Effect of age, gender, and body mass index on peak expiratory flow rate and other pulmonary function tests in healthy individuals in the age group 18-60 years

Background: Normal ageing and increasing body mass index (BMI) are related to decline in lung functions in adults in both genders. Females are more likely than age and height-matched males to show smaller lung size and diffusion surface, lower maximal expiratory flow rate, and reduced airway diameter. Lung mechanics and respiratory muscle strength, thoracic compliance, airway resistance, and elastic recoil of the lungs determine the pulmonary function tests (PFTs), and these tests are known to differ with age, sex, socio-economic status, cultural factors, and geographical region of the subject and are related to weight, height and BMI of the individuals. Aim and Objectives: The present study is planned to assess the peak expiratory flow rate (PEFR) and other PFTs and to evaluate the effect of age, gender and BMI on these lung functions. Materials and Methods: This study consists of 200 healthy individuals of age group 18–60 years. A sample was stratified into 5 age groups, and on the basis of BMI, the subjects were categorized as underweight, normal, overweight, and obese. Anthropometric measurements were recorded using standard procedures. PEFR was recorded using Wright’s peak-flow meter and forced vital capacity (FVC), Forced Expiratory Volume in 1 s (FEV1), FEV1/FVC, FEF25–75%, FEF2–1.2, slow vital capacity (SVC), and maximum voluntary ventilation (MVV) were analyzed using Expirograph (Helios 401, RMS, India). Chi-square test was used for analysis of categorical variables. For comparison of two groups, unpaired t-test was used and to assess the relation between the variables, Pearson’s co-relation was used. One way ANOVA was used to compare the difference between the means of more than two groups and Tukey post hoc analysis was done for multiple comparisons. Results: There was highly significant difference in the mean values of PEFR and other PFTs (P < 0.000) among the 5 age groups and a significant difference between younger and older age groups. PEFR, FVC, FEV1, FEV1/FVC, FEF25–75%, FEF0.2–1.2, SVC, and MVV were negatively correlated with age (r = −0.514, −0.535, −0.568, −0.255, −0.566, −0.516, −0.304, −0.523, respectively). Females showed reduced mean values of PEFR, FVC, FEV1, FEF25–75%, FEF0.2–1.2, SVC, MVV when compared to males (P < 0.000), and the differences in the mean values were significantly high. Highly significant difference was seen in the mean values of PEFR and other PFTs among the categories of BMI (P < 0.000). The mean values of FVC, FEV1, FEV1/FVC, FEF25–75%, FEF0.2–1.2, MVV were lower among underweight compared to their Access this article online Website: www.njppp. com Quick Response code DOI: 10.5455/njppp.2022. 12.08302202106102021 National Journal of Physiology, Pharmacy and Pharmacology Online 2022. © 2022 Komal Mankar, et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creative commons.org/licenses/by/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material for any purpose, even commercially, provided the original work is properly cited and states its license. National Journal of Physiology, Pharmacy and Pharmacology mean values among individuals with normal BMI. There was negative correlation between PEFR, FVC, FEV1, FEF25–75%, FEF0.2–1.2, SVC, MVV, and BMI (r = −0.327, −0.254, −0.238, −0.269, −0.254, −0.236, −0.195, respectively). Conclusions: PFTs aid in the prompt and accurate diagnosis of respiratory disorders, such as asthma, chronic obstructive pulmonary disease allowing for efficient management by encompassing a thorough Mankar et al. Pulmonary function tests in healthy individuals in the age group 18–60 years National Journal of Physiology, Pharmacy and Pharmacology 2 2022 | Vol 12 | Issue 04 (Online First) INTRODUCTION When God created human beings, he endowed them with energy, wisdom and intellect, brains for acquiring knowledge and various organs for doing work. In spite of the different functions of the cells in the body, they live in perfect harmony. As long as all the cells work in accordance with the principle of cooperation and unity, the entire body remains in a healthy condition. Many factors such as age, gender differences, obesity influence the functions of the cells of the human body. Life of a man is crucial between two breaths and parts that are large and in charge of breathing are the lungs. All the cells need oxygen to survive and expel carbon