Peak Expiratory Flow Rate amongst an Aboriginal Community in Peninsular Malaysia

Hui Jean Yap , Wooi Wooi Khaw , Patmapriya Ramasamy , Siti Nurayu Muhammad Idris , Baitil Aizah Mohd Sibi , Daniel Ngu Leong Hoe , Loh Li-Cher , Abdul Rashid Khan B. Md Jagar Din

Hui Jean Yap1*, Wooi Wooi Khaw1, Patmapriya Ramasamy1, Siti Nurayu Muhammad Idris1, Baitil Ai?zah Mohd Sibi1, Daniel Ngu Leong Hoe1, Loh Li-Cher2, Abdul Rashid Khan B. Md Jagar Din3
  1. Department of Public Health Penang Medical College, Penang, Malaysia
  2. Prof.; Department of Medicine, Penang Medical College, Penang, Malaysia
  3. Assoc Prof.; Department of Public Health, Penang Medical College, Penang, Malaysia
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Abstract

Background: The ‘Orang Asli’ or the aboriginal people of peninsular Malaysia have high morbidity, mortality and poverty rates and they lag very far behind in basic infrastructure, literacy and education. Information on peak expiratory flow rate (PEFR) among Orang Asli is extremely limited and there has only been one such study which was carried out in 1971.

Aims & Objectives: To determine the lung function of a community of Orang Asli in Peninsular Malaysia and to determine their association with various socio-demographic and anthropometric factors with their lung function. Methods: PEFR was measured using the Wright Peak Flow meter and the best of the three readings taken was used. A total of 119 respondents participated in the study.

Results: A total of 79 respondents (66.9%) reached 80% of their predicted PEFR value while 39 (33.1%) fell below 80% of their predicted PEFR value. Results showed a significant association in PEFR between genders (p=<0.001), height (p=0.004), exposure to noxious particles (p=0.023) and level of education (p=0.014). Linear regression showed that the PEFR increased with increasing height (p=0.004) and was higher in men (p=<0.001), those not exposed to noxious particles (p=0.023) and those with a higher education level (p=0.014). Conclusion: Orang Asli who are tall, male, with higher levels of education and not exposed to noxious particles have better lung function.

Keywords

Peak expiratory flow rate (PEFR), Orang Asli, Malaysia

Introduction

Orang Asli is the Malay term literally meaning ‘original people’. This is the term used for the indigenous minority people living in peninsular Malaysia. The Orang Asli in Peninsular Malaysia comprises of three main ethnic groups namely Negrito, Senoi and Proto Malay. Each ethnic group is further divided into multiple sub-ethnicities. The sub ethnic groups of the Negrito group include Kensiu, Kintak, Lanoh, Jahai, Mendriq and Bateq. The Senoi include Temiar, Semai, Semoq Beri, Che Wong, Jah Hut and Mah Beri and the sub ethnic groups of the Proto Malay include Temuan, Semelai, Orang Kanaq, Orang Kuala and Orang Seletar. According to 2008 data, they numbered about 141,230. It is reported that 36.9% aborigines live in rural areas, 62.4% in marginal areas and 0.7% in city areas.1 The morbidity and mortality rates among the Orang Asli are high.2 The Orang Asli have three times the incidence of tuberculosis as the national average.3 The poverty rate for Orang Asli has been reported as higher than the mainstream Malaysian population4 and they lag very far behind in basic infrastructure, literacy and education.5 The Orang Asli used to survive by hunting and foraging food in the jungle1, but recently due to the encroachment by developers and loggers into their land some ethnic groups of Orang Asli are living closer to the cities and townships. This forced urbanization has led to the changes in types of employment and lifestyle which has led to changes in their daily activities leading to a sedentary lifestyle. New occupations which expose them to noxious substances may have an impact in their lung capacity.
Peak Expiratory Flow Rate (PEFR) value can be used as an indicator of a person’s health and it is a clinical tool in diagnosis, management and follow up for respiratory diseases. It has been shown that as a person ages, their PEFR decreases.6 Peak flow measurements can be used to measure the strength of muscles of respiration6 and thus can be used to monitor respiratory impairment. Diurnal variation of PEFR is used to diagnose and in the management of bronchial asthma.6 Self-monitoring of PEFR by asthmatic patients also helps to increase the effectiveness of treatment.7 Limited research has been carried out and published in the area of measuring lung function using peak flow meter in Malaysia let alone among the Orang Asli. The studies that were carried out in Malaysia were mainly focused on the elderly or children.8,9,10 Only one reported study was carried out among the Orang Asli to determine their lung function in 1971 by Dugdale et al.11 They found most of the respondents peak expiratory flow rate (PEFR) value was lower than the predictive value. However, the ethnicity of the Orang Asli population in that study was not specified. Furthermore, because of the differences in culture and practices and the magnitude of health problems among these communities than that of mainstream Malaysians it is important to evaluate whether the socio-demographic, economic and anthropometric indices would affect the Orang Asli’s respiratory function. An overview of their general lung functions and factors contributing to the impairment of lung function can be recognised and can be used as a reference for future studies and as a comparison to the general population. Thus, this study was conducted to evaluate the lung function among the Semai Orang Asli living in Cameron Highlands, Malaysia by determining the Peak Expiratory Flow Rate (PEFR) using a Peak Flow Meter.

