PS, Prasad KV, Ramana YV, Murthy KJ. Pulmonary function tests in Indian girls--prediction equations. Indian J Pediatr. 2004;71:893–7. doi: 10.1007/BF02830828. [DOI] [PubMed] [Google Scholar]
- 4.Agaba PA, Thacher TD, Angyo IA, Agaba EI. Peak expiratory flow rates in healthy Nigerian children. J Trop Pediatr. 2003;49:157–9. doi: 10.1093/tropej/49.3.157. [DOI] [PubMed] [Google Scholar]
- 5.Bongers T, O’Driscoll BR. Effects of equipment and technique on peak flow measurements. BMC Pulm Med. 2006;6:14. doi: 10.1186/1471-2466-6-14. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Anandi S, Tullu MS, Lahiri K. Evaluation of symptoms and spirometry in children treated for asthma. Indian J Med Res. 2016;144:124–7. doi: 10.4103/0971-5916.193299. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Pulickal AS, Fernandez GV. Peak expiratory flow rate in healthy rural south Indian school children predicted from body height. Indian J Public Health. 2007;51:117–9. [PubMed] [Google Scholar]
- 8.Swaminathan S, Venkatesan P, Mukunthan R. Peak expiratory flow rate in south Indian children. Indian Pediatr. 1993;30:207–11. [PubMed] [Google Scholar]
- 9.Mojiminiyi FB, Igbokwe UV, Ajagbonna OP, Jaja SI, Ettarh RR, Okolo RU, et al. Peak expiratory flow rate in normal Hausa-Fulani children and adolescents of northern Nigeria. Ann African Med. 2006;5:10–5. [Google Scholar]
- 10.Taksande A, Jain M, Vilhekar K, Chaturvedi P. Peak expiratory flow rate of rural school children from Wardha district, Maharashtra in India. World J Pediatr. 2008;4:211–4. doi: 10.1007/s12519-008-0039-1. [DOI] [PubMed] [Google Scholar]
- 11.Dhungel KU, Parthasarathy D, Dipali S. Peak expiratory flow rate of Nepalese children and young adults. Kathmandu Univ Med J (KUMJ) 2008;6:346–54. doi: 10.3126/kumj.v6i3.1710. [DOI] [PubMed] [Google Scholar]
- 12.Schwartz J, Timonen KL, Pekkanen J. Respiratory effects of environmental tobacco smoke in a panel study of asthmatic and symptomatic children. Am J Respir Crit Care Med. 2000;161:802–6. doi: 10.1164/ajrccm.161.3.9901002. [DOI] [PubMed] [Google Scholar]
- 13.Chhabra SK, Chhabra P, Rajpal S, Gupta RK. Ambient air pollution and chronic respiratory morbidity in Delhi. Arch Environ Health. 2001;56:58–64. doi: 10.1080/00039890109604055. [DOI] [PubMed] [Google Scholar]
- 14.Li YF, Gilliland FD, Berhane K, MecConnell R, Gauderman WJ, Rappaport EB. Effects of in utero and environmental tobacco smoke exposure on lung function in boys and girls with and without asthma. Am J Respir Crit Care Med. 2000;162:2097–104. doi: 10.1164/ajrccm.162.6.2004178. [DOI] [PubMed] [Google Scholar]
- 15.Tsai CH, Huang JH, Hwang BF, Lee YL. Household environmental tobacco smoke and risks of asthma, wheeze and bronchitic symptoms among children in Taiwan. Respir Res. 2010;11:11. doi: 10.1186/1465-9921-11-11. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Lankarani NB, Kreis I, Griffiths DA. Air pollution effects on peak expiratory flow rate in children. Iran J Asthma Immunol. 2010;9:117–26. [PubMed] [Google Scholar]
- 17.Mehta B, Garg K, Ambwani S, Bhandari B, Bhagat OL. Peak expiratory flow rate: A useful tool for early detection of airway obstruction in school children. Open Med J. 2016;3:159–65. [Google Scholar]
- 18.Burke W, Fesinmeyer M, Reed K, Hampson L, Carlsten C. Family history as a predictor of asthma risk. Am J Prev Med. 2003;24:160–9. doi: 10.1016/s0749-3797(02)00589-5. [DOI] [PubMed] [Google Scholar]
- 19.Hesselmar B, Hicke-Roberts A, Lundell A, Adlerberth I, Rudin A, Saalman R, et al. Pet-keeping in early life reduces the risk of allergy in a dose-dependent fashion. PLOS ONE. 2018;13:e0208472. doi: 10.1371/journal.pone.0208472. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Krakowiak A, Wiszniewska M, Krawczyk P, Szulc B, Wittczak T, Walusiak J, et al. Risk factors associated with airway allergic diseases from exposure to laboratory animal allergens among veterinarians. Int Arch Occup Environ Health. 2007;80:465–75. doi: 10.1007/s00420-006-0153-0. [DOI] [PubMed] [Google Scholar]