dioxide efficiently which is performed by lungs with its airways. Respiratory tract may be rightly regarded as the gateway for nutrition of the cells of the body. Thus, an efficient respiratory mechanics with patent airways is important in regulating the overall health and well-being. Various lifestyle disorders such as coronary heart disease, stroke, cancer, and chronic obstructive pulmonary disease (COPD) have become the major causes of death worldwide with increasing opulence and a rapidly ageing population. Respiratory insufficiency is associated with morbidity and mortality and ailing respiratory function predicts overall mortality besides death due to cancer, pulmonary disease, cardiovascular disease, and stroke. [1] Pulmonary function is known to differ with subject’s age, sex, race, ethnicity, socioeconomic status, cultural factors, and geographical region and is related to subject’s height, weight and body mass index (BMI) after adjusting for other factors such as age, race, gender, asthma, and smoking status in population that are at risk for impaired lung function. [2] Lung mechanics and respiratory muscle strength, thoracic compliance, airway resistance, and elastic recoil of the lungs determine the Pulmonary Function tests (PFTs). [3] Ageing affects the maintenance and restoration of homeostatic reserve of every organ negatively. With ageing, the respiratory system undergoes structural, physiological, and immunological changes. The lungs show decrease in static elastic recoil, respiratory muscle dysfunction and decrease in compliance of respiratory system, causing increased work of breathing with ageing. [4] Lung functions decline gradually after about the age of 35 and cross sectional analysis have showed that the decline may hasten after age 70. Obesity has become one of India’s major health burdens. In 2000, the World Health Organization (WHO) defined obesity as “abnormal or excessive fat accumulation in the body to the extent that the health and wellbeing are adversely affected. ” Weight and BMI indicate overall adiposity whereas waisthip ratio (WHR) and waist circumference (WC) measure the abdominal obesity. Overall adiposity is considered as predictor of pulmonary function whereas the abdominal obesity mechanically affects the lung compliance, effort of breathing and the elastic recoil[5] compared to general obesity, which may compress the chest wall, this may impede the fall of the diaphragm and limit lung expansion. The fact that total adiposity measurements do not discriminate between fat mass and muscle (lean) mass, which have opposing impacts on pulmonary function, is a fundamental flaw. [6] The BMI has long been used to categorize people as obese or non-obese. Obesity is defined as a BMI of 30 kg/m2 or more, according to the WHO and the International Obesity Task force. Unhealthy behaviors such as eating junk food, alcohol abuse, and sedentary lifestyle with mental stress are making one in every five Indian men and women either obese or overweight. The percentage of ever-married women aged 15–49 years who are overweight or obese grew from 11% in National Family Health Survey (NFHS)-2 to 15% in NFHS-3, according to the NFHS. Women have greater rates of undernutrition and overweight/obesity than males. This dual illness pattern in females may have an endocrine basis, but it is more likely due to societal and cultural norms which deprive them of a healthy lifestyle. Our country is dealing with a double whammy of underweight and overweight people. Approximately, 43–48% of Indian men and women between the ages of 15 and 45 are overweight or underweight, with 30–36% being underweight and 9–13% being overweight. [7] Undernourishment reduces the respiratory muscle mass curtailing the diaphragm contractility and other respiratory muscle performance. [8] Underweight subjects show reduced diaphragmatic mobility when compared to normal weight subjects. [9] Undernourishment is associated with poor respiratory muscle performance and severe airflow obstruction. PFTs are significant long-standing predictors of physical fitness in both genders and are essential to evaluate the individual’s respiratory system for diagnosis, treatment and rehabilitation of respiratory disorders. [10] Gender differences understanding of the disease and exercise respiratory training regimens even in otherwise healthy individuals. The present study showed that PEFR and other PFTs decrease with advancing age and BMI and females showed reduced lung functions compared to males.