Methods

Setting

This study was conducted among the Semai people who are the sub-ethnic of the Senoi Orang Asli living in Cameron Highlands, Malaysia. The village is located on a hilly land with the houses spreading across the hill and is approximately one km to the nearest town. Most of the villagers here are employed as elementary workers such as hotel cleaners, garbage collectors and laborers.

Study design

A cross sectional study was conducted in April 2012.

Sampling

There were approximately 1300 Semai Orang Asli living in this village.12 A convenience sampling method was used to sample the study population from a total of 63 households. All healthy subjects who were 20 years and above, who consented and were able to communicate effectively were eligible to participate in the study. Excluding criteria included those who were bedridden, because participants were required to sit upright to perform the assessment. Other exclusion criteria’s included those who were diagnosed with pulmonary tuberculosis (PTB) and were on medication at the time of the study. This was done as a preventative measure to avoid potential spread of PTB. Respondents with severe wheezing, shortness of breath, severe oral deformities and oral diseases were also excluded as they would not have been able to perform the test due to their condition. Respondents who failed on three consecutive attempts due to incorrect technique despite adequate instructions were also excluded from the study to avoid causing annoyance to them. Respondents suffering from acute or chronic cough with or without productive sputum were included; however it was ensured that they cleared their sputum before blowing into the peak flow meter. Respondents with dental deformity or wearing dentures were also included as only the lips are required to completely seal the mouthpiece. Respondents who were diagnosed with pulmonary tuberculosis but have been successfully treated were also included.

Tools

A questionnaire was designed for this study. The interviews were conducted in the participant’s homes. Data was collected by trained medical students. The students were trained in the classroom and were taught the correct method of using the peak flow meter. Besides the baseline socio-demographic information, peak expiratory flow rate was measured using the Wright peak flow meter which is a rapid and reliable measure of ventilator function.13 The instrument is inexpensive, portable and easy to operate and is practical for both hospital and general practice and as a screening tool in epidemiological studies.13 The Wright Peak Flow meter was used with the respondent in an upright sitting position. By holding the peak flow meter with the finger’s grip of the right hand away from their mouth, respondents were told to inhale as deeply as possible followed by sealing the disposable mouthpiece tightly with their lips. Respondents were given instruction to exhale as quickly and completely as possible. Three satisfactory readings were taken from the peak flow and the highest measurement of the three was taken as the maximum peak flow value for the study.14 Besides the PEFR, Slim guide skinfold caliper was used to measure the thickness skin fold and its subcutaneous fat from four areas – biceps, triceps, subscapular and suprailiac. Body density was then calculated using the skinfold measurements using Durnin and Womersley formula.15 The density value was then converted to percentage body fat using the Siri equation.16 The respondents body fat were classified separately for gender as too low, essential fat, athletes, fitness, acceptable, and obese as describe by American Council on Exercise.17 These 6 groups were then further clustered into health (essential fat, athletes, fitness) and unhealthy (too low, fitness, acceptable). BMI of each respondent was calculated using the formula; body weight in kilograms divide by height in metres squared (kg/m2). The respondents were categorised as healthy weight (18.5 to 23.9), overweight (24.0 to 26.9) and obese (27.0 and more) based on their BMI measurement.18 A cut-off point for waist circumference of more than 102cm in men and more than 88cm for women were used to define abdominal obesity and blood pressure was also measured.19 To analyze the effects of noxious particles to lung function, respondents were divided into two groups i.e. exposed and unexposed to noxious particles according to their occupation. Employment categorized as exposed to noxious particles included respondents who were working in the forestry, agricultural, elementary, or construction site categories. Not exposed included respondents who were professionals, students, housewives, unemployed or working in the tourism & services sector.

Ethics

An informed verbal consent was obtained from each respondent prior to participation in the study. An ethical approval was obtained from the ethics committee of the public health department of the institution prior to commencement of the study. The anonymity of the respondents is assured.

Analysis

Data was analyzed using SPSS version 20. Data is tabulated and descriptive statistics were expressed in frequency and percentage. Inferential statistics were done using independent sample t-test, ANOVA and Scheffe Post Hoc test was used to compare the significance of the difference between means of different groups within 95% confidence limit. Linear regression was used to identify the predictive variables. The level of significance was set at P<0.05.

