Evaluation of Spirometric Values in Healthy Population Referred to Spirometry Centers in Hamedan City, Iran

Background: Spirometry procedure is known to be an efficient test for evaluating lung function. Nevertheless, the ventilatory function indexes acquired by spirometry seem to have been affected by several factors, some of which are demographic and anthropometric parameters. Hence, our study aimed to address the effect of some specific features of Hamedani individuals in Iran on spirometric characteristics. 
Methods: We assessed the spirometric parameters, including Forced Vital Capacity (FVC), forced expiratory volume in the first second (FEV1), maximal mid-expiratory flow rate (FEF25-75), and FEV1/FVC ratio, obtained from normal spirometry test of 1483 individuals between the ages of 16 and 89 years. 
Results: FVC, FEV1, FEV1/FVC ratio, and FEF25-75 were different between the two genders significantly (p<0.001). Even though there was a higher FVC, FEV1, and FEF25-75 in males, FEV1/FVC ratios for males were significantly lower than the ratios for females at the same ages (total mean of 82.09±6.78 in males versus 84.94±6.49 for females). In addition, FEV1/FVC ratio and FEF25-75 were not significantly different between tall males and females with a height of >170 cm. Finally, age and stature influenced the ventilatory function values with a correlation strength of <0.001. 
Conclusion: Albeit men, mostly because of their particular anatomic and physiologic feature of respiratory muscles, had larger FVC and FEV1, those who were tall showed no significant change in FEV1/FVC ratio and FEF25-75, in comparison with females. Irrespective of their height, men found a higher FEF25-75 as well.