Results

A total of 119 respondents out of the 161 eligible villagers participated in the study giving a response rate of 73.9%.
As shown in table 1 most of the participants were female (58.8%), in the age group 20-29 (42.0%), educated (84.0%), earning more than RM750 (40.5%) and were non smokers. A significant proportion were obese (37.3%) but with a normal waist hip ratio (71.4%) and a healthy body fat percentage (64.7%) and were normotensive (57.1%). The mean height and weight were 154.5cm and 62.4kg respectively. The predicted PEFR value for each individual was calculated using calculator incorporating age, height and gender.20 A total of 79 respondents (66.9%) reached 80% of their predicted PEFR value and 39 respondents (33.1%) fell below 80% of their predicted PEFR value.
As shown in table 2 the differences in the mean PEFR in gender (p=<0.001), level of education (p=<0.001), smoking status (p=<0.001) and body fat percentage (p=0.002) were statistically significant. The mean PEFR of those earning more than RM750 was higher than those earning RM251-500 (p=0.007).
A linear regression was conducted using gender, height, exposure to noxious particles and level of education as predictor variables. 62.0% (R2 0.62) of the variability in the PEFR score was explained by the variables in the model. Females had a lower mean PEFR as compared to males (p=<0.0001). Increase in height was associated with an increase in PEFR (p=0.004). Educated individuals (p=0.014) and those not exposed to noxious particles had better lung function (p= 0.023).

Discussion

PEFR is the maximum rate at which air is expelled from the lungs, measured in L/min. In people with obstructive airway disease, whether acute or chronic, measuring the PEFR provides an objective indication of the degrees of obstruction and predicted PEFR value is often used as a management plan.20,21 In the present study 66.9% of the respondents reached 80% of their predicted PEFR value. This finding contradicts the results of the Dugdale et al. study which showed the majority of the respondents had PEFR value below their predicted values.11 The difference found could be explained because of the altitude. People living in high altitudes have higher lung volumes23 due to the increase in lung diffusing capacity resulting in better lung function. The Semai tribe in this study is living in the hilly terrains of Cameron Highlands which requires physical exertion to track up the hills to their living quarters as compared to the aborigines from Dugdale et al. study who were mostly living on level terrains.
Most studies show that gender and height affect lung function with males and taller subjects having a higher PEFR.24,25 A study among adult Singaporean Chinese13 and another study among rural residents of Tamil Nadu, India26 also found similar results. This could be explained by the morphological differences in the lung structure between genders. It has been suggested that men have larger lung volumes, larger diameter airways, and larger diffusion surfaces compared to women.27 Women have smaller lung volume because they tend to have fewer total numbers of alveoli therefore a smaller surface area. Smaller lung volume accounts for smaller diameter airways in women and inevitably cause lower maximum flow rate.27,28 Another reason why there is a difference in PEFR between genders is because generally, males are taller compared to females. A study conducted among Kelantanese Malaysians24 found higher mean PEFR in both sexes compared to the respondents of the present study. This could be attributed to the difference in body height where the average heights of the participants of that study were taller to that of the present. In general the Orang Asli’s are shorter than the general Malaysian population.29 Another reason for the differences in gender could be because increase of estrogen levels in women tends to increase fluid retention and therefore increase blood volume which could potentially affect gas-exchange in the lung.30
People who are not exposed to noxious particles have better lung function with higher PEFR compared to those exposed to noxious particles because air pollution has a negative effect on an adults’ lung function.31 Inhalation of noxious particles causes abnormal inflammatory response which leads to airflow limitation.32,33 In the present study most of the participants who were exposed to noxious particles were uneducated or having lower levels of education and were employed as elementary workers. There is a close association of occupation and education. People who receive higher education are more likely to have a better working environment. Those working as elementary jobs were more likely to be exposed to dust, hazardous chemicals such as pesticides, insecticide aerosols which may contribute to decreased lung function.34,35 A study done in Boston in 1988 showed that PEFR was positively related to education.36 Furthermore, education may enable individuals to make better informed choices concerning food and lifestyles.37 It has been suggested that high intake of nutrients with antioxidant properties may reduce the rate of loss of lung function in adults.38-40

Conclusion

From this study, it can be concluded that height, gender, level of education and state of exposure to noxious particles have an effect on the PEFR among the Semai Orang Asli. Individual who are taller, male, with higher levels of education and not exposed to noxious particles have better lung function. It should be emphasized, however, that the amount of literature investigating these factors are limited especially among the Orang Asli. Therefore, more research is needed to further validate these findings.
There are a few limitations in this study. In general the Orang Asli population has lower life expectancy which resulted in the smaller sample of those aged 60 years and above. Most of the participants in this study were females because the breadwinner of the house which is usually the male was out working during the days when the study was undertaken.

Competing Interests

The authors declare that they have no competing interest